Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

89 files changed, 21048 insertions, 0 deletions

diff --git a/gfx/layers/ipc/APZCTreeManagerChild.cpp b/gfx/layers/ipc/APZCTreeManagerChild.cpp
new file mode 100644
index 0000000000..b7f50c1c92
--- /dev/null
+++ b/gfx/layers/ipc/APZCTreeManagerChild.cpp
@@ -0,0 +1,230 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/APZCTreeManagerChild.h"
+
+#include "InputData.h"                              // for InputData
+#include "mozilla/dom/BrowserParent.h"              // for BrowserParent
+#include "mozilla/layers/APZCCallbackHelper.h"      // for APZCCallbackHelper
+#include "mozilla/layers/APZInputBridgeChild.h"     // for APZInputBridgeChild
+#include "mozilla/layers/GeckoContentController.h"  // for GeckoContentController
+#include "mozilla/layers/DoubleTapToZoom.h"  // for DoubleTapToZoomMetrics
+#include "mozilla/layers/RemoteCompositorSession.h"  // for RemoteCompositorSession
+#ifdef MOZ_WIDGET_ANDROID
+#  include "mozilla/jni/Utils.h"  // for DispatchToGeckoPriorityQueue
+#endif
+
+namespace mozilla {
+namespace layers {
+
+APZCTreeManagerChild::APZCTreeManagerChild()
+    : mCompositorSession(nullptr), mIPCOpen(false) {}
+
+APZCTreeManagerChild::~APZCTreeManagerChild() = default;
+
+void APZCTreeManagerChild::SetCompositorSession(
+    RemoteCompositorSession* aSession) {
+  // Exactly one of mCompositorSession and aSession must be null (i.e. either
+  // we're setting mCompositorSession or we're clearing it).
+  MOZ_ASSERT(!mCompositorSession ^ !aSession);
+  mCompositorSession = aSession;
+}
+
+void APZCTreeManagerChild::SetInputBridge(APZInputBridgeChild* aInputBridge) {
+  // The input bridge only exists from the UI process to the GPU process.
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(!mInputBridge);
+
+  mInputBridge = aInputBridge;
+}
+
+void APZCTreeManagerChild::Destroy() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mInputBridge) {
+    mInputBridge->Destroy();
+    mInputBridge = nullptr;
+  }
+}
+
+void APZCTreeManagerChild::SetKeyboardMap(const KeyboardMap& aKeyboardMap) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetKeyboardMap(aKeyboardMap);
+}
+
+void APZCTreeManagerChild::ZoomToRect(const ScrollableLayerGuid& aGuid,
+                                      const ZoomTarget& aZoomTarget,
+                                      const uint32_t aFlags) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendZoomToRect(aGuid, aZoomTarget, aFlags);
+}
+
+void APZCTreeManagerChild::ContentReceivedInputBlock(uint64_t aInputBlockId,
+                                                     bool aPreventDefault) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendContentReceivedInputBlock(aInputBlockId, aPreventDefault);
+}
+
+void APZCTreeManagerChild::SetTargetAPZC(
+    uint64_t aInputBlockId, const nsTArray<ScrollableLayerGuid>& aTargets) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetTargetAPZC(aInputBlockId, aTargets);
+}
+
+void APZCTreeManagerChild::UpdateZoomConstraints(
+    const ScrollableLayerGuid& aGuid,
+    const Maybe<ZoomConstraints>& aConstraints) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mIPCOpen) {
+    SendUpdateZoomConstraints(aGuid, aConstraints);
+  }
+}
+
+void APZCTreeManagerChild::SetDPI(float aDpiValue) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetDPI(aDpiValue);
+}
+
+void APZCTreeManagerChild::SetAllowedTouchBehavior(
+    uint64_t aInputBlockId, const nsTArray<TouchBehaviorFlags>& aValues) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetAllowedTouchBehavior(aInputBlockId, aValues);
+}
+
+void APZCTreeManagerChild::SetBrowserGestureResponse(
+    uint64_t aInputBlockId, BrowserGestureResponse aResponse) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetBrowserGestureResponse(aInputBlockId, aResponse);
+}
+
+void APZCTreeManagerChild::StartScrollbarDrag(
+    const ScrollableLayerGuid& aGuid, const AsyncDragMetrics& aDragMetrics) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendStartScrollbarDrag(aGuid, aDragMetrics);
+}
+
+bool APZCTreeManagerChild::StartAutoscroll(const ScrollableLayerGuid& aGuid,
+                                           const ScreenPoint& aAnchorLocation) {
+  MOZ_ASSERT(NS_IsMainThread());
+  return SendStartAutoscroll(aGuid, aAnchorLocation);
+}
+
+void APZCTreeManagerChild::StopAutoscroll(const ScrollableLayerGuid& aGuid) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendStopAutoscroll(aGuid);
+}
+
+void APZCTreeManagerChild::SetLongTapEnabled(bool aTapGestureEnabled) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SendSetLongTapEnabled(aTapGestureEnabled);
+}
+
+APZInputBridge* APZCTreeManagerChild::InputBridge() {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(mInputBridge);
+
+  return mInputBridge.get();
+}
+
+void APZCTreeManagerChild::AddIPDLReference() {
+  MOZ_ASSERT(mIPCOpen == false);
+  mIPCOpen = true;
+  AddRef();
+}
+
+void APZCTreeManagerChild::ReleaseIPDLReference() {
+  mIPCOpen = false;
+  Release();
+}
+
+void APZCTreeManagerChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mIPCOpen = false;
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerChild::RecvHandleTap(
+    const TapType& aType, const LayoutDevicePoint& aPoint,
+    const Modifiers& aModifiers, const ScrollableLayerGuid& aGuid,
+    const uint64_t& aInputBlockId,
+    const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  if (mCompositorSession &&
+      mCompositorSession->RootLayerTreeId() == aGuid.mLayersId &&
+      mCompositorSession->GetContentController()) {
+    RefPtr<GeckoContentController> controller =
+        mCompositorSession->GetContentController();
+    controller->HandleTap(aType, aPoint, aModifiers, aGuid, aInputBlockId,
+                          aDoubleTapToZoomMetrics);
+    return IPC_OK();
+  }
+  dom::BrowserParent* tab =
+      dom::BrowserParent::GetBrowserParentFromLayersId(aGuid.mLayersId);
+  if (tab) {
+#ifdef MOZ_WIDGET_ANDROID
+    // On Android, touch events are dispatched from the UI thread to the main
+    // thread using the Android priority queue. It is possible that this tap has
+    // made it to the GPU process and back before they have been processed. We
+    // must therefore dispatch this message to the same queue, otherwise the tab
+    // may receive the tap event before the touch events that synthesized it.
+    mozilla::jni::DispatchToGeckoPriorityQueue(
+        NewRunnableMethod<TapType, LayoutDevicePoint, Modifiers,
+                          ScrollableLayerGuid, uint64_t,
+                          Maybe<DoubleTapToZoomMetrics>>(
+            "dom::BrowserParent::SendHandleTap", tab,
+            &dom::BrowserParent::SendHandleTap, aType, aPoint, aModifiers,
+            aGuid, aInputBlockId, aDoubleTapToZoomMetrics));
+#else
+    tab->SendHandleTap(aType, aPoint, aModifiers, aGuid, aInputBlockId,
+                       aDoubleTapToZoomMetrics);
+#endif
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerChild::RecvNotifyPinchGesture(
+    const PinchGestureType& aType, const ScrollableLayerGuid& aGuid,
+    const LayoutDevicePoint& aFocusPoint, const LayoutDeviceCoord& aSpanChange,
+    const Modifiers& aModifiers) {
+  // This will only get sent from the GPU process to the parent process, so
+  // this function should never get called in the content process.
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // We want to handle it in this process regardless of what the target guid
+  // of the pinch is. This may change in the future.
+  if (mCompositorSession && mCompositorSession->GetWidget()) {
+    APZCCallbackHelper::NotifyPinchGesture(aType, aFocusPoint, aSpanChange,
+                                           aModifiers,
+                                           mCompositorSession->GetWidget());
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerChild::RecvCancelAutoscroll(
+    const ScrollableLayerGuid::ViewID& aScrollId) {
+  // This will only get sent from the GPU process to the parent process, so
+  // this function should never get called in the content process.
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  APZCCallbackHelper::CancelAutoscroll(aScrollId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerChild::RecvNotifyScaleGestureComplete(
+    const ScrollableLayerGuid::ViewID& aScrollId, float aScale) {
+  // This will only get sent from the GPU process to the parent process, so
+  // this function should never get called in the content process.
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (mCompositorSession && mCompositorSession->GetWidget()) {
+    APZCCallbackHelper::NotifyScaleGestureComplete(
+        mCompositorSession->GetWidget(), aScale);
+  }
+  return IPC_OK();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/APZCTreeManagerChild.h b/gfx/layers/ipc/APZCTreeManagerChild.h
new file mode 100644
index 0000000000..756677e1e3
--- /dev/null
+++ b/gfx/layers/ipc/APZCTreeManagerChild.h
@@ -0,0 +1,105 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_APZCTreeManagerChild_h
+#define mozilla_layers_APZCTreeManagerChild_h
+
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "mozilla/layers/PAPZCTreeManagerChild.h"
+
+#include <unordered_map>
+
+namespace mozilla {
+namespace layers {
+
+class APZInputBridgeChild;
+class RemoteCompositorSession;
+
+class APZCTreeManagerChild : public IAPZCTreeManager,
+                             public PAPZCTreeManagerChild {
+  friend class PAPZCTreeManagerChild;
+  using TapType = GeckoContentController_TapType;
+
+ public:
+  APZCTreeManagerChild();
+
+  void SetCompositorSession(RemoteCompositorSession* aSession);
+  void SetInputBridge(APZInputBridgeChild* aInputBridge);
+  void Destroy();
+
+  void SetKeyboardMap(const KeyboardMap& aKeyboardMap) override;
+
+  void ZoomToRect(const ScrollableLayerGuid& aGuid,
+                  const ZoomTarget& aZoomTarget,
+                  const uint32_t aFlags = DEFAULT_BEHAVIOR) override;
+
+  void ContentReceivedInputBlock(uint64_t aInputBlockId,
+                                 bool aPreventDefault) override;
+
+  void SetTargetAPZC(uint64_t aInputBlockId,
+                     const nsTArray<ScrollableLayerGuid>& aTargets) override;
+
+  void UpdateZoomConstraints(
+      const ScrollableLayerGuid& aGuid,
+      const Maybe<ZoomConstraints>& aConstraints) override;
+
+  void SetDPI(float aDpiValue) override;
+
+  void SetAllowedTouchBehavior(
+      uint64_t aInputBlockId,
+      const nsTArray<TouchBehaviorFlags>& aValues) override;
+
+  void SetBrowserGestureResponse(uint64_t aInputBlockId,
+                                 BrowserGestureResponse aResponse) override;
+
+  void StartScrollbarDrag(const ScrollableLayerGuid& aGuid,
+                          const AsyncDragMetrics& aDragMetrics) override;
+
+  bool StartAutoscroll(const ScrollableLayerGuid& aGuid,
+                       const ScreenPoint& aAnchorLocation) override;
+
+  void StopAutoscroll(const ScrollableLayerGuid& aGuid) override;
+
+  void SetLongTapEnabled(bool aTapGestureEnabled) override;
+
+  APZInputBridge* InputBridge() override;
+
+  void AddIPDLReference();
+  void ReleaseIPDLReference();
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+ protected:
+  MOZ_CAN_RUN_SCRIPT_BOUNDARY
+  mozilla::ipc::IPCResult RecvHandleTap(
+      const TapType& aType, const LayoutDevicePoint& aPoint,
+      const Modifiers& aModifiers, const ScrollableLayerGuid& aGuid,
+      const uint64_t& aInputBlockId,
+      const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics);
+
+  mozilla::ipc::IPCResult RecvNotifyPinchGesture(
+      const PinchGestureType& aType, const ScrollableLayerGuid& aGuid,
+      const LayoutDevicePoint& aFocusPoint,
+      const LayoutDeviceCoord& aSpanChange, const Modifiers& aModifiers);
+
+  mozilla::ipc::IPCResult RecvCancelAutoscroll(
+      const ScrollableLayerGuid::ViewID& aScrollId);
+
+  mozilla::ipc::IPCResult RecvNotifyScaleGestureComplete(
+      const ScrollableLayerGuid::ViewID& aScrollId, float aScale);
+
+  virtual ~APZCTreeManagerChild();
+
+ private:
+  MOZ_NON_OWNING_REF RemoteCompositorSession* mCompositorSession;
+  RefPtr<APZInputBridgeChild> mInputBridge;
+  bool mIPCOpen;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_APZCTreeManagerChild_h
diff --git a/gfx/layers/ipc/APZCTreeManagerParent.cpp b/gfx/layers/ipc/APZCTreeManagerParent.cpp
new file mode 100644
index 0000000000..ff05acd083
--- /dev/null
+++ b/gfx/layers/ipc/APZCTreeManagerParent.cpp
@@ -0,0 +1,199 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/APZCTreeManagerParent.h"
+
+#include "apz/src/APZCTreeManager.h"
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/layers/APZUpdater.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace layers {
+
+APZCTreeManagerParent::APZCTreeManagerParent(
+    LayersId aLayersId, RefPtr<APZCTreeManager> aAPZCTreeManager,
+    RefPtr<APZUpdater> aAPZUpdater)
+    : mLayersId(aLayersId),
+      mTreeManager(std::move(aAPZCTreeManager)),
+      mUpdater(std::move(aAPZUpdater)) {
+  MOZ_ASSERT(mTreeManager != nullptr);
+  MOZ_ASSERT(mUpdater != nullptr);
+  MOZ_ASSERT(mUpdater->HasTreeManager(mTreeManager));
+}
+
+APZCTreeManagerParent::~APZCTreeManagerParent() = default;
+
+void APZCTreeManagerParent::ChildAdopted(
+    RefPtr<APZCTreeManager> aAPZCTreeManager, RefPtr<APZUpdater> aAPZUpdater) {
+  MOZ_ASSERT(aAPZCTreeManager != nullptr);
+  MOZ_ASSERT(aAPZUpdater != nullptr);
+  MOZ_ASSERT(aAPZUpdater->HasTreeManager(aAPZCTreeManager));
+  mTreeManager = std::move(aAPZCTreeManager);
+  mUpdater = std::move(aAPZUpdater);
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetKeyboardMap(
+    const KeyboardMap& aKeyboardMap) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId, NewRunnableMethod<KeyboardMap>(
+                     "layers::IAPZCTreeManager::SetKeyboardMap", mTreeManager,
+                     &IAPZCTreeManager::SetKeyboardMap, aKeyboardMap));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvZoomToRect(
+    const ScrollableLayerGuid& aGuid, const ZoomTarget& aZoomTarget,
+    const uint32_t& aFlags) {
+  if (!IsGuidValid(aGuid)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  mUpdater->RunOnUpdaterThread(
+      aGuid.mLayersId,
+      NewRunnableMethod<ScrollableLayerGuid, ZoomTarget, uint32_t>(
+          "layers::IAPZCTreeManager::ZoomToRect", mTreeManager,
+          &IAPZCTreeManager::ZoomToRect, aGuid, aZoomTarget, aFlags));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvContentReceivedInputBlock(
+    const uint64_t& aInputBlockId, const bool& aPreventDefault) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId, NewRunnableMethod<uint64_t, bool>(
+                     "layers::IAPZCTreeManager::ContentReceivedInputBlock",
+                     mTreeManager, &IAPZCTreeManager::ContentReceivedInputBlock,
+                     aInputBlockId, aPreventDefault));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetTargetAPZC(
+    const uint64_t& aInputBlockId, nsTArray<ScrollableLayerGuid>&& aTargets) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId,
+      NewRunnableMethod<uint64_t,
+                        StoreCopyPassByRRef<nsTArray<ScrollableLayerGuid>>>(
+          "layers::IAPZCTreeManager::SetTargetAPZC", mTreeManager,
+          &IAPZCTreeManager::SetTargetAPZC, aInputBlockId,
+          std::move(aTargets)));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvUpdateZoomConstraints(
+    const ScrollableLayerGuid& aGuid,
+    const Maybe<ZoomConstraints>& aConstraints) {
+  if (!IsGuidValid(aGuid)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  mTreeManager->UpdateZoomConstraints(aGuid, aConstraints);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetDPI(
+    const float& aDpiValue) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId,
+      NewRunnableMethod<float>("layers::IAPZCTreeManager::SetDPI", mTreeManager,
+                               &IAPZCTreeManager::SetDPI, aDpiValue));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetAllowedTouchBehavior(
+    const uint64_t& aInputBlockId, nsTArray<TouchBehaviorFlags>&& aValues) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId,
+      NewRunnableMethod<uint64_t,
+                        StoreCopyPassByRRef<nsTArray<TouchBehaviorFlags>>>(
+          "layers::IAPZCTreeManager::SetAllowedTouchBehavior", mTreeManager,
+          &IAPZCTreeManager::SetAllowedTouchBehavior, aInputBlockId,
+          std::move(aValues)));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetBrowserGestureResponse(
+    const uint64_t& aInputBlockId, const BrowserGestureResponse& aResponse) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId, NewRunnableMethod<uint64_t, BrowserGestureResponse>(
+                     "layers::IAPZCTreeManager::SetBrowserGestureResponse",
+                     mTreeManager, &IAPZCTreeManager::SetBrowserGestureResponse,
+                     aInputBlockId, aResponse));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvStartScrollbarDrag(
+    const ScrollableLayerGuid& aGuid, const AsyncDragMetrics& aDragMetrics) {
+  if (!IsGuidValid(aGuid)) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  mUpdater->RunOnUpdaterThread(
+      aGuid.mLayersId,
+      NewRunnableMethod<ScrollableLayerGuid, AsyncDragMetrics>(
+          "layers::IAPZCTreeManager::StartScrollbarDrag", mTreeManager,
+          &IAPZCTreeManager::StartScrollbarDrag, aGuid, aDragMetrics));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvStartAutoscroll(
+    const ScrollableLayerGuid& aGuid, const ScreenPoint& aAnchorLocation) {
+  // Unlike RecvStartScrollbarDrag(), this message comes from the parent
+  // process (via nsBaseWidget::mAPZC) rather than from the child process
+  // (via BrowserChild::mApzcTreeManager), so there is no need to check the
+  // layers id against mLayersId (and in any case, it wouldn't match, because
+  // mLayersId stores the parent process's layers id, while nsBaseWidget is
+  // sending the child process's layers id).
+
+  mUpdater->RunOnControllerThread(
+      mLayersId,
+      NewRunnableMethod<ScrollableLayerGuid, ScreenPoint>(
+          "layers::IAPZCTreeManager::StartAutoscroll", mTreeManager,
+          &IAPZCTreeManager::StartAutoscroll, aGuid, aAnchorLocation));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvStopAutoscroll(
+    const ScrollableLayerGuid& aGuid) {
+  // See RecvStartAutoscroll() for why we don't check the layers id.
+
+  mUpdater->RunOnControllerThread(
+      mLayersId, NewRunnableMethod<ScrollableLayerGuid>(
+                     "layers::IAPZCTreeManager::StopAutoscroll", mTreeManager,
+                     &IAPZCTreeManager::StopAutoscroll, aGuid));
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZCTreeManagerParent::RecvSetLongTapEnabled(
+    const bool& aLongTapEnabled) {
+  mUpdater->RunOnUpdaterThread(
+      mLayersId,
+      NewRunnableMethod<bool>(
+          "layers::IAPZCTreeManager::SetLongTapEnabled", mTreeManager,
+          &IAPZCTreeManager::SetLongTapEnabled, aLongTapEnabled));
+
+  return IPC_OK();
+}
+
+bool APZCTreeManagerParent::IsGuidValid(const ScrollableLayerGuid& aGuid) {
+  if (aGuid.mLayersId != mLayersId) {
+    NS_ERROR("Unexpected layers id");
+    return false;
+  }
+  return true;
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/APZCTreeManagerParent.h b/gfx/layers/ipc/APZCTreeManagerParent.h
new file mode 100644
index 0000000000..c75091c796
--- /dev/null
+++ b/gfx/layers/ipc/APZCTreeManagerParent.h
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_APZCTreeManagerParent_h
+#define mozilla_layers_APZCTreeManagerParent_h
+
+#include "mozilla/layers/PAPZCTreeManagerParent.h"
+
+namespace mozilla {
+namespace layers {
+
+class APZCTreeManager;
+class APZUpdater;
+
+class APZCTreeManagerParent : public PAPZCTreeManagerParent {
+ public:
+  APZCTreeManagerParent(LayersId aLayersId,
+                        RefPtr<APZCTreeManager> aAPZCTreeManager,
+                        RefPtr<APZUpdater> mAPZUpdater);
+  virtual ~APZCTreeManagerParent();
+
+  LayersId GetLayersId() const { return mLayersId; }
+
+  /**
+   * Called when the layer tree that this protocol is connected to
+   * is adopted by another compositor, and we need to switch APZCTreeManagers.
+   */
+  void ChildAdopted(RefPtr<APZCTreeManager> aAPZCTreeManager,
+                    RefPtr<APZUpdater> aAPZUpdater);
+
+  mozilla::ipc::IPCResult RecvSetKeyboardMap(const KeyboardMap& aKeyboardMap);
+
+  mozilla::ipc::IPCResult RecvZoomToRect(const ScrollableLayerGuid& aGuid,
+                                         const ZoomTarget& aZoomTarget,
+                                         const uint32_t& aFlags);
+
+  mozilla::ipc::IPCResult RecvContentReceivedInputBlock(
+      const uint64_t& aInputBlockId, const bool& aPreventDefault);
+
+  mozilla::ipc::IPCResult RecvSetTargetAPZC(
+      const uint64_t& aInputBlockId, nsTArray<ScrollableLayerGuid>&& aTargets);
+
+  mozilla::ipc::IPCResult RecvUpdateZoomConstraints(
+      const ScrollableLayerGuid& aGuid,
+      const Maybe<ZoomConstraints>& aConstraints);
+
+  mozilla::ipc::IPCResult RecvSetDPI(const float& aDpiValue);
+
+  mozilla::ipc::IPCResult RecvSetAllowedTouchBehavior(
+      const uint64_t& aInputBlockId, nsTArray<TouchBehaviorFlags>&& aValues);
+
+  mozilla::ipc::IPCResult RecvSetBrowserGestureResponse(
+      const uint64_t& aInputBlockId, const BrowserGestureResponse& aResponse);
+
+  mozilla::ipc::IPCResult RecvStartScrollbarDrag(
+      const ScrollableLayerGuid& aGuid, const AsyncDragMetrics& aDragMetrics);
+
+  mozilla::ipc::IPCResult RecvStartAutoscroll(
+      const ScrollableLayerGuid& aGuid, const ScreenPoint& aAnchorLocation);
+
+  mozilla::ipc::IPCResult RecvStopAutoscroll(const ScrollableLayerGuid& aGuid);
+
+  mozilla::ipc::IPCResult RecvSetLongTapEnabled(const bool& aTapGestureEnabled);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override {}
+
+ private:
+  bool IsGuidValid(const ScrollableLayerGuid& aGuid);
+
+  LayersId mLayersId;
+  RefPtr<APZCTreeManager> mTreeManager;
+  RefPtr<APZUpdater> mUpdater;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_APZCTreeManagerParent_h
diff --git a/gfx/layers/ipc/APZChild.cpp b/gfx/layers/ipc/APZChild.cpp
new file mode 100644
index 0000000000..00146ac59a
--- /dev/null
+++ b/gfx/layers/ipc/APZChild.cpp
@@ -0,0 +1,113 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/APZChild.h"
+#include "mozilla/layers/GeckoContentController.h"
+
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/layers/APZCCallbackHelper.h"
+
+#include "InputData.h"  // for InputData
+
+namespace mozilla {
+namespace layers {
+
+APZChild::APZChild(RefPtr<GeckoContentController> aController)
+    : mController(aController) {
+  MOZ_ASSERT(mController);
+}
+
+APZChild::~APZChild() {
+  if (mAPZTaskRunnable) {
+    mAPZTaskRunnable->Revoke();
+    mAPZTaskRunnable = nullptr;
+  }
+  if (mController) {
+    mController->Destroy();
+    mController = nullptr;
+  }
+}
+
+mozilla::ipc::IPCResult APZChild::RecvLayerTransforms(
+    nsTArray<MatrixMessage>&& aTransforms) {
+  mController->NotifyLayerTransforms(std::move(aTransforms));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvRequestContentRepaint(
+    const RepaintRequest& aRequest) {
+  MOZ_ASSERT(mController->IsRepaintThread());
+
+  EnsureAPZTaskRunnable();
+
+  mAPZTaskRunnable->QueueRequest(aRequest);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvUpdateOverscrollVelocity(
+    const ScrollableLayerGuid& aGuid, const float& aX, const float& aY,
+    const bool& aIsRootContent) {
+  mController->UpdateOverscrollVelocity(aGuid, aX, aY, aIsRootContent);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvUpdateOverscrollOffset(
+    const ScrollableLayerGuid& aGuid, const float& aX, const float& aY,
+    const bool& aIsRootContent) {
+  mController->UpdateOverscrollOffset(aGuid, aX, aY, aIsRootContent);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyMozMouseScrollEvent(
+    const ViewID& aScrollId, const nsString& aEvent) {
+  mController->NotifyMozMouseScrollEvent(aScrollId, aEvent);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyAPZStateChange(
+    const ScrollableLayerGuid& aGuid, const APZStateChange& aChange,
+    const int& aArg, Maybe<uint64_t> aInputBlockId) {
+  mController->NotifyAPZStateChange(aGuid, aChange, aArg, aInputBlockId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyFlushComplete() {
+  MOZ_ASSERT(mController->IsRepaintThread());
+  EnsureAPZTaskRunnable();
+
+  mAPZTaskRunnable->QueueFlushCompleteNotification();
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyAsyncScrollbarDragInitiated(
+    const uint64_t& aDragBlockId, const ViewID& aScrollId,
+    const ScrollDirection& aDirection) {
+  mController->NotifyAsyncScrollbarDragInitiated(aDragBlockId, aScrollId,
+                                                 aDirection);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyAsyncScrollbarDragRejected(
+    const ViewID& aScrollId) {
+  mController->NotifyAsyncScrollbarDragRejected(aScrollId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvNotifyAsyncAutoscrollRejected(
+    const ViewID& aScrollId) {
+  mController->NotifyAsyncAutoscrollRejected(aScrollId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZChild::RecvDestroy() {
+  // mController->Destroy will be called in the destructor
+  PAPZChild::Send__delete__(this);
+  return IPC_OK();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/APZChild.h b/gfx/layers/ipc/APZChild.h
new file mode 100644
index 0000000000..dfb3216127
--- /dev/null
+++ b/gfx/layers/ipc/APZChild.h
@@ -0,0 +1,79 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_APZChild_h
+#define mozilla_layers_APZChild_h
+
+#include "mozilla/layers/PAPZChild.h"
+#include "mozilla/layers/APZTaskRunnable.h"
+
+namespace mozilla {
+namespace layers {
+
+class GeckoContentController;
+
+/**
+ * APZChild implements PAPZChild and is used to remote a GeckoContentController
+ * that lives in a different process than where APZ lives.
+ */
+class APZChild final : public PAPZChild {
+ public:
+  using APZStateChange = GeckoContentController_APZStateChange;
+
+  explicit APZChild(RefPtr<GeckoContentController> aController);
+  virtual ~APZChild();
+
+  mozilla::ipc::IPCResult RecvLayerTransforms(
+      nsTArray<MatrixMessage>&& aTransforms);
+
+  mozilla::ipc::IPCResult RecvRequestContentRepaint(
+      const RepaintRequest& aRequest);
+
+  mozilla::ipc::IPCResult RecvUpdateOverscrollVelocity(
+      const ScrollableLayerGuid& aGuid, const float& aX, const float& aY,
+      const bool& aIsRootContent);
+
+  mozilla::ipc::IPCResult RecvUpdateOverscrollOffset(
+      const ScrollableLayerGuid& aGuid, const float& aX, const float& aY,
+      const bool& aIsRootContent);
+
+  mozilla::ipc::IPCResult RecvNotifyMozMouseScrollEvent(const ViewID& aScrollId,
+                                                        const nsString& aEvent);
+
+  mozilla::ipc::IPCResult RecvNotifyAPZStateChange(
+      const ScrollableLayerGuid& aGuid, const APZStateChange& aChange,
+      const int& aArg, Maybe<uint64_t> aInputBlockId);
+
+  mozilla::ipc::IPCResult RecvNotifyFlushComplete();
+
+  mozilla::ipc::IPCResult RecvNotifyAsyncScrollbarDragInitiated(
+      const uint64_t& aDragBlockId, const ViewID& aScrollId,
+      const ScrollDirection& aDirection);
+  mozilla::ipc::IPCResult RecvNotifyAsyncScrollbarDragRejected(
+      const ViewID& aScrollId);
+
+  mozilla::ipc::IPCResult RecvNotifyAsyncAutoscrollRejected(
+      const ViewID& aScrollId);
+
+  mozilla::ipc::IPCResult RecvDestroy();
+
+ private:
+  void EnsureAPZTaskRunnable() {
+    if (!mAPZTaskRunnable) {
+      mAPZTaskRunnable = new APZTaskRunnable(mController);
+    }
+  }
+
+  RefPtr<GeckoContentController> mController;
+  // A runnable invoked in a nsRefreshDriver's tick to update multiple
+  // RepaintRequests and notify a "apz-repaints-flushed" at the same time.
+  RefPtr<APZTaskRunnable> mAPZTaskRunnable;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_APZChild_h
diff --git a/gfx/layers/ipc/APZInputBridgeChild.cpp b/gfx/layers/ipc/APZInputBridgeChild.cpp
new file mode 100644
index 0000000000..bf059143ec
--- /dev/null
+++ b/gfx/layers/ipc/APZInputBridgeChild.cpp
@@ -0,0 +1,211 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/APZInputBridgeChild.h"
+
+#include "InputData.h"  // for InputData, etc
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/layers/SynchronousTask.h"
+
+namespace mozilla {
+namespace layers {
+
+/* static */
+RefPtr<APZInputBridgeChild> APZInputBridgeChild::Create(
+    const uint64_t& aProcessToken, Endpoint<PAPZInputBridgeChild>&& aEndpoint) {
+  RefPtr<APZInputBridgeChild> child = new APZInputBridgeChild(aProcessToken);
+
+  MOZ_ASSERT(APZThreadUtils::IsControllerThreadAlive());
+
+  APZThreadUtils::RunOnControllerThread(
+      NewRunnableMethod<Endpoint<PAPZInputBridgeChild>&&>(
+          "layers::APZInputBridgeChild::Open", child,
+          &APZInputBridgeChild::Open, std::move(aEndpoint)));
+
+  return child;
+}
+
+APZInputBridgeChild::APZInputBridgeChild(const uint64_t& aProcessToken)
+    : mIsOpen(false), mProcessToken(aProcessToken) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+APZInputBridgeChild::~APZInputBridgeChild() = default;
+
+void APZInputBridgeChild::Open(Endpoint<PAPZInputBridgeChild>&& aEndpoint) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  mIsOpen = aEndpoint.Bind(this);
+
+  if (!mIsOpen) {
+    // The GPU Process Manager might be gone if we receive ActorDestroy very
+    // late in shutdown.
+    if (gfx::GPUProcessManager* gpm = gfx::GPUProcessManager::Get()) {
+      gpm->NotifyRemoteActorDestroyed(mProcessToken);
+    }
+    return;
+  }
+}
+
+void APZInputBridgeChild::Destroy() {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Destroy will get called from the main thread, so we must synchronously
+  // dispatch to the controller thread to close the bridge.
+  layers::SynchronousTask task("layers::APZInputBridgeChild::Destroy");
+  APZThreadUtils::RunOnControllerThread(
+      NS_NewRunnableFunction("layers::APZInputBridgeChild::Destroy", [&]() {
+        APZThreadUtils::AssertOnControllerThread();
+        AutoCompleteTask complete(&task);
+
+        // Clear the process token so that we don't notify the GPUProcessManager
+        // about an abnormal shutdown, thereby tearing down the GPU process.
+        mProcessToken = 0;
+
+        if (mIsOpen) {
+          PAPZInputBridgeChild::Close();
+          mIsOpen = false;
+        }
+      }));
+
+  task.Wait();
+}
+
+void APZInputBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mIsOpen = false;
+
+  if (mProcessToken) {
+    gfx::GPUProcessManager::Get()->NotifyRemoteActorDestroyed(mProcessToken);
+    mProcessToken = 0;
+  }
+}
+
+APZEventResult APZInputBridgeChild::ReceiveInputEvent(
+    InputData& aEvent, InputBlockCallback&& aCallback) {
+  MOZ_ASSERT(mIsOpen);
+  APZThreadUtils::AssertOnControllerThread();
+
+  APZEventResult res;
+  switch (aEvent.mInputType) {
+    case MULTITOUCH_INPUT: {
+      MultiTouchInput& event = aEvent.AsMultiTouchInput();
+      MultiTouchInput processedEvent;
+
+      SendReceiveMultiTouchInputEvent(event, !!aCallback, &res,
+                                      &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case MOUSE_INPUT: {
+      MouseInput& event = aEvent.AsMouseInput();
+      MouseInput processedEvent;
+
+      SendReceiveMouseInputEvent(event, !!aCallback, &res, &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case PANGESTURE_INPUT: {
+      PanGestureInput& event = aEvent.AsPanGestureInput();
+      PanGestureInput processedEvent;
+
+      SendReceivePanGestureInputEvent(event, !!aCallback, &res,
+                                      &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case PINCHGESTURE_INPUT: {
+      PinchGestureInput& event = aEvent.AsPinchGestureInput();
+      PinchGestureInput processedEvent;
+
+      SendReceivePinchGestureInputEvent(event, !!aCallback, &res,
+                                        &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case TAPGESTURE_INPUT: {
+      TapGestureInput& event = aEvent.AsTapGestureInput();
+      TapGestureInput processedEvent;
+
+      SendReceiveTapGestureInputEvent(event, !!aCallback, &res,
+                                      &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case SCROLLWHEEL_INPUT: {
+      ScrollWheelInput& event = aEvent.AsScrollWheelInput();
+      ScrollWheelInput processedEvent;
+
+      SendReceiveScrollWheelInputEvent(event, !!aCallback, &res,
+                                       &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    case KEYBOARD_INPUT: {
+      KeyboardInput& event = aEvent.AsKeyboardInput();
+      KeyboardInput processedEvent;
+
+      SendReceiveKeyboardInputEvent(event, !!aCallback, &res, &processedEvent);
+
+      event = processedEvent;
+      break;
+    }
+    default: {
+      MOZ_ASSERT_UNREACHABLE("Invalid InputData type.");
+      res.SetStatusAsConsumeNoDefault();
+      break;
+    }
+  }
+
+  if (aCallback && res.WillHaveDelayedResult()) {
+    mInputBlockCallbacks.emplace(res.mInputBlockId, std::move(aCallback));
+  }
+
+  return res;
+}
+
+mozilla::ipc::IPCResult APZInputBridgeChild::RecvCallInputBlockCallback(
+    uint64_t aInputBlockId, const APZHandledResult& aHandledResult) {
+  auto it = mInputBlockCallbacks.find(aInputBlockId);
+  if (it != mInputBlockCallbacks.end()) {
+    it->second(aInputBlockId, aHandledResult);
+    // The callback is one-shot; discard it after calling it.
+    mInputBlockCallbacks.erase(it);
+  }
+
+  return IPC_OK();
+}
+
+void APZInputBridgeChild::ProcessUnhandledEvent(
+    LayoutDeviceIntPoint* aRefPoint, ScrollableLayerGuid* aOutTargetGuid,
+    uint64_t* aOutFocusSequenceNumber, LayersId* aOutLayersId) {
+  MOZ_ASSERT(mIsOpen);
+  APZThreadUtils::AssertOnControllerThread();
+
+  SendProcessUnhandledEvent(*aRefPoint, aRefPoint, aOutTargetGuid,
+                            aOutFocusSequenceNumber, aOutLayersId);
+}
+
+void APZInputBridgeChild::UpdateWheelTransaction(
+    LayoutDeviceIntPoint aRefPoint, EventMessage aEventMessage,
+    const Maybe<ScrollableLayerGuid>& aTargetGuid) {
+  MOZ_ASSERT(mIsOpen);
+  APZThreadUtils::AssertOnControllerThread();
+
+  SendUpdateWheelTransaction(aRefPoint, aEventMessage, aTargetGuid);
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/APZInputBridgeChild.h b/gfx/layers/ipc/APZInputBridgeChild.h
new file mode 100644
index 0000000000..dd77d95f36
--- /dev/null
+++ b/gfx/layers/ipc/APZInputBridgeChild.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_APZInputBridgeChild_h
+#define mozilla_layers_APZInputBridgeChild_h
+
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/PAPZInputBridgeChild.h"
+
+namespace mozilla {
+namespace layers {
+
+class APZInputBridgeChild : public PAPZInputBridgeChild, public APZInputBridge {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(APZInputBridgeChild, final)
+
+ public:
+  static RefPtr<APZInputBridgeChild> Create(
+      const uint64_t& aProcessToken,
+      Endpoint<PAPZInputBridgeChild>&& aEndpoint);
+
+  void Destroy();
+
+  APZEventResult ReceiveInputEvent(
+      InputData& aEvent,
+      InputBlockCallback&& aCallback = InputBlockCallback()) override;
+
+  mozilla::ipc::IPCResult RecvCallInputBlockCallback(
+      uint64_t aInputBlockId, const APZHandledResult& handledResult);
+
+ protected:
+  void ProcessUnhandledEvent(LayoutDeviceIntPoint* aRefPoint,
+                             ScrollableLayerGuid* aOutTargetGuid,
+                             uint64_t* aOutFocusSequenceNumber,
+                             LayersId* aOutLayersId) override;
+
+  void UpdateWheelTransaction(
+      LayoutDeviceIntPoint aRefPoint, EventMessage aEventMessage,
+      const Maybe<ScrollableLayerGuid>& aTargetGuid) override;
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  explicit APZInputBridgeChild(const uint64_t& aProcessToken);
+  virtual ~APZInputBridgeChild();
+
+ private:
+  void Open(Endpoint<PAPZInputBridgeChild>&& aEndpoint);
+
+  bool mIsOpen;
+  uint64_t mProcessToken;
+
+  using InputBlockCallbackMap =
+      std::unordered_map<uint64_t, InputBlockCallback>;
+  InputBlockCallbackMap mInputBlockCallbacks;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_APZInputBridgeChild_h
diff --git a/gfx/layers/ipc/APZInputBridgeParent.cpp b/gfx/layers/ipc/APZInputBridgeParent.cpp
new file mode 100644
index 0000000000..fcc642ff7a
--- /dev/null
+++ b/gfx/layers/ipc/APZInputBridgeParent.cpp
@@ -0,0 +1,213 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/APZInputBridgeParent.h"
+
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "InputData.h"
+
+namespace mozilla {
+namespace layers {
+
+/* static */
+RefPtr<APZInputBridgeParent> APZInputBridgeParent::Create(
+    const LayersId& aLayersId, Endpoint<PAPZInputBridgeParent>&& aEndpoint) {
+  RefPtr<APZInputBridgeParent> parent = new APZInputBridgeParent(aLayersId);
+  if (!aEndpoint.Bind(parent)) {
+    // We can't recover from this.
+    MOZ_CRASH("Failed to bind APZInputBridgeParent to endpoint");
+  }
+
+  return parent;
+}
+
+APZInputBridgeParent::APZInputBridgeParent(const LayersId& aLayersId) {
+  MOZ_ASSERT(XRE_IsGPUProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mTreeManager = CompositorBridgeParent::GetAPZCTreeManager(aLayersId);
+  MOZ_ASSERT(mTreeManager);
+}
+
+APZInputBridgeParent::~APZInputBridgeParent() = default;
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceiveMultiTouchInputEvent(
+    const MultiTouchInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, MultiTouchInput* aOutEvent) {
+  MultiTouchInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceiveMouseInputEvent(
+    const MouseInput& aEvent, bool aWantsCallback, APZEventResult* aOutResult,
+    MouseInput* aOutEvent) {
+  MouseInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceivePanGestureInputEvent(
+    const PanGestureInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, PanGestureInput* aOutEvent) {
+  PanGestureInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceivePinchGestureInputEvent(
+    const PinchGestureInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, PinchGestureInput* aOutEvent) {
+  PinchGestureInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceiveTapGestureInputEvent(
+    const TapGestureInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, TapGestureInput* aOutEvent) {
+  TapGestureInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceiveScrollWheelInputEvent(
+    const ScrollWheelInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, ScrollWheelInput* aOutEvent) {
+  ScrollWheelInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvReceiveKeyboardInputEvent(
+    const KeyboardInput& aEvent, bool aWantsCallback,
+    APZEventResult* aOutResult, KeyboardInput* aOutEvent) {
+  KeyboardInput event = aEvent;
+
+  APZInputBridge::InputBlockCallback callback;
+  if (aWantsCallback) {
+    callback = [self = RefPtr<APZInputBridgeParent>(this)](
+                   uint64_t aInputBlockId,
+                   const APZHandledResult& aHandledResult) {
+      Unused << self->SendCallInputBlockCallback(aInputBlockId, aHandledResult);
+    };
+  }
+
+  *aOutResult = mTreeManager->InputBridge()->ReceiveInputEvent(
+      event, std::move(callback));
+  *aOutEvent = event;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvUpdateWheelTransaction(
+    const LayoutDeviceIntPoint& aRefPoint, const EventMessage& aEventMessage,
+    const Maybe<ScrollableLayerGuid>& aTargetGuid) {
+  mTreeManager->InputBridge()->UpdateWheelTransaction(aRefPoint, aEventMessage,
+                                                      aTargetGuid);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult APZInputBridgeParent::RecvProcessUnhandledEvent(
+    const LayoutDeviceIntPoint& aRefPoint, LayoutDeviceIntPoint* aOutRefPoint,
+    ScrollableLayerGuid* aOutTargetGuid, uint64_t* aOutFocusSequenceNumber,
+    LayersId* aOutLayersId) {
+  LayoutDeviceIntPoint refPoint = aRefPoint;
+  mTreeManager->InputBridge()->ProcessUnhandledEvent(
+      &refPoint, aOutTargetGuid, aOutFocusSequenceNumber, aOutLayersId);
+  *aOutRefPoint = refPoint;
+
+  return IPC_OK();
+}
+
+void APZInputBridgeParent::ActorDestroy(ActorDestroyReason aWhy) {
+  // We shouldn't need it after this
+  mTreeManager = nullptr;
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/APZInputBridgeParent.h b/gfx/layers/ipc/APZInputBridgeParent.h
new file mode 100644
index 0000000000..71f43d092b
--- /dev/null
+++ b/gfx/layers/ipc/APZInputBridgeParent.h
@@ -0,0 +1,75 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_APZInputBridgeParent_h
+#define mozilla_layers_APZInputBridgeParent_h
+
+#include "mozilla/layers/PAPZInputBridgeParent.h"
+
+namespace mozilla {
+namespace layers {
+
+class IAPZCTreeManager;
+
+class APZInputBridgeParent : public PAPZInputBridgeParent {
+  NS_INLINE_DECL_REFCOUNTING(APZInputBridgeParent, final)
+
+ public:
+  static RefPtr<APZInputBridgeParent> Create(
+      const LayersId& aLayersId, Endpoint<PAPZInputBridgeParent>&& aEndpoint);
+
+  mozilla::ipc::IPCResult RecvReceiveMultiTouchInputEvent(
+      const MultiTouchInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, MultiTouchInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceiveMouseInputEvent(const MouseInput& aEvent,
+                                                     bool aWantsCallback,
+                                                     APZEventResult* aOutResult,
+                                                     MouseInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceivePanGestureInputEvent(
+      const PanGestureInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, PanGestureInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceivePinchGestureInputEvent(
+      const PinchGestureInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, PinchGestureInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceiveTapGestureInputEvent(
+      const TapGestureInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, TapGestureInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceiveScrollWheelInputEvent(
+      const ScrollWheelInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, ScrollWheelInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvReceiveKeyboardInputEvent(
+      const KeyboardInput& aEvent, bool aWantsCallback,
+      APZEventResult* aOutResult, KeyboardInput* aOutEvent);
+
+  mozilla::ipc::IPCResult RecvUpdateWheelTransaction(
+      const LayoutDeviceIntPoint& aRefPoint, const EventMessage& aEventMessage,
+      const Maybe<ScrollableLayerGuid>& aTargetGuid);
+
+  mozilla::ipc::IPCResult RecvProcessUnhandledEvent(
+      const LayoutDeviceIntPoint& aRefPoint, LayoutDeviceIntPoint* aOutRefPoint,
+      ScrollableLayerGuid* aOutTargetGuid, uint64_t* aOutFocusSequenceNumber,
+      LayersId* aOutLayersId);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+ protected:
+  explicit APZInputBridgeParent(const LayersId& aLayersId);
+  virtual ~APZInputBridgeParent();
+
+ private:
+  RefPtr<IAPZCTreeManager> mTreeManager;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_APZInputBridgeParent_h
diff --git a/gfx/layers/ipc/ActiveResource.h b/gfx/layers/ipc/ActiveResource.h
new file mode 100644
index 0000000000..6e7db60541
--- /dev/null
+++ b/gfx/layers/ipc/ActiveResource.h
@@ -0,0 +1,45 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_ACTIVERESOURCE
+#define MOZILLA_LAYERS_ACTIVERESOURCE
+
+#include "nsExpirationTracker.h"
+
+namespace mozilla::layers {
+
+/**
+ * See ActiveResourceTracker below.
+ */
+class ActiveResource {
+ public:
+  virtual void NotifyInactive() = 0;
+  nsExpirationState* GetExpirationState() { return &mExpirationState; }
+  bool IsActivityTracked() { return mExpirationState.IsTracked(); }
+
+ private:
+  nsExpirationState mExpirationState;
+};
+
+/**
+ * A convenience class on top of nsExpirationTracker
+ */
+class ActiveResourceTracker final
+    : public nsExpirationTracker<ActiveResource, 3> {
+ public:
+  ActiveResourceTracker(uint32_t aExpirationCycle, const char* aName,
+                        nsIEventTarget* aEventTarget)
+      : nsExpirationTracker(aExpirationCycle, aName, aEventTarget) {}
+
+  void NotifyExpired(ActiveResource* aResource) override {
+    RemoveObject(aResource);
+    aResource->NotifyInactive();
+  }
+};
+
+}  // namespace mozilla::layers
+
+#endif
diff --git a/gfx/layers/ipc/CanvasChild.cpp b/gfx/layers/ipc/CanvasChild.cpp
new file mode 100644
index 0000000000..553217d82b
--- /dev/null
+++ b/gfx/layers/ipc/CanvasChild.cpp
@@ -0,0 +1,547 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CanvasChild.h"
+
+#include "MainThreadUtils.h"
+#include "mozilla/gfx/CanvasManagerChild.h"
+#include "mozilla/gfx/DrawTargetRecording.h"
+#include "mozilla/gfx/Tools.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/ipc/ProcessChild.h"
+#include "mozilla/layers/CanvasDrawEventRecorder.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/SourceSurfaceSharedData.h"
+#include "mozilla/Maybe.h"
+#include "nsIObserverService.h"
+#include "RecordedCanvasEventImpl.h"
+
+namespace mozilla {
+namespace layers {
+
+class RecorderHelpers final : public CanvasDrawEventRecorder::Helpers {
+ public:
+  NS_DECL_OWNINGTHREAD
+
+  explicit RecorderHelpers(const RefPtr<CanvasChild>& aCanvasChild)
+      : mCanvasChild(aCanvasChild) {}
+
+  ~RecorderHelpers() override = default;
+
+  bool InitTranslator(TextureType aTextureType, gfx::BackendType aBackendType,
+                      Handle&& aReadHandle, nsTArray<Handle>&& aBufferHandles,
+                      uint64_t aBufferSize,
+                      CrossProcessSemaphoreHandle&& aReaderSem,
+                      CrossProcessSemaphoreHandle&& aWriterSem) override {
+    NS_ASSERT_OWNINGTHREAD(RecorderHelpers);
+    if (NS_WARN_IF(!mCanvasChild)) {
+      return false;
+    }
+    return mCanvasChild->SendInitTranslator(
+        aTextureType, aBackendType, std::move(aReadHandle),
+        std::move(aBufferHandles), aBufferSize, std::move(aReaderSem),
+        std::move(aWriterSem));
+  }
+
+  bool AddBuffer(Handle&& aBufferHandle, uint64_t aBufferSize) override {
+    NS_ASSERT_OWNINGTHREAD(RecorderHelpers);
+    if (!mCanvasChild) {
+      return false;
+    }
+    return mCanvasChild->SendAddBuffer(std::move(aBufferHandle), aBufferSize);
+  }
+
+  bool ReaderClosed() override {
+    NS_ASSERT_OWNINGTHREAD(RecorderHelpers);
+    if (!mCanvasChild) {
+      return false;
+    }
+    return !mCanvasChild->CanSend() || ipc::ProcessChild::ExpectingShutdown();
+  }
+
+  bool RestartReader() override {
+    NS_ASSERT_OWNINGTHREAD(RecorderHelpers);
+    if (!mCanvasChild) {
+      return false;
+    }
+    return mCanvasChild->SendRestartTranslation();
+  }
+
+ private:
+  const WeakPtr<CanvasChild> mCanvasChild;
+};
+
+class SourceSurfaceCanvasRecording final : public gfx::SourceSurface {
+ public:
+  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(SourceSurfaceCanvasRecording, final)
+
+  SourceSurfaceCanvasRecording(
+      int64_t aTextureId, const RefPtr<gfx::SourceSurface>& aRecordedSuface,
+      CanvasChild* aCanvasChild,
+      const RefPtr<CanvasDrawEventRecorder>& aRecorder)
+      : mTextureId(aTextureId),
+        mRecordedSurface(aRecordedSuface),
+        mCanvasChild(aCanvasChild),
+        mRecorder(aRecorder) {
+    // It's important that AddStoredObject is called first because that will
+    // run any pending processing required by recorded objects that have been
+    // deleted off the main thread.
+    mRecorder->AddStoredObject(this);
+    mRecorder->RecordEvent(RecordedAddSurfaceAlias(this, aRecordedSuface));
+  }
+
+  ~SourceSurfaceCanvasRecording() {
+    ReferencePtr surfaceAlias = this;
+    if (NS_IsMainThread()) {
+      ReleaseOnMainThread(std::move(mRecorder), surfaceAlias,
+                          std::move(mRecordedSurface), std::move(mCanvasChild));
+      return;
+    }
+
+    mRecorder->AddPendingDeletion(
+        [recorder = std::move(mRecorder), surfaceAlias,
+         aliasedSurface = std::move(mRecordedSurface),
+         canvasChild = std::move(mCanvasChild)]() mutable -> void {
+          ReleaseOnMainThread(std::move(recorder), surfaceAlias,
+                              std::move(aliasedSurface),
+                              std::move(canvasChild));
+        });
+  }
+
+  gfx::SurfaceType GetType() const final { return mRecordedSurface->GetType(); }
+
+  gfx::IntSize GetSize() const final { return mRecordedSurface->GetSize(); }
+
+  gfx::SurfaceFormat GetFormat() const final {
+    return mRecordedSurface->GetFormat();
+  }
+
+  already_AddRefed<gfx::DataSourceSurface> GetDataSurface() final {
+    EnsureDataSurfaceOnMainThread();
+    return do_AddRef(mDataSourceSurface);
+  }
+
+  void AttachSurface() { mDetached = false; }
+  void DetachSurface() { mDetached = true; }
+
+  already_AddRefed<gfx::SourceSurface> ExtractSubrect(
+      const gfx::IntRect& aRect) final {
+    return mRecordedSurface->ExtractSubrect(aRect);
+  }
+
+ private:
+  void EnsureDataSurfaceOnMainThread() {
+    // The data can only be retrieved on the main thread.
+    if (!mDataSourceSurface && NS_IsMainThread()) {
+      mDataSourceSurface =
+          mCanvasChild->GetDataSurface(mTextureId, mRecordedSurface, mDetached);
+    }
+  }
+
+  // Used to ensure that clean-up that requires it is done on the main thread.
+  static void ReleaseOnMainThread(RefPtr<CanvasDrawEventRecorder> aRecorder,
+                                  ReferencePtr aSurfaceAlias,
+                                  RefPtr<gfx::SourceSurface> aAliasedSurface,
+                                  RefPtr<CanvasChild> aCanvasChild) {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    aRecorder->RemoveStoredObject(aSurfaceAlias);
+    aRecorder->RecordEvent(RecordedRemoveSurfaceAlias(aSurfaceAlias));
+    aAliasedSurface = nullptr;
+    aCanvasChild = nullptr;
+    aRecorder = nullptr;
+  }
+
+  int64_t mTextureId;
+  RefPtr<gfx::SourceSurface> mRecordedSurface;
+  RefPtr<CanvasChild> mCanvasChild;
+  RefPtr<CanvasDrawEventRecorder> mRecorder;
+  RefPtr<gfx::DataSourceSurface> mDataSourceSurface;
+  bool mDetached = false;
+};
+
+CanvasChild::CanvasChild() = default;
+
+CanvasChild::~CanvasChild() = default;
+
+static void NotifyCanvasDeviceReset() {
+  nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
+  if (obs) {
+    obs->NotifyObservers(nullptr, "canvas-device-reset", nullptr);
+  }
+}
+
+ipc::IPCResult CanvasChild::RecvNotifyDeviceChanged() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  NotifyCanvasDeviceReset();
+  mRecorder->RecordEvent(RecordedDeviceChangeAcknowledged());
+  return IPC_OK();
+}
+
+/* static */ bool CanvasChild::mDeactivated = false;
+
+ipc::IPCResult CanvasChild::RecvDeactivate() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  RefPtr<CanvasChild> self(this);
+  mDeactivated = true;
+  if (auto* cm = gfx::CanvasManagerChild::Get()) {
+    cm->DeactivateCanvas();
+  }
+  NotifyCanvasDeviceReset();
+  return IPC_OK();
+}
+
+ipc::IPCResult CanvasChild::RecvBlockCanvas() {
+  mBlocked = true;
+  if (auto* cm = gfx::CanvasManagerChild::Get()) {
+    cm->BlockCanvas();
+  }
+  return IPC_OK();
+}
+
+void CanvasChild::EnsureRecorder(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
+                                 TextureType aTextureType) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (!mRecorder) {
+    gfx::BackendType backendType =
+        gfxPlatform::GetPlatform()->GetPreferredCanvasBackend();
+    auto recorder = MakeRefPtr<CanvasDrawEventRecorder>();
+    if (!recorder->Init(aTextureType, backendType,
+                        MakeUnique<RecorderHelpers>(this))) {
+      return;
+    }
+
+    mRecorder = recorder.forget();
+  }
+
+  MOZ_RELEASE_ASSERT(mRecorder->GetTextureType() == aTextureType,
+                     "We only support one remote TextureType currently.");
+
+  EnsureDataSurfaceShmem(aSize, aFormat);
+}
+
+void CanvasChild::ActorDestroy(ActorDestroyReason aWhy) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (mRecorder) {
+    mRecorder->DetachResources();
+  }
+}
+
+void CanvasChild::Destroy() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (CanSend()) {
+    Send__delete__(this);
+  }
+}
+
+bool CanvasChild::EnsureBeginTransaction() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (!mIsInTransaction) {
+    RecordEvent(RecordedCanvasBeginTransaction());
+    mIsInTransaction = true;
+  }
+
+  return true;
+}
+
+void CanvasChild::EndTransaction() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (mIsInTransaction) {
+    RecordEvent(RecordedCanvasEndTransaction());
+    mIsInTransaction = false;
+    mDormant = false;
+  } else if (mRecorder) {
+    // Schedule to drop free buffers if we have no non-empty transactions.
+    if (!mDormant) {
+      mDormant = true;
+      NS_DelayedDispatchToCurrentThread(
+          NewRunnableMethod("CanvasChild::DropFreeBuffersWhenDormant", this,
+                            &CanvasChild::DropFreeBuffersWhenDormant),
+          StaticPrefs::gfx_canvas_remote_drop_buffer_milliseconds());
+    }
+  }
+
+  ++mTransactionsSinceGetDataSurface;
+}
+
+void CanvasChild::DropFreeBuffersWhenDormant() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+  // Drop any free buffers if we have not had any non-empty transactions.
+  if (mDormant && mRecorder) {
+    mRecorder->DropFreeBuffers();
+  }
+}
+
+void CanvasChild::ClearCachedResources() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+  if (mRecorder) {
+    mRecorder->DropFreeBuffers();
+    // Notify CanvasTranslator it is about to be minimized.
+    SendClearCachedResources();
+  }
+}
+
+bool CanvasChild::ShouldBeCleanedUp() const {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  // Always return true if we've been deactivated.
+  if (Deactivated()) {
+    return true;
+  }
+
+  // We can only be cleaned up if nothing else references our recorder.
+  return !mRecorder || mRecorder->hasOneRef();
+}
+
+already_AddRefed<gfx::DrawTargetRecording> CanvasChild::CreateDrawTarget(
+    int64_t aTextureId, const RemoteTextureOwnerId& aTextureOwnerId,
+    gfx::IntSize aSize, gfx::SurfaceFormat aFormat) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (!mRecorder) {
+    return nullptr;
+  }
+
+  RefPtr<gfx::DrawTarget> dummyDt = gfx::Factory::CreateDrawTarget(
+      gfx::BackendType::SKIA, gfx::IntSize(1, 1), aFormat);
+  RefPtr<gfx::DrawTargetRecording> dt = MakeAndAddRef<gfx::DrawTargetRecording>(
+      mRecorder, aTextureId, aTextureOwnerId, dummyDt, aSize);
+
+  mTextureInfo.insert({aTextureId, {}});
+
+  return dt.forget();
+}
+
+bool CanvasChild::EnsureDataSurfaceShmem(gfx::IntSize aSize,
+                                         gfx::SurfaceFormat aFormat) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (!mRecorder) {
+    return false;
+  }
+
+  size_t sizeRequired =
+      ImageDataSerializer::ComputeRGBBufferSize(aSize, aFormat);
+  if (!sizeRequired) {
+    return false;
+  }
+  sizeRequired = ipc::SharedMemory::PageAlignedSize(sizeRequired);
+
+  if (!mDataSurfaceShmemAvailable || mDataSurfaceShmem->Size() < sizeRequired) {
+    RecordEvent(RecordedPauseTranslation());
+    auto dataSurfaceShmem = MakeRefPtr<ipc::SharedMemoryBasic>();
+    if (!dataSurfaceShmem->Create(sizeRequired) ||
+        !dataSurfaceShmem->Map(sizeRequired)) {
+      return false;
+    }
+
+    auto shmemHandle = dataSurfaceShmem->TakeHandle();
+    if (!shmemHandle) {
+      return false;
+    }
+
+    if (!SendSetDataSurfaceBuffer(std::move(shmemHandle), sizeRequired)) {
+      return false;
+    }
+
+    mDataSurfaceShmem = dataSurfaceShmem.forget();
+    mDataSurfaceShmemAvailable = true;
+  }
+
+  MOZ_ASSERT(mDataSurfaceShmemAvailable);
+  return true;
+}
+
+void CanvasChild::RecordEvent(const gfx::RecordedEvent& aEvent) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  // We drop mRecorder in ActorDestroy to break the reference cycle.
+  if (!mRecorder) {
+    return;
+  }
+
+  mRecorder->RecordEvent(aEvent);
+}
+
+int64_t CanvasChild::CreateCheckpoint() {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+  return mRecorder->CreateCheckpoint();
+}
+
+already_AddRefed<gfx::DataSourceSurface> CanvasChild::GetDataSurface(
+    int64_t aTextureId, const gfx::SourceSurface* aSurface, bool aDetached) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+  MOZ_ASSERT(aSurface);
+
+  // mTransactionsSinceGetDataSurface is used to determine if we want to prepare
+  // a DataSourceSurface in the GPU process up front at the end of the
+  // transaction, but that only makes sense if the canvas JS is requesting data
+  // in between transactions.
+  if (!mIsInTransaction) {
+    mTransactionsSinceGetDataSurface = 0;
+  }
+
+  if (!EnsureBeginTransaction()) {
+    return nullptr;
+  }
+
+  // Shmem is only valid if the surface is the latest snapshot (not detached).
+  if (!aDetached) {
+    // If there is a shmem associated with this snapshot id, then we want to try
+    // use that directly without having to allocate a new shmem for retrieval.
+    auto it = mTextureInfo.find(aTextureId);
+    if (it != mTextureInfo.end() && it->second.mSnapshotShmem) {
+      const auto shmemPtr =
+          reinterpret_cast<uint8_t*>(it->second.mSnapshotShmem->memory());
+      MOZ_ASSERT(shmemPtr);
+      mRecorder->RecordEvent(RecordedPrepareShmem(aTextureId));
+      auto checkpoint = CreateCheckpoint();
+      if (NS_WARN_IF(!mRecorder->WaitForCheckpoint(checkpoint))) {
+        return nullptr;
+      }
+      gfx::IntSize size = aSurface->GetSize();
+      gfx::SurfaceFormat format = aSurface->GetFormat();
+      auto stride = ImageDataSerializer::ComputeRGBStride(format, size.width);
+      RefPtr<gfx::DataSourceSurface> dataSurface =
+          gfx::Factory::CreateWrappingDataSourceSurface(shmemPtr, stride, size,
+                                                        format);
+      return dataSurface.forget();
+    }
+  }
+
+  RecordEvent(RecordedPrepareDataForSurface(aSurface));
+
+  gfx::IntSize ssSize = aSurface->GetSize();
+  gfx::SurfaceFormat ssFormat = aSurface->GetFormat();
+  if (!EnsureDataSurfaceShmem(ssSize, ssFormat)) {
+    return nullptr;
+  }
+
+  RecordEvent(RecordedGetDataForSurface(aSurface));
+  auto checkpoint = CreateCheckpoint();
+  if (NS_WARN_IF(!mRecorder->WaitForCheckpoint(checkpoint))) {
+    return nullptr;
+  }
+
+  mDataSurfaceShmemAvailable = false;
+  struct DataShmemHolder {
+    RefPtr<ipc::SharedMemoryBasic> shmem;
+    RefPtr<CanvasChild> canvasChild;
+  };
+
+  auto* data = static_cast<uint8_t*>(mDataSurfaceShmem->memory());
+  auto* closure = new DataShmemHolder{do_AddRef(mDataSurfaceShmem), this};
+  auto stride = ImageDataSerializer::ComputeRGBStride(ssFormat, ssSize.width);
+
+  RefPtr<gfx::DataSourceSurface> dataSurface =
+      gfx::Factory::CreateWrappingDataSourceSurface(
+          data, stride, ssSize, ssFormat, ReleaseDataShmemHolder, closure);
+  return dataSurface.forget();
+}
+
+/* static */ void CanvasChild::ReleaseDataShmemHolder(void* aClosure) {
+  if (!NS_IsMainThread()) {
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "CanvasChild::ReleaseDataShmemHolder",
+        [aClosure]() { ReleaseDataShmemHolder(aClosure); }));
+    return;
+  }
+
+  auto* shmemHolder = static_cast<DataShmemHolder*>(aClosure);
+  shmemHolder->canvasChild->ReturnDataSurfaceShmem(shmemHolder->shmem.forget());
+  delete shmemHolder;
+}
+
+already_AddRefed<gfx::SourceSurface> CanvasChild::WrapSurface(
+    const RefPtr<gfx::SourceSurface>& aSurface, int64_t aTextureId) {
+  NS_ASSERT_OWNINGTHREAD(CanvasChild);
+
+  if (!aSurface) {
+    return nullptr;
+  }
+
+  return MakeAndAddRef<SourceSurfaceCanvasRecording>(aTextureId, aSurface, this,
+                                                     mRecorder);
+}
+
+void CanvasChild::ReturnDataSurfaceShmem(
+    already_AddRefed<ipc::SharedMemoryBasic> aDataSurfaceShmem) {
+  RefPtr<ipc::SharedMemoryBasic> data = aDataSurfaceShmem;
+  // We can only reuse the latest data surface shmem.
+  if (data == mDataSurfaceShmem) {
+    MOZ_ASSERT(!mDataSurfaceShmemAvailable);
+    mDataSurfaceShmemAvailable = true;
+  }
+}
+
+void CanvasChild::AttachSurface(const RefPtr<gfx::SourceSurface>& aSurface) {
+  if (auto* surface =
+          static_cast<SourceSurfaceCanvasRecording*>(aSurface.get())) {
+    surface->AttachSurface();
+  }
+}
+
+void CanvasChild::DetachSurface(const RefPtr<gfx::SourceSurface>& aSurface) {
+  if (auto* surface =
+          static_cast<SourceSurfaceCanvasRecording*>(aSurface.get())) {
+    surface->DetachSurface();
+  }
+}
+
+ipc::IPCResult CanvasChild::RecvNotifyRequiresRefresh(int64_t aTextureId) {
+  auto it = mTextureInfo.find(aTextureId);
+  if (it != mTextureInfo.end()) {
+    it->second.mRequiresRefresh = true;
+  }
+  return IPC_OK();
+}
+
+bool CanvasChild::RequiresRefresh(int64_t aTextureId) const {
+  if (mBlocked) {
+    return true;
+  }
+  auto it = mTextureInfo.find(aTextureId);
+  if (it != mTextureInfo.end()) {
+    return it->second.mRequiresRefresh;
+  }
+  return false;
+}
+
+ipc::IPCResult CanvasChild::RecvSnapshotShmem(
+    int64_t aTextureId, Handle&& aShmemHandle, uint32_t aShmemSize,
+    SnapshotShmemResolver&& aResolve) {
+  auto it = mTextureInfo.find(aTextureId);
+  if (it != mTextureInfo.end()) {
+    auto shmem = MakeRefPtr<ipc::SharedMemoryBasic>();
+    if (NS_WARN_IF(!shmem->SetHandle(std::move(aShmemHandle),
+                                     ipc::SharedMemory::RightsReadOnly)) ||
+        NS_WARN_IF(!shmem->Map(aShmemSize))) {
+      shmem = nullptr;
+    } else {
+      it->second.mSnapshotShmem = std::move(shmem);
+    }
+    aResolve(true);
+  } else {
+    aResolve(false);
+  }
+  return IPC_OK();
+}
+
+void CanvasChild::CleanupTexture(int64_t aTextureId) {
+  mTextureInfo.erase(aTextureId);
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CanvasChild.h b/gfx/layers/ipc/CanvasChild.h
new file mode 100644
index 0000000000..c99fe50bfb
--- /dev/null
+++ b/gfx/layers/ipc/CanvasChild.h
@@ -0,0 +1,195 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CanvasChild_h
+#define mozilla_layers_CanvasChild_h
+
+#include "mozilla/gfx/RecordedEvent.h"
+#include "mozilla/ipc/CrossProcessSemaphore.h"
+#include "mozilla/layers/PCanvasChild.h"
+#include "mozilla/layers/SourceSurfaceSharedData.h"
+#include "mozilla/WeakPtr.h"
+
+namespace mozilla {
+
+namespace gfx {
+class DrawTargetRecording;
+class SourceSurface;
+}
+
+namespace layers {
+class CanvasDrawEventRecorder;
+struct RemoteTextureOwnerId;
+
+class CanvasChild final : public PCanvasChild, public SupportsWeakPtr {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(CanvasChild)
+
+  CanvasChild();
+
+  /**
+   * @returns true if remote canvas has been deactivated due to failure.
+   */
+  static bool Deactivated() { return mDeactivated; }
+
+  /**
+   * Release resources until they are next required.
+   */
+  void ClearCachedResources();
+
+  ipc::IPCResult RecvNotifyDeviceChanged();
+
+  ipc::IPCResult RecvDeactivate();
+
+  ipc::IPCResult RecvBlockCanvas();
+
+  ipc::IPCResult RecvNotifyRequiresRefresh(int64_t aTextureId);
+
+  ipc::IPCResult RecvSnapshotShmem(int64_t aTextureId, Handle&& aShmemHandle,
+                                   uint32_t aShmemSize,
+                                   SnapshotShmemResolver&& aResolve);
+
+  /**
+   * Ensures that the DrawEventRecorder has been created.
+   *
+   * @params aTextureType the TextureType to create in the CanvasTranslator.
+   */
+  void EnsureRecorder(gfx::IntSize aSize, gfx::SurfaceFormat aFormat,
+                      TextureType aTextureType);
+
+  /**
+   * Clean up IPDL actor.
+   */
+  void Destroy();
+
+  /**
+   * @returns true if we should be caching data surfaces in the GPU process.
+   */
+  bool ShouldCacheDataSurface() const {
+    return mTransactionsSinceGetDataSurface < kCacheDataSurfaceThreshold;
+  }
+
+  /**
+   * Ensures that we have sent a begin transaction event, since the last
+   * end transaction.
+   * @returns false on failure to begin transaction
+   */
+  bool EnsureBeginTransaction();
+
+  /**
+   * Send an end transaction event to indicate the end of events for this frame.
+   */
+  void EndTransaction();
+
+  /**
+   * @returns true if the canvas IPC classes have not been used for some time
+   *          and can be cleaned up.
+   */
+  bool ShouldBeCleanedUp() const;
+
+  /**
+   * Create a DrawTargetRecording for a canvas texture.
+   * @param aTextureId the id of the new texture
+   * @param aSize size for the DrawTarget
+   * @param aFormat SurfaceFormat for the DrawTarget
+   * @returns newly created DrawTargetRecording
+   */
+  already_AddRefed<gfx::DrawTargetRecording> CreateDrawTarget(
+      int64_t aTextureId, const RemoteTextureOwnerId& aTextureOwnerId,
+      gfx::IntSize aSize, gfx::SurfaceFormat aFormat);
+
+  /**
+   * Record an event for processing by the CanvasParent's CanvasTranslator.
+   * @param aEvent the event to record
+   */
+  void RecordEvent(const gfx::RecordedEvent& aEvent);
+
+  int64_t CreateCheckpoint();
+
+  /**
+   * Wrap the given surface, so that we can provide a DataSourceSurface if
+   * required.
+   * @param aSurface the SourceSurface to wrap
+   * @param aTextureId the texture id of the source TextureData
+   * @returns a SourceSurface that can provide a DataSourceSurface if required
+   */
+  already_AddRefed<gfx::SourceSurface> WrapSurface(
+      const RefPtr<gfx::SourceSurface>& aSurface, int64_t aTextureId);
+
+  /**
+   * The DrawTargetRecording backing the surface has not been modified since the
+   * previous use, so it is safe to reattach the snapshot for readback.
+   */
+  void AttachSurface(const RefPtr<gfx::SourceSurface>& aSurface);
+
+  /**
+   * The DrawTargetRecording is about to change, so detach the old snapshot.
+   */
+  void DetachSurface(const RefPtr<gfx::SourceSurface>& aSurface);
+
+  /**
+   * Get DataSourceSurface from the translated equivalent version of aSurface in
+   * the GPU process.
+   * @param aTextureId the source TextureData to read from
+   * @param aSurface the SourceSurface in this process for which we need a
+   *                 DataSourceSurface
+   * @param aDetached whether the surface is old
+   * @returns a DataSourceSurface created from data for aSurface retrieve from
+   *          GPU process
+   */
+  already_AddRefed<gfx::DataSourceSurface> GetDataSurface(
+      int64_t aTextureId, const gfx::SourceSurface* aSurface, bool aDetached);
+
+  bool RequiresRefresh(int64_t aTextureId) const;
+
+  void CleanupTexture(int64_t aTextureId);
+
+ protected:
+  void ActorDestroy(ActorDestroyReason aWhy) final;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CanvasChild);
+
+  ~CanvasChild() final;
+
+  bool EnsureDataSurfaceShmem(gfx::IntSize aSize, gfx::SurfaceFormat aFormat);
+
+  void ReturnDataSurfaceShmem(
+      already_AddRefed<ipc::SharedMemoryBasic> aDataSurfaceShmem);
+
+  struct DataShmemHolder {
+    RefPtr<ipc::SharedMemoryBasic> shmem;
+    RefPtr<CanvasChild> canvasChild;
+  };
+
+  static void ReleaseDataShmemHolder(void* aClosure);
+
+  void DropFreeBuffersWhenDormant();
+
+  static const uint32_t kCacheDataSurfaceThreshold = 10;
+
+  static bool mDeactivated;
+
+  RefPtr<CanvasDrawEventRecorder> mRecorder;
+
+  RefPtr<ipc::SharedMemoryBasic> mDataSurfaceShmem;
+  bool mDataSurfaceShmemAvailable = false;
+  int64_t mLastWriteLockCheckpoint = 0;
+  uint32_t mTransactionsSinceGetDataSurface = kCacheDataSurfaceThreshold;
+  struct TextureInfo {
+    RefPtr<mozilla::ipc::SharedMemoryBasic> mSnapshotShmem;
+    bool mRequiresRefresh = false;
+  };
+  std::unordered_map<int64_t, TextureInfo> mTextureInfo;
+  bool mIsInTransaction = false;
+  bool mDormant = false;
+  bool mBlocked = false;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CanvasChild_h
diff --git a/gfx/layers/ipc/CanvasTranslator.cpp b/gfx/layers/ipc/CanvasTranslator.cpp
new file mode 100644
index 0000000000..08150d6952
--- /dev/null
+++ b/gfx/layers/ipc/CanvasTranslator.cpp
@@ -0,0 +1,1201 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#include "CanvasTranslator.h"
+
+#include "gfxGradientCache.h"
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/CanvasManagerParent.h"
+#include "mozilla/gfx/CanvasRenderThread.h"
+#include "mozilla/gfx/DrawTargetWebgl.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/gfx/GPUParent.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/BufferTexture.h"
+#include "mozilla/layers/CanvasTranslator.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/SharedSurfacesParent.h"
+#include "mozilla/layers/TextureClient.h"
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/SyncRunnable.h"
+#include "mozilla/TaskQueue.h"
+#include "mozilla/Telemetry.h"
+#include "GLContext.h"
+#include "RecordedCanvasEventImpl.h"
+
+#if defined(XP_WIN)
+#  include "mozilla/gfx/DeviceManagerDx.h"
+#  include "mozilla/layers/TextureD3D11.h"
+#endif
+
+namespace mozilla {
+namespace layers {
+
+UniquePtr<TextureData> CanvasTranslator::CreateTextureData(
+    const gfx::IntSize& aSize, gfx::SurfaceFormat aFormat, bool aClear) {
+  TextureData* textureData = nullptr;
+  TextureAllocationFlags allocFlags =
+      aClear ? ALLOC_CLEAR_BUFFER : ALLOC_DEFAULT;
+  switch (mTextureType) {
+#ifdef XP_WIN
+    case TextureType::D3D11: {
+      textureData =
+          D3D11TextureData::Create(aSize, aFormat, allocFlags, mDevice);
+      break;
+    }
+#endif
+    case TextureType::Unknown:
+      textureData = BufferTextureData::Create(
+          aSize, aFormat, gfx::BackendType::SKIA, LayersBackend::LAYERS_WR,
+          TextureFlags::DEALLOCATE_CLIENT | TextureFlags::REMOTE_TEXTURE,
+          allocFlags, nullptr);
+      break;
+    default:
+      textureData = TextureData::Create(mTextureType, aFormat, aSize,
+                                        allocFlags, mBackendType);
+      break;
+  }
+
+  return WrapUnique(textureData);
+}
+
+CanvasTranslator::CanvasTranslator(
+    layers::SharedSurfacesHolder* aSharedSurfacesHolder,
+    const dom::ContentParentId& aContentId, uint32_t aManagerId)
+    : mTranslationTaskQueue(gfx::CanvasRenderThread::CreateWorkerTaskQueue()),
+      mSharedSurfacesHolder(aSharedSurfacesHolder),
+      mMaxSpinCount(StaticPrefs::gfx_canvas_remote_max_spin_count()),
+      mContentId(aContentId),
+      mManagerId(aManagerId) {
+  mNextEventTimeout = TimeDuration::FromMilliseconds(
+      StaticPrefs::gfx_canvas_remote_event_timeout_ms());
+
+  // Track when remote canvas has been activated.
+  Telemetry::ScalarAdd(Telemetry::ScalarID::GFX_CANVAS_REMOTE_ACTIVATED, 1);
+}
+
+CanvasTranslator::~CanvasTranslator() = default;
+
+void CanvasTranslator::DispatchToTaskQueue(
+    already_AddRefed<nsIRunnable> aRunnable) {
+  if (mTranslationTaskQueue) {
+    MOZ_ALWAYS_SUCCEEDS(mTranslationTaskQueue->Dispatch(std::move(aRunnable)));
+  } else {
+    gfx::CanvasRenderThread::Dispatch(std::move(aRunnable));
+  }
+}
+
+bool CanvasTranslator::IsInTaskQueue() const {
+  if (mTranslationTaskQueue) {
+    return mTranslationTaskQueue->IsCurrentThreadIn();
+  }
+  return gfx::CanvasRenderThread::IsInCanvasRenderThread();
+}
+
+static bool CreateAndMapShmem(RefPtr<ipc::SharedMemoryBasic>& aShmem,
+                              Handle&& aHandle,
+                              ipc::SharedMemory::OpenRights aOpenRights,
+                              size_t aSize) {
+  auto shmem = MakeRefPtr<ipc::SharedMemoryBasic>();
+  if (!shmem->SetHandle(std::move(aHandle), aOpenRights) ||
+      !shmem->Map(aSize)) {
+    return false;
+  }
+
+  shmem->CloseHandle();
+  aShmem = shmem.forget();
+  return true;
+}
+
+bool CanvasTranslator::EnsureSharedContextWebgl() {
+  if (!mSharedContext || mSharedContext->IsContextLost()) {
+    if (mSharedContext) {
+      ForceDrawTargetWebglFallback();
+      if (mRemoteTextureOwner) {
+        // Ensure any shared surfaces referring to the old context go away.
+        mRemoteTextureOwner->ClearRecycledTextures();
+      }
+    }
+    mSharedContext = gfx::SharedContextWebgl::Create();
+    if (!mSharedContext || mSharedContext->IsContextLost()) {
+      mSharedContext = nullptr;
+      BlockCanvas();
+      return false;
+    }
+  }
+  return true;
+}
+
+mozilla::ipc::IPCResult CanvasTranslator::RecvInitTranslator(
+    TextureType aTextureType, gfx::BackendType aBackendType,
+    Handle&& aReadHandle, nsTArray<Handle>&& aBufferHandles,
+    uint64_t aBufferSize, CrossProcessSemaphoreHandle&& aReaderSem,
+    CrossProcessSemaphoreHandle&& aWriterSem) {
+  if (mHeaderShmem) {
+    return IPC_FAIL(this, "RecvInitTranslator called twice.");
+  }
+
+  mTextureType = aTextureType;
+  mBackendType = aBackendType;
+  mOtherPid = OtherPid();
+
+  mHeaderShmem = MakeAndAddRef<ipc::SharedMemoryBasic>();
+  if (!CreateAndMapShmem(mHeaderShmem, std::move(aReadHandle),
+                         ipc::SharedMemory::RightsReadWrite, sizeof(Header))) {
+    Deactivate();
+    return IPC_FAIL(this, "Failed to map canvas header shared memory.");
+  }
+
+  mHeader = static_cast<Header*>(mHeaderShmem->memory());
+
+  mWriterSemaphore.reset(CrossProcessSemaphore::Create(std::move(aWriterSem)));
+  mWriterSemaphore->CloseHandle();
+
+  mReaderSemaphore.reset(CrossProcessSemaphore::Create(std::move(aReaderSem)));
+  mReaderSemaphore->CloseHandle();
+
+  if (!CheckForFreshCanvasDevice(__LINE__)) {
+    gfxCriticalNote << "GFX: CanvasTranslator failed to get device";
+    return IPC_OK();
+  }
+
+  if (gfx::gfxVars::UseAcceleratedCanvas2D() && !EnsureSharedContextWebgl()) {
+    gfxCriticalNote
+        << "GFX: CanvasTranslator failed creating WebGL shared context";
+  }
+
+  // Use the first buffer as our current buffer.
+  mDefaultBufferSize = aBufferSize;
+  auto handleIter = aBufferHandles.begin();
+  if (!CreateAndMapShmem(mCurrentShmem.shmem, std::move(*handleIter),
+                         ipc::SharedMemory::RightsReadOnly, aBufferSize)) {
+    Deactivate();
+    return IPC_FAIL(this, "Failed to map canvas buffer shared memory.");
+  }
+  mCurrentMemReader = mCurrentShmem.CreateMemReader();
+
+  // Add all other buffers to our recycled CanvasShmems.
+  for (handleIter++; handleIter < aBufferHandles.end(); handleIter++) {
+    CanvasShmem newShmem;
+    if (!CreateAndMapShmem(newShmem.shmem, std::move(*handleIter),
+                           ipc::SharedMemory::RightsReadOnly, aBufferSize)) {
+      Deactivate();
+      return IPC_FAIL(this, "Failed to map canvas buffer shared memory.");
+    }
+    mCanvasShmems.emplace(std::move(newShmem));
+  }
+
+  DispatchToTaskQueue(NewRunnableMethod("CanvasTranslator::TranslateRecording",
+                                        this,
+                                        &CanvasTranslator::TranslateRecording));
+  return IPC_OK();
+}
+
+ipc::IPCResult CanvasTranslator::RecvRestartTranslation() {
+  if (mDeactivated) {
+    // The other side might have sent a message before we deactivated.
+    return IPC_OK();
+  }
+
+  DispatchToTaskQueue(NewRunnableMethod("CanvasTranslator::TranslateRecording",
+                                        this,
+                                        &CanvasTranslator::TranslateRecording));
+
+  return IPC_OK();
+}
+
+ipc::IPCResult CanvasTranslator::RecvAddBuffer(
+    ipc::SharedMemoryBasic::Handle&& aBufferHandle, uint64_t aBufferSize) {
+  if (mDeactivated) {
+    // The other side might have sent a resume message before we deactivated.
+    return IPC_OK();
+  }
+
+  DispatchToTaskQueue(
+      NewRunnableMethod<ipc::SharedMemoryBasic::Handle&&, size_t>(
+          "CanvasTranslator::AddBuffer", this, &CanvasTranslator::AddBuffer,
+          std::move(aBufferHandle), aBufferSize));
+
+  return IPC_OK();
+}
+
+void CanvasTranslator::AddBuffer(ipc::SharedMemoryBasic::Handle&& aBufferHandle,
+                                 size_t aBufferSize) {
+  MOZ_ASSERT(IsInTaskQueue());
+  if (mHeader->readerState == State::Failed) {
+    // We failed before we got to the pause event.
+    return;
+  }
+
+  if (mHeader->readerState != State::Paused) {
+    gfxCriticalNote << "CanvasTranslator::AddBuffer bad state "
+                    << uint32_t(State(mHeader->readerState));
+    MOZ_DIAGNOSTIC_ASSERT(false, "mHeader->readerState == State::Paused");
+    Deactivate();
+    return;
+  }
+
+  MOZ_ASSERT(mDefaultBufferSize != 0);
+
+  // Check and signal the writer when we finish with a buffer, because it
+  // might have hit the buffer count limit and be waiting to use our old one.
+  CheckAndSignalWriter();
+
+  // Default sized buffers will have been queued for recycling.
+  if (mCurrentShmem.Size() == mDefaultBufferSize) {
+    mCanvasShmems.emplace(std::move(mCurrentShmem));
+  }
+
+  CanvasShmem newShmem;
+  if (!CreateAndMapShmem(newShmem.shmem, std::move(aBufferHandle),
+                         ipc::SharedMemory::RightsReadOnly, aBufferSize)) {
+    return;
+  }
+
+  mCurrentShmem = std::move(newShmem);
+  mCurrentMemReader = mCurrentShmem.CreateMemReader();
+
+  TranslateRecording();
+}
+
+ipc::IPCResult CanvasTranslator::RecvSetDataSurfaceBuffer(
+    ipc::SharedMemoryBasic::Handle&& aBufferHandle, uint64_t aBufferSize) {
+  if (mDeactivated) {
+    // The other side might have sent a resume message before we deactivated.
+    return IPC_OK();
+  }
+
+  DispatchToTaskQueue(
+      NewRunnableMethod<ipc::SharedMemoryBasic::Handle&&, size_t>(
+          "CanvasTranslator::SetDataSurfaceBuffer", this,
+          &CanvasTranslator::SetDataSurfaceBuffer, std::move(aBufferHandle),
+          aBufferSize));
+
+  return IPC_OK();
+}
+
+void CanvasTranslator::SetDataSurfaceBuffer(
+    ipc::SharedMemoryBasic::Handle&& aBufferHandle, size_t aBufferSize) {
+  MOZ_ASSERT(IsInTaskQueue());
+  if (mHeader->readerState == State::Failed) {
+    // We failed before we got to the pause event.
+    return;
+  }
+
+  if (mHeader->readerState != State::Paused) {
+    gfxCriticalNote << "CanvasTranslator::SetDataSurfaceBuffer bad state "
+                    << uint32_t(State(mHeader->readerState));
+    MOZ_DIAGNOSTIC_ASSERT(false, "mHeader->readerState == State::Paused");
+    Deactivate();
+    return;
+  }
+
+  if (!CreateAndMapShmem(mDataSurfaceShmem, std::move(aBufferHandle),
+                         ipc::SharedMemory::RightsReadWrite, aBufferSize)) {
+    return;
+  }
+
+  TranslateRecording();
+}
+
+void CanvasTranslator::GetDataSurface(uint64_t aSurfaceRef) {
+  MOZ_ASSERT(IsInTaskQueue());
+
+  ReferencePtr surfaceRef = reinterpret_cast<void*>(aSurfaceRef);
+  gfx::SourceSurface* surface = LookupSourceSurface(surfaceRef);
+  if (!surface) {
+    return;
+  }
+
+  UniquePtr<gfx::DataSourceSurface::ScopedMap> map = GetPreparedMap(surfaceRef);
+  if (!map) {
+    return;
+  }
+
+  auto dstSize = surface->GetSize();
+  auto srcSize = map->GetSurface()->GetSize();
+  gfx::SurfaceFormat format = surface->GetFormat();
+  int32_t bpp = BytesPerPixel(format);
+  int32_t dataFormatWidth = dstSize.width * bpp;
+  int32_t srcStride = map->GetStride();
+  if (dataFormatWidth > srcStride || srcSize != dstSize) {
+    return;
+  }
+
+  int32_t dstStride =
+      ImageDataSerializer::ComputeRGBStride(format, dstSize.width);
+  auto requiredSize =
+      ImageDataSerializer::ComputeRGBBufferSize(dstSize, format);
+  if (requiredSize <= 0 || size_t(requiredSize) > mDataSurfaceShmem->Size()) {
+    return;
+  }
+
+  uint8_t* dst = static_cast<uint8_t*>(mDataSurfaceShmem->memory());
+  const uint8_t* src = map->GetData();
+  const uint8_t* endSrc = src + (srcSize.height * srcStride);
+  while (src < endSrc) {
+    memcpy(dst, src, dataFormatWidth);
+    src += srcStride;
+    dst += dstStride;
+  }
+}
+
+void CanvasTranslator::RecycleBuffer() {
+  mCanvasShmems.emplace(std::move(mCurrentShmem));
+  NextBuffer();
+}
+
+void CanvasTranslator::NextBuffer() {
+  // Check and signal the writer when we finish with a buffer, because it
+  // might have hit the buffer count limit and be waiting to use our old one.
+  CheckAndSignalWriter();
+
+  mCurrentShmem = std::move(mCanvasShmems.front());
+  mCanvasShmems.pop();
+  mCurrentMemReader = mCurrentShmem.CreateMemReader();
+}
+
+void CanvasTranslator::ActorDestroy(ActorDestroyReason why) {
+  MOZ_ASSERT(gfx::CanvasRenderThread::IsInCanvasRenderThread());
+
+  // Since we might need to access the actor status off the owning IPDL thread,
+  // we need to cache it here.
+  mIPDLClosed = true;
+
+  DispatchToTaskQueue(NewRunnableMethod("CanvasTranslator::ClearTextureInfo",
+                                        this,
+                                        &CanvasTranslator::ClearTextureInfo));
+
+  if (mTranslationTaskQueue) {
+    gfx::CanvasRenderThread::ShutdownWorkerTaskQueue(mTranslationTaskQueue);
+    return;
+  }
+}
+
+bool CanvasTranslator::CheckDeactivated() {
+  if (mDeactivated) {
+    return true;
+  }
+
+  if (NS_WARN_IF(!gfx::gfxVars::RemoteCanvasEnabled() &&
+                 !gfx::gfxVars::UseAcceleratedCanvas2D())) {
+    Deactivate();
+  }
+
+  return mDeactivated;
+}
+
+void CanvasTranslator::Deactivate() {
+  if (mDeactivated) {
+    return;
+  }
+  mDeactivated = true;
+  if (mHeader) {
+    mHeader->readerState = State::Failed;
+  }
+
+  // We need to tell the other side to deactivate. Make sure the stream is
+  // marked as bad so that the writing side won't wait for space to write.
+  gfx::CanvasRenderThread::Dispatch(
+      NewRunnableMethod("CanvasTranslator::SendDeactivate", this,
+                        &CanvasTranslator::SendDeactivate));
+
+  // Disable remote canvas for all.
+  gfx::CanvasManagerParent::DisableRemoteCanvas();
+}
+
+inline gfx::DrawTargetWebgl* CanvasTranslator::TextureInfo::GetDrawTargetWebgl(
+    bool aCheckForFallback) const {
+  if ((!mTextureData || !aCheckForFallback) && mDrawTarget &&
+      mDrawTarget->GetBackendType() == gfx::BackendType::WEBGL) {
+    return static_cast<gfx::DrawTargetWebgl*>(mDrawTarget.get());
+  }
+  return nullptr;
+}
+
+bool CanvasTranslator::TryDrawTargetWebglFallback(
+    int64_t aTextureId, gfx::DrawTargetWebgl* aWebgl) {
+  NotifyRequiresRefresh(aTextureId);
+
+  // An existing data snapshot is required for fallback, as we have to avoid
+  // trying to touch the WebGL context, which is assumed to be invalid and not
+  // suitable for readback.
+  if (!aWebgl->HasDataSnapshot()) {
+    return false;
+  }
+
+  const auto& info = mTextureInfo[aTextureId];
+  if (RefPtr<gfx::DrawTarget> dt = CreateFallbackDrawTarget(
+          info.mRefPtr, aTextureId, info.mRemoteTextureOwnerId,
+          aWebgl->GetSize(), aWebgl->GetFormat())) {
+    aWebgl->CopyToFallback(dt);
+    AddDrawTarget(info.mRefPtr, dt);
+    return true;
+  }
+  return false;
+}
+
+void CanvasTranslator::ForceDrawTargetWebglFallback() {
+  // This looks for any DrawTargetWebgls that have a cached data snapshot that
+  // can be used to recover a fallback TextureData in the event of a context
+  // loss.
+  RemoteTextureOwnerIdSet lost;
+  for (const auto& entry : mTextureInfo) {
+    const auto& info = entry.second;
+    if (gfx::DrawTargetWebgl* webgl = info.GetDrawTargetWebgl()) {
+      if (!TryDrawTargetWebglFallback(entry.first, webgl)) {
+        // No fallback could be created, so we need to notify the compositor the
+        // texture won't be pushed.
+        if (mRemoteTextureOwner &&
+            mRemoteTextureOwner->IsRegistered(info.mRemoteTextureOwnerId)) {
+          lost.insert(info.mRemoteTextureOwnerId);
+        }
+      }
+    }
+  }
+  if (!lost.empty()) {
+    mRemoteTextureOwner->NotifyContextLost(&lost);
+  }
+}
+
+void CanvasTranslator::BlockCanvas() {
+  if (mDeactivated || mBlocked) {
+    return;
+  }
+  mBlocked = true;
+  gfx::CanvasRenderThread::Dispatch(
+      NewRunnableMethod("CanvasTranslator::SendBlockCanvas", this,
+                        &CanvasTranslator::SendBlockCanvas));
+}
+
+void CanvasTranslator::CheckAndSignalWriter() {
+  do {
+    switch (mHeader->writerState) {
+      case State::Processing:
+      case State::Failed:
+        return;
+      case State::AboutToWait:
+        // The writer is making a decision about whether to wait. So, we must
+        // wait until it has decided to avoid races. Check if the writer is
+        // closed to avoid hangs.
+        if (mIPDLClosed) {
+          return;
+        }
+        continue;
+      case State::Waiting:
+        if (mHeader->processedCount >= mHeader->writerWaitCount) {
+          mHeader->writerState = State::Processing;
+          mWriterSemaphore->Signal();
+        }
+        return;
+      default:
+        MOZ_ASSERT_UNREACHABLE("Invalid waiting state.");
+        return;
+    }
+  } while (true);
+}
+
+bool CanvasTranslator::HasPendingEvent() {
+  return mHeader->processedCount < mHeader->eventCount;
+}
+
+bool CanvasTranslator::ReadPendingEvent(EventType& aEventType) {
+  ReadElementConstrained(mCurrentMemReader, aEventType,
+                         EventType::DRAWTARGETCREATION, LAST_CANVAS_EVENT_TYPE);
+  return mCurrentMemReader.good();
+}
+
+bool CanvasTranslator::ReadNextEvent(EventType& aEventType) {
+  if (mHeader->readerState == State::Paused) {
+    Flush();
+    return false;
+  }
+
+  uint32_t spinCount = mMaxSpinCount;
+  do {
+    if (HasPendingEvent()) {
+      return ReadPendingEvent(aEventType);
+    }
+  } while (--spinCount != 0);
+
+  Flush();
+  mHeader->readerState = State::AboutToWait;
+  if (HasPendingEvent()) {
+    mHeader->readerState = State::Processing;
+    return ReadPendingEvent(aEventType);
+  }
+
+  if (!mIsInTransaction) {
+    mHeader->readerState = State::Stopped;
+    return false;
+  }
+
+  // When in a transaction we wait for a short time because we're expecting more
+  // events from the content process. We don't want to wait for too long in case
+  // other content processes are waiting for events to process.
+  mHeader->readerState = State::Waiting;
+  if (mReaderSemaphore->Wait(Some(mNextEventTimeout))) {
+    MOZ_RELEASE_ASSERT(HasPendingEvent());
+    MOZ_RELEASE_ASSERT(mHeader->readerState == State::Processing);
+    return ReadPendingEvent(aEventType);
+  }
+
+  // We have to use compareExchange here because the writer can change our
+  // state if we are waiting.
+  if (!mHeader->readerState.compareExchange(State::Waiting, State::Stopped)) {
+    MOZ_RELEASE_ASSERT(HasPendingEvent());
+    MOZ_RELEASE_ASSERT(mHeader->readerState == State::Processing);
+    // The writer has just signaled us, so consume it before returning
+    MOZ_ALWAYS_TRUE(mReaderSemaphore->Wait());
+    return ReadPendingEvent(aEventType);
+  }
+
+  return false;
+}
+
+void CanvasTranslator::TranslateRecording() {
+  MOZ_ASSERT(IsInTaskQueue());
+
+  if (mSharedContext && EnsureSharedContextWebgl()) {
+    mSharedContext->EnterTlsScope();
+  }
+  auto exitTlsScope = MakeScopeExit([&] {
+    if (mSharedContext) {
+      mSharedContext->ExitTlsScope();
+    }
+  });
+
+  mHeader->readerState = State::Processing;
+  EventType eventType = EventType::INVALID;
+  while (ReadNextEvent(eventType)) {
+    bool success = RecordedEvent::DoWithEventFromReader(
+        mCurrentMemReader, eventType,
+        [&](RecordedEvent* recordedEvent) -> bool {
+          // Make sure that the whole event was read from the stream.
+          if (!mCurrentMemReader.good()) {
+            if (mIPDLClosed) {
+              // The other side has closed only warn about read failure.
+              gfxWarning() << "Failed to read event type: "
+                           << recordedEvent->GetType();
+            } else {
+              gfxCriticalNote << "Failed to read event type: "
+                              << recordedEvent->GetType();
+            }
+            mHeader->readerState = State::Failed;
+            return false;
+          }
+
+          return recordedEvent->PlayEvent(this);
+        });
+
+    // Check the stream is good here or we will log the issue twice.
+    if (!mCurrentMemReader.good()) {
+      return;
+    }
+
+    if (!success && !HandleExtensionEvent(eventType)) {
+      if (mDeviceResetInProgress) {
+        // We've notified the recorder of a device change, so we are expecting
+        // failures. Log as a warning to prevent crash reporting being flooded.
+        gfxWarning() << "Failed to play canvas event type: " << eventType;
+      } else {
+        gfxCriticalNote << "Failed to play canvas event type: " << eventType;
+      }
+      mHeader->readerState = State::Failed;
+    }
+
+    mHeader->processedCount++;
+  }
+}
+
+#define READ_AND_PLAY_CANVAS_EVENT_TYPE(_typeenum, _class)             \
+  case _typeenum: {                                                    \
+    auto e = _class(mCurrentMemReader);                                \
+    if (!mCurrentMemReader.good()) {                                   \
+      if (mIPDLClosed) {                                               \
+        /* The other side has closed only warn about read failure. */  \
+        gfxWarning() << "Failed to read event type: " << _typeenum;    \
+      } else {                                                         \
+        gfxCriticalNote << "Failed to read event type: " << _typeenum; \
+      }                                                                \
+      return false;                                                    \
+    }                                                                  \
+    return e.PlayCanvasEvent(this);                                    \
+  }
+
+bool CanvasTranslator::HandleExtensionEvent(int32_t aType) {
+  // This is where we handle extensions to the Moz2D Recording events to handle
+  // canvas specific things.
+  switch (aType) {
+    FOR_EACH_CANVAS_EVENT(READ_AND_PLAY_CANVAS_EVENT_TYPE)
+    default:
+      return false;
+  }
+}
+
+void CanvasTranslator::BeginTransaction() { mIsInTransaction = true; }
+
+void CanvasTranslator::Flush() {
+#if defined(XP_WIN)
+  // We can end up without a device, due to a reset and failure to re-create.
+  if (!mDevice) {
+    return;
+  }
+
+  gfx::AutoSerializeWithMoz2D serializeWithMoz2D(mBackendType);
+  RefPtr<ID3D11DeviceContext> deviceContext;
+  mDevice->GetImmediateContext(getter_AddRefs(deviceContext));
+  deviceContext->Flush();
+#endif
+}
+
+void CanvasTranslator::EndTransaction() {
+  Flush();
+  // At the end of a transaction is a good time to check if a new canvas device
+  // has been created, even if a reset did not occur.
+  Unused << CheckForFreshCanvasDevice(__LINE__);
+  mIsInTransaction = false;
+}
+
+void CanvasTranslator::DeviceChangeAcknowledged() {
+  mDeviceResetInProgress = false;
+  if (mRemoteTextureOwner) {
+    mRemoteTextureOwner->NotifyContextRestored();
+  }
+}
+
+bool CanvasTranslator::CreateReferenceTexture() {
+  if (mReferenceTextureData) {
+    mReferenceTextureData->Unlock();
+  }
+
+  mReferenceTextureData =
+      CreateTextureData(gfx::IntSize(1, 1), gfx::SurfaceFormat::B8G8R8A8, true);
+  if (!mReferenceTextureData) {
+    Deactivate();
+    return false;
+  }
+
+  if (NS_WARN_IF(!mReferenceTextureData->Lock(OpenMode::OPEN_READ_WRITE))) {
+    gfxCriticalNote << "CanvasTranslator::CreateReferenceTexture lock failed";
+    mReferenceTextureData.reset();
+    Deactivate();
+    return false;
+  }
+
+  mBaseDT = mReferenceTextureData->BorrowDrawTarget();
+
+  if (!mBaseDT) {
+    // We might get a null draw target due to a device failure, deactivate and
+    // return false so that we can recover.
+    Deactivate();
+    return false;
+  }
+
+  return true;
+}
+
+bool CanvasTranslator::CheckForFreshCanvasDevice(int aLineNumber) {
+  // If not on D3D11, we are not dependent on a fresh device for DT creation if
+  // one already exists.
+  if (mBaseDT && mTextureType != TextureType::D3D11) {
+    return false;
+  }
+
+#if defined(XP_WIN)
+  // If a new device has already been created, use that one.
+  RefPtr<ID3D11Device> device = gfx::DeviceManagerDx::Get()->GetCanvasDevice();
+  if (device && device != mDevice) {
+    if (mDevice) {
+      // We already had a device, notify child of change.
+      NotifyDeviceChanged();
+    }
+    mDevice = device.forget();
+    return CreateReferenceTexture();
+  }
+
+  if (mDevice) {
+    if (mDevice->GetDeviceRemovedReason() == S_OK) {
+      return false;
+    }
+
+    gfxCriticalNote << "GFX: CanvasTranslator detected a device reset at "
+                    << aLineNumber;
+    NotifyDeviceChanged();
+  }
+
+  RefPtr<Runnable> runnable = NS_NewRunnableFunction(
+      "CanvasTranslator NotifyDeviceReset",
+      []() { gfx::GPUParent::GetSingleton()->NotifyDeviceReset(); });
+
+  // It is safe to wait here because only the Compositor thread waits on us and
+  // the main thread doesn't wait on the compositor thread in the GPU process.
+  SyncRunnable::DispatchToThread(GetMainThreadSerialEventTarget(), runnable,
+                                 /*aForceDispatch*/ true);
+
+  mDevice = gfx::DeviceManagerDx::Get()->GetCanvasDevice();
+  if (!mDevice) {
+    // We don't have a canvas device, we need to deactivate.
+    Telemetry::ScalarAdd(
+        Telemetry::ScalarID::GFX_CANVAS_REMOTE_DEACTIVATED_NO_DEVICE, 1);
+    Deactivate();
+    return false;
+  }
+#endif
+
+  return CreateReferenceTexture();
+}
+
+void CanvasTranslator::NotifyDeviceChanged() {
+  // Clear out any old recycled texture datas with the wrong device.
+  if (mRemoteTextureOwner) {
+    mRemoteTextureOwner->NotifyContextLost();
+    mRemoteTextureOwner->ClearRecycledTextures();
+  }
+  mDeviceResetInProgress = true;
+  gfx::CanvasRenderThread::Dispatch(
+      NewRunnableMethod("CanvasTranslator::SendNotifyDeviceChanged", this,
+                        &CanvasTranslator::SendNotifyDeviceChanged));
+}
+
+gfx::DrawTargetWebgl* CanvasTranslator::GetDrawTargetWebgl(
+    int64_t aTextureId, bool aCheckForFallback) const {
+  auto result = mTextureInfo.find(aTextureId);
+  if (result != mTextureInfo.end()) {
+    return result->second.GetDrawTargetWebgl(aCheckForFallback);
+  }
+  return nullptr;
+}
+
+void CanvasTranslator::NotifyRequiresRefresh(int64_t aTextureId,
+                                             bool aDispatch) {
+  if (aDispatch) {
+    auto& info = mTextureInfo[aTextureId];
+    if (!info.mNotifiedRequiresRefresh) {
+      info.mNotifiedRequiresRefresh = true;
+      DispatchToTaskQueue(NewRunnableMethod<int64_t, bool>(
+          "CanvasTranslator::NotifyRequiresRefresh", this,
+          &CanvasTranslator::NotifyRequiresRefresh, aTextureId, false));
+    }
+    return;
+  }
+
+  if (mTextureInfo.find(aTextureId) != mTextureInfo.end()) {
+    Unused << SendNotifyRequiresRefresh(aTextureId);
+  }
+}
+
+void CanvasTranslator::CacheSnapshotShmem(int64_t aTextureId, bool aDispatch) {
+  if (aDispatch) {
+    DispatchToTaskQueue(NewRunnableMethod<int64_t, bool>(
+        "CanvasTranslator::CacheSnapshotShmem", this,
+        &CanvasTranslator::CacheSnapshotShmem, aTextureId, false));
+    return;
+  }
+
+  if (gfx::DrawTargetWebgl* webgl = GetDrawTargetWebgl(aTextureId)) {
+    if (auto shmemHandle = webgl->TakeShmemHandle()) {
+      // Lock the DT so that it doesn't get removed while shmem is in transit.
+      mTextureInfo[aTextureId].mLocked++;
+      nsCOMPtr<nsIThread> thread =
+          gfx::CanvasRenderThread::GetCanvasRenderThread();
+      RefPtr<CanvasTranslator> translator = this;
+      SendSnapshotShmem(aTextureId, std::move(shmemHandle),
+                        webgl->GetShmemSize())
+          ->Then(
+              thread, __func__,
+              [=](bool) { translator->RemoveTexture(aTextureId); },
+              [=](ipc::ResponseRejectReason) {
+                translator->RemoveTexture(aTextureId);
+              });
+    }
+  }
+}
+
+void CanvasTranslator::PrepareShmem(int64_t aTextureId) {
+  if (gfx::DrawTargetWebgl* webgl = GetDrawTargetWebgl(aTextureId, false)) {
+    if (const auto& fallback = mTextureInfo[aTextureId].mTextureData) {
+      // If there was a fallback, copy the fallback to the software framebuffer
+      // shmem for reading.
+      if (RefPtr<gfx::DrawTarget> dt = fallback->BorrowDrawTarget()) {
+        if (RefPtr<gfx::SourceSurface> snapshot = dt->Snapshot()) {
+          webgl->CopySurface(snapshot, snapshot->GetRect(),
+                             gfx::IntPoint(0, 0));
+        }
+      }
+    } else {
+      // Otherwise, just ensure the software framebuffer is up to date.
+      webgl->PrepareShmem();
+    }
+  }
+}
+
+void CanvasTranslator::ClearCachedResources() {
+  if (mSharedContext) {
+    // If there are any DrawTargetWebgls, then try to cache their framebuffers
+    // in software surfaces, just in case the GL context is lost. So long as
+    // there is a software copy of the framebuffer, it can be copied into a
+    // fallback TextureData later even if the GL context goes away.
+    mSharedContext->OnMemoryPressure();
+    for (auto const& entry : mTextureInfo) {
+      if (gfx::DrawTargetWebgl* webgl = entry.second.GetDrawTargetWebgl()) {
+        webgl->EnsureDataSnapshot();
+      }
+    }
+  }
+}
+
+ipc::IPCResult CanvasTranslator::RecvClearCachedResources() {
+  if (mDeactivated) {
+    // The other side might have sent a message before we deactivated.
+    return IPC_OK();
+  }
+
+  DispatchToTaskQueue(
+      NewRunnableMethod("CanvasTranslator::ClearCachedResources", this,
+                        &CanvasTranslator::ClearCachedResources));
+  return IPC_OK();
+}
+
+static const OpenMode kInitMode = OpenMode::OPEN_READ_WRITE;
+
+already_AddRefed<gfx::DrawTarget> CanvasTranslator::CreateFallbackDrawTarget(
+    gfx::ReferencePtr aRefPtr, int64_t aTextureId,
+    RemoteTextureOwnerId aTextureOwnerId, const gfx::IntSize& aSize,
+    gfx::SurfaceFormat aFormat) {
+  RefPtr<gfx::DrawTarget> dt;
+  do {
+    UniquePtr<TextureData> textureData =
+        CreateOrRecycleTextureData(aSize, aFormat);
+    if (NS_WARN_IF(!textureData)) {
+      continue;
+    }
+
+    if (NS_WARN_IF(!textureData->Lock(kInitMode))) {
+      gfxCriticalNote << "CanvasTranslator::CreateDrawTarget lock failed";
+      continue;
+    }
+
+    dt = textureData->BorrowDrawTarget();
+    if (NS_WARN_IF(!dt)) {
+      textureData->Unlock();
+      continue;
+    }
+    // Recycled buffer contents may be uninitialized.
+    dt->ClearRect(gfx::Rect(dt->GetRect()));
+
+    TextureInfo& info = mTextureInfo[aTextureId];
+    info.mRefPtr = aRefPtr;
+    info.mTextureData = std::move(textureData);
+    info.mRemoteTextureOwnerId = aTextureOwnerId;
+    info.mTextureLockMode = kInitMode;
+  } while (!dt && CheckForFreshCanvasDevice(__LINE__));
+  return dt.forget();
+}
+
+already_AddRefed<gfx::DrawTarget> CanvasTranslator::CreateDrawTarget(
+    gfx::ReferencePtr aRefPtr, int64_t aTextureId,
+    RemoteTextureOwnerId aTextureOwnerId, const gfx::IntSize& aSize,
+    gfx::SurfaceFormat aFormat) {
+  if (aTextureId < 0) {
+    MOZ_DIAGNOSTIC_ASSERT(false, "No texture ID set");
+    return nullptr;
+  }
+
+  if (!aTextureOwnerId.IsValid()) {
+    MOZ_DIAGNOSTIC_ASSERT(false, "No texture owner set");
+    return nullptr;
+  }
+
+  RefPtr<gfx::DrawTarget> dt;
+  if (gfx::gfxVars::UseAcceleratedCanvas2D()) {
+    if (EnsureSharedContextWebgl()) {
+      mSharedContext->EnterTlsScope();
+    }
+    if (RefPtr<gfx::DrawTargetWebgl> webgl =
+            gfx::DrawTargetWebgl::Create(aSize, aFormat, mSharedContext)) {
+      webgl->BeginFrame(true);
+      dt = webgl.forget().downcast<gfx::DrawTarget>();
+      if (dt) {
+        TextureInfo& info = mTextureInfo[aTextureId];
+        info.mRefPtr = aRefPtr;
+        info.mDrawTarget = dt;
+        info.mRemoteTextureOwnerId = aTextureOwnerId;
+        info.mTextureLockMode = kInitMode;
+        CacheSnapshotShmem(aTextureId);
+      }
+    }
+    if (!dt) {
+      NotifyRequiresRefresh(aTextureId);
+    }
+  }
+
+  if (!dt) {
+    dt = CreateFallbackDrawTarget(aRefPtr, aTextureId, aTextureOwnerId, aSize,
+                                  aFormat);
+  }
+
+  AddDrawTarget(aRefPtr, dt);
+  return dt.forget();
+}
+
+already_AddRefed<gfx::DrawTarget> CanvasTranslator::CreateDrawTarget(
+    gfx::ReferencePtr aRefPtr, const gfx::IntSize& aSize,
+    gfx::SurfaceFormat aFormat) {
+  MOZ_DIAGNOSTIC_ASSERT(false, "Unexpected CreateDrawTarget call!");
+  return nullptr;
+}
+
+void CanvasTranslator::RemoveTexture(int64_t aTextureId,
+                                     RemoteTextureTxnType aTxnType,
+                                     RemoteTextureTxnId aTxnId) {
+  // Don't erase the texture if still in use
+  auto result = mTextureInfo.find(aTextureId);
+  if (result == mTextureInfo.end()) {
+    return;
+  }
+  auto& info = result->second;
+  if (mRemoteTextureOwner && aTxnType && aTxnId) {
+    mRemoteTextureOwner->WaitForTxn(info.mRemoteTextureOwnerId, aTxnType,
+                                    aTxnId);
+  }
+  if (--info.mLocked > 0) {
+    return;
+  }
+  if (info.mTextureData) {
+    info.mTextureData->Unlock();
+  }
+  if (mRemoteTextureOwner) {
+    // If this texture id was manually registered as a remote texture owner,
+    // unregister it so it does not stick around after the texture id goes away.
+    RemoteTextureOwnerId owner = info.mRemoteTextureOwnerId;
+    if (owner.IsValid()) {
+      mRemoteTextureOwner->UnregisterTextureOwner(owner);
+    }
+  }
+  mTextureInfo.erase(result);
+}
+
+bool CanvasTranslator::LockTexture(int64_t aTextureId, OpenMode aMode,
+                                   bool aInvalidContents) {
+  if (aMode == OpenMode::OPEN_NONE) {
+    return false;
+  }
+  auto result = mTextureInfo.find(aTextureId);
+  if (result == mTextureInfo.end()) {
+    return false;
+  }
+  auto& info = result->second;
+  if (info.mTextureLockMode != OpenMode::OPEN_NONE) {
+    return (info.mTextureLockMode & aMode) == aMode;
+  }
+  if (gfx::DrawTargetWebgl* webgl = info.GetDrawTargetWebgl()) {
+    if (aMode & OpenMode::OPEN_WRITE) {
+      webgl->BeginFrame(aInvalidContents);
+    }
+  }
+  info.mTextureLockMode = aMode;
+  return true;
+}
+
+bool CanvasTranslator::UnlockTexture(int64_t aTextureId) {
+  auto result = mTextureInfo.find(aTextureId);
+  if (result == mTextureInfo.end()) {
+    return false;
+  }
+  auto& info = result->second;
+  if (info.mTextureLockMode == OpenMode::OPEN_NONE) {
+    return false;
+  }
+
+  if (gfx::DrawTargetWebgl* webgl = info.GetDrawTargetWebgl()) {
+    if (info.mTextureLockMode & OpenMode::OPEN_WRITE) {
+      webgl->EndFrame();
+      if (webgl->RequiresRefresh()) {
+        NotifyRequiresRefresh(aTextureId);
+      }
+    }
+  }
+  info.mTextureLockMode = OpenMode::OPEN_NONE;
+  return true;
+}
+
+bool CanvasTranslator::PresentTexture(int64_t aTextureId, RemoteTextureId aId) {
+  auto result = mTextureInfo.find(aTextureId);
+  if (result == mTextureInfo.end()) {
+    return false;
+  }
+  auto& info = result->second;
+  RemoteTextureOwnerId ownerId = info.mRemoteTextureOwnerId;
+  if (gfx::DrawTargetWebgl* webgl = info.GetDrawTargetWebgl()) {
+    EnsureRemoteTextureOwner(ownerId);
+    if (webgl->CopyToSwapChain(aId, ownerId, mRemoteTextureOwner)) {
+      return true;
+    }
+    if (mSharedContext && mSharedContext->IsContextLost()) {
+      // If the context was lost, try to create a fallback to push instead.
+      EnsureSharedContextWebgl();
+    } else {
+      // CopyToSwapChain failed for an unknown reason other than context loss.
+      // Try to read into fallback data if possible to recover, otherwise force
+      // the loss of the individual texture.
+      webgl->EnsureDataSnapshot();
+      if (!TryDrawTargetWebglFallback(aTextureId, webgl)) {
+        RemoteTextureOwnerIdSet lost = {info.mRemoteTextureOwnerId};
+        mRemoteTextureOwner->NotifyContextLost(&lost);
+      }
+    }
+  }
+  if (TextureData* data = info.mTextureData.get()) {
+    PushRemoteTexture(aTextureId, data, aId, ownerId);
+  }
+  return true;
+}
+
+void CanvasTranslator::EnsureRemoteTextureOwner(RemoteTextureOwnerId aOwnerId) {
+  if (!mRemoteTextureOwner) {
+    mRemoteTextureOwner = new RemoteTextureOwnerClient(mOtherPid);
+  }
+  if (aOwnerId.IsValid() && !mRemoteTextureOwner->IsRegistered(aOwnerId)) {
+    mRemoteTextureOwner->RegisterTextureOwner(aOwnerId,
+                                              /* aSharedRecycling */ true);
+  }
+}
+
+UniquePtr<TextureData> CanvasTranslator::CreateOrRecycleTextureData(
+    const gfx::IntSize& aSize, gfx::SurfaceFormat aFormat) {
+  if (mRemoteTextureOwner) {
+    if (mTextureType == TextureType::Unknown) {
+      return mRemoteTextureOwner->CreateOrRecycleBufferTextureData(aSize,
+                                                                   aFormat);
+    }
+    if (UniquePtr<TextureData> data =
+            mRemoteTextureOwner->GetRecycledTextureData(aSize, aFormat,
+                                                        mTextureType)) {
+      return data;
+    }
+  }
+  return CreateTextureData(aSize, aFormat, false);
+}
+
+bool CanvasTranslator::PushRemoteTexture(int64_t aTextureId, TextureData* aData,
+                                         RemoteTextureId aId,
+                                         RemoteTextureOwnerId aOwnerId) {
+  EnsureRemoteTextureOwner(aOwnerId);
+  UniquePtr<TextureData> dstData;
+  if (!mDeviceResetInProgress) {
+    TextureData::Info info;
+    aData->FillInfo(info);
+    dstData = CreateOrRecycleTextureData(info.size, info.format);
+  }
+  bool success = false;
+  // Source data is already locked.
+  if (dstData) {
+    if (dstData->Lock(OpenMode::OPEN_WRITE)) {
+      if (RefPtr<gfx::DrawTarget> dstDT = dstData->BorrowDrawTarget()) {
+        if (RefPtr<gfx::DrawTarget> srcDT = aData->BorrowDrawTarget()) {
+          if (RefPtr<gfx::SourceSurface> snapshot = srcDT->Snapshot()) {
+            dstDT->CopySurface(snapshot, snapshot->GetRect(),
+                               gfx::IntPoint(0, 0));
+            dstDT->Flush();
+            success = true;
+          }
+        }
+      }
+      dstData->Unlock();
+    } else {
+      gfxCriticalNote << "CanvasTranslator::PushRemoteTexture dst lock failed";
+    }
+  }
+  if (success) {
+    mRemoteTextureOwner->PushTexture(aId, aOwnerId, std::move(dstData));
+  } else {
+    mRemoteTextureOwner->PushDummyTexture(aId, aOwnerId);
+  }
+  return success;
+}
+
+void CanvasTranslator::ClearTextureInfo() {
+  for (auto const& entry : mTextureInfo) {
+    if (entry.second.mTextureData) {
+      entry.second.mTextureData->Unlock();
+    }
+  }
+  mTextureInfo.clear();
+  mDrawTargets.Clear();
+  mSharedContext = nullptr;
+  mBaseDT = nullptr;
+  if (mReferenceTextureData) {
+    mReferenceTextureData->Unlock();
+  }
+  if (mRemoteTextureOwner) {
+    mRemoteTextureOwner->UnregisterAllTextureOwners();
+    mRemoteTextureOwner = nullptr;
+  }
+  if (mTranslationTaskQueue) {
+    gfx::CanvasRenderThread::FinishShutdownWorkerTaskQueue(
+        mTranslationTaskQueue);
+  }
+}
+
+already_AddRefed<gfx::SourceSurface> CanvasTranslator::LookupExternalSurface(
+    uint64_t aKey) {
+  return mSharedSurfacesHolder->Get(wr::ToExternalImageId(aKey));
+}
+
+void CanvasTranslator::CheckpointReached() { CheckAndSignalWriter(); }
+
+void CanvasTranslator::PauseTranslation() {
+  mHeader->readerState = State::Paused;
+}
+
+already_AddRefed<gfx::GradientStops> CanvasTranslator::GetOrCreateGradientStops(
+    gfx::DrawTarget* aDrawTarget, gfx::GradientStop* aRawStops,
+    uint32_t aNumStops, gfx::ExtendMode aExtendMode) {
+  MOZ_ASSERT(aDrawTarget);
+  nsTArray<gfx::GradientStop> rawStopArray(aRawStops, aNumStops);
+  return gfx::gfxGradientCache::GetOrCreateGradientStops(
+      aDrawTarget, rawStopArray, aExtendMode);
+}
+
+gfx::DataSourceSurface* CanvasTranslator::LookupDataSurface(
+    gfx::ReferencePtr aRefPtr) {
+  return mDataSurfaces.GetWeak(aRefPtr);
+}
+
+void CanvasTranslator::AddDataSurface(
+    gfx::ReferencePtr aRefPtr, RefPtr<gfx::DataSourceSurface>&& aSurface) {
+  mDataSurfaces.InsertOrUpdate(aRefPtr, std::move(aSurface));
+}
+
+void CanvasTranslator::RemoveDataSurface(gfx::ReferencePtr aRefPtr) {
+  mDataSurfaces.Remove(aRefPtr);
+}
+
+void CanvasTranslator::SetPreparedMap(
+    gfx::ReferencePtr aSurface,
+    UniquePtr<gfx::DataSourceSurface::ScopedMap> aMap) {
+  mMappedSurface = aSurface;
+  mPreparedMap = std::move(aMap);
+}
+
+UniquePtr<gfx::DataSourceSurface::ScopedMap> CanvasTranslator::GetPreparedMap(
+    gfx::ReferencePtr aSurface) {
+  if (!mPreparedMap) {
+    // We might fail to set the map during, for example, device resets.
+    return nullptr;
+  }
+
+  MOZ_RELEASE_ASSERT(mMappedSurface == aSurface,
+                     "aSurface must match previously stored surface.");
+
+  mMappedSurface = nullptr;
+  return std::move(mPreparedMap);
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CanvasTranslator.h b/gfx/layers/ipc/CanvasTranslator.h
new file mode 100644
index 0000000000..cf87b7ab53
--- /dev/null
+++ b/gfx/layers/ipc/CanvasTranslator.h
@@ -0,0 +1,395 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CanvasTranslator_h
+#define mozilla_layers_CanvasTranslator_h
+
+#include <unordered_map>
+#include <vector>
+
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/gfx/InlineTranslator.h"
+#include "mozilla/gfx/RecordedEvent.h"
+#include "CanvasChild.h"
+#include "mozilla/layers/CanvasDrawEventRecorder.h"
+#include "mozilla/layers/LayersSurfaces.h"
+#include "mozilla/layers/PCanvasParent.h"
+#include "mozilla/layers/RemoteTextureMap.h"
+#include "mozilla/ipc/CrossProcessSemaphore.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla {
+
+using EventType = gfx::RecordedEvent::EventType;
+class TaskQueue;
+
+namespace gfx {
+class DrawTargetWebgl;
+class SharedContextWebgl;
+}  // namespace gfx
+
+namespace layers {
+
+class SharedSurfacesHolder;
+class TextureData;
+
+class CanvasTranslator final : public gfx::InlineTranslator,
+                               public PCanvasParent {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CanvasTranslator)
+
+  friend class PProtocolParent;
+
+  CanvasTranslator(layers::SharedSurfacesHolder* aSharedSurfacesHolder,
+                   const dom::ContentParentId& aContentId, uint32_t aManagerId);
+
+  const dom::ContentParentId& GetContentId() const { return mContentId; }
+
+  uint32_t GetManagerId() const { return mManagerId; }
+
+  /**
+   * Dispatches a runnable to the preferred task queue or thread.
+   *
+   * @param aRunnable the runnable to dispatch
+   */
+  void DispatchToTaskQueue(already_AddRefed<nsIRunnable> aRunnable);
+
+  /**
+   * @returns true if running in the preferred task queue or thread for
+   * translation.
+   */
+  bool IsInTaskQueue() const;
+
+  /**
+   * Initialize the canvas translator for a particular TextureType and
+   * CanvasEventRingBuffer.
+   *
+   * @param aTextureType the TextureType the translator will create
+   * @param aBackendType the BackendType for texture data
+   * @param aHeaderHandle handle for the control header
+   * @param aBufferHandles handles for the initial buffers for translation
+   * @param aBufferSize size of buffers and the default size
+   * @param aReaderSem reading blocked semaphore for the CanvasEventRingBuffer
+   * @param aWriterSem writing blocked semaphore for the CanvasEventRingBuffer
+   */
+  ipc::IPCResult RecvInitTranslator(TextureType aTextureType,
+                                    gfx::BackendType aBackendType,
+                                    Handle&& aReadHandle,
+                                    nsTArray<Handle>&& aBufferHandles,
+                                    uint64_t aBufferSize,
+                                    CrossProcessSemaphoreHandle&& aReaderSem,
+                                    CrossProcessSemaphoreHandle&& aWriterSem);
+
+  /**
+   * Restart the translation from a Stopped state.
+   */
+  ipc::IPCResult RecvRestartTranslation();
+
+  /**
+   * Adds a new buffer to be translated. The current buffer will be recycled if
+   * it is of the default size. The translation will then be restarted.
+   */
+  ipc::IPCResult RecvAddBuffer(Handle&& aBufferHandle, uint64_t aBufferSize);
+
+  /**
+   * Sets the shared memory to be used for readback.
+   */
+  ipc::IPCResult RecvSetDataSurfaceBuffer(Handle&& aBufferHandle,
+                                          uint64_t aBufferSize);
+
+  ipc::IPCResult RecvClearCachedResources();
+
+  void ActorDestroy(ActorDestroyReason why) final;
+
+  void CheckAndSignalWriter();
+
+  /**
+   * Translates events until no more are available or the end of a transaction
+   * If this returns false the caller of this is responsible for re-calling
+   * this function.
+   */
+  void TranslateRecording();
+
+  /**
+   * Marks the beginning of rendering for a transaction. While in a transaction
+   * the translator will wait for a short time for events before returning.
+   * When not in a transaction the translator will only translate one event at a
+   * time.
+   */
+  void BeginTransaction();
+
+  /**
+   * Marks the end of a transaction.
+   */
+  void EndTransaction();
+
+  /**
+   * Flushes canvas drawing, for example to a device.
+   */
+  void Flush();
+
+  /**
+   * Marks that device change processing in the writing process has finished.
+   */
+  void DeviceChangeAcknowledged();
+
+  /**
+   * Used during playback of events to create DrawTargets. For the
+   * CanvasTranslator this means creating TextureDatas and getting the
+   * DrawTargets from those.
+   *
+   * @param aRefPtr the key to store the created DrawTarget against
+   * @param aTextureId texture ID for this DrawTarget
+   * @param aTextureOwnerId texture owner ID for this DrawTarget
+   * @param aSize the size of the DrawTarget
+   * @param aFormat the surface format for the DrawTarget
+   * @returns the new DrawTarget
+   */
+  already_AddRefed<gfx::DrawTarget> CreateDrawTarget(
+      gfx::ReferencePtr aRefPtr, int64_t aTextureId,
+      RemoteTextureOwnerId aTextureOwnerId, const gfx::IntSize& aSize,
+      gfx::SurfaceFormat aFormat);
+
+  already_AddRefed<gfx::DrawTarget> CreateDrawTarget(
+      gfx::ReferencePtr aRefPtr, const gfx::IntSize& aSize,
+      gfx::SurfaceFormat aFormat) final;
+
+  already_AddRefed<gfx::GradientStops> GetOrCreateGradientStops(
+      gfx::DrawTarget* aDrawTarget, gfx::GradientStop* aRawStops,
+      uint32_t aNumStops, gfx::ExtendMode aExtendMode) final;
+
+  void CheckpointReached();
+
+  void PauseTranslation();
+
+  /**
+   * Removes the texture and other objects associated with a texture ID.
+   *
+   * @param aTextureId the texture ID to remove
+   */
+  void RemoveTexture(int64_t aTextureId, RemoteTextureTxnType aTxnType = 0,
+                     RemoteTextureTxnId aTxnId = 0);
+
+  bool LockTexture(int64_t aTextureId, OpenMode aMode,
+                   bool aInvalidContents = false);
+  bool UnlockTexture(int64_t aTextureId);
+
+  bool PresentTexture(int64_t aTextureId, RemoteTextureId aId);
+
+  bool PushRemoteTexture(int64_t aTextureId, TextureData* aData,
+                         RemoteTextureId aId, RemoteTextureOwnerId aOwnerId);
+
+  /**
+   * Overriden to remove any DataSourceSurfaces associated with the RefPtr.
+   *
+   * @param aRefPtr the key to the surface
+   * @param aSurface the surface to store
+   */
+  void AddSourceSurface(gfx::ReferencePtr aRefPtr,
+                        gfx::SourceSurface* aSurface) final {
+    if (mMappedSurface == aRefPtr) {
+      mPreparedMap = nullptr;
+      mMappedSurface = nullptr;
+    }
+    RemoveDataSurface(aRefPtr);
+    InlineTranslator::AddSourceSurface(aRefPtr, aSurface);
+  }
+
+  /**
+   * Removes the SourceSurface and other objects associated with a SourceSurface
+   * from another process.
+   *
+   * @param aRefPtr the key to the objects to remove
+   */
+  void RemoveSourceSurface(gfx::ReferencePtr aRefPtr) final {
+    if (mMappedSurface == aRefPtr) {
+      mPreparedMap = nullptr;
+      mMappedSurface = nullptr;
+    }
+    RemoveDataSurface(aRefPtr);
+    InlineTranslator::RemoveSourceSurface(aRefPtr);
+  }
+
+  already_AddRefed<gfx::SourceSurface> LookupExternalSurface(
+      uint64_t aKey) final;
+
+  /**
+   * Gets the cached DataSourceSurface, if it exists, associated with a
+   * SourceSurface from another process.
+   *
+   * @param aRefPtr the key used to find the DataSourceSurface
+   * @returns the DataSourceSurface or nullptr if not found
+   */
+  gfx::DataSourceSurface* LookupDataSurface(gfx::ReferencePtr aRefPtr);
+
+  /**
+   * Used to cache the DataSourceSurface from a SourceSurface associated with a
+   * SourceSurface from another process. This is to improve performance if we
+   * require the data for that SourceSurface.
+   *
+   * @param aRefPtr the key used to store the DataSourceSurface
+   * @param aSurface the DataSourceSurface to store
+   */
+  void AddDataSurface(gfx::ReferencePtr aRefPtr,
+                      RefPtr<gfx::DataSourceSurface>&& aSurface);
+
+  /**
+   * Gets the cached DataSourceSurface, if it exists, associated with a
+   * SourceSurface from another process.
+   *
+   * @param aRefPtr the key used to find the DataSourceSurface
+   * @returns the DataSourceSurface or nullptr if not found
+   */
+  void RemoveDataSurface(gfx::ReferencePtr aRefPtr);
+
+  /**
+   * Sets a ScopedMap, to be used in a later event.
+   *
+   * @param aSurface the associated surface in the other process
+   * @param aMap the ScopedMap to store
+   */
+  void SetPreparedMap(gfx::ReferencePtr aSurface,
+                      UniquePtr<gfx::DataSourceSurface::ScopedMap> aMap);
+
+  /**
+   * Gets the ScopedMap stored using SetPreparedMap.
+   *
+   * @param aSurface must match the surface from the SetPreparedMap call
+   * @returns the ScopedMap if aSurface matches otherwise nullptr
+   */
+  UniquePtr<gfx::DataSourceSurface::ScopedMap> GetPreparedMap(
+      gfx::ReferencePtr aSurface);
+
+  void PrepareShmem(int64_t aTextureId);
+
+  void RecycleBuffer();
+
+  void NextBuffer();
+
+  void GetDataSurface(uint64_t aSurfaceRef);
+
+ private:
+  ~CanvasTranslator();
+
+  void AddBuffer(Handle&& aBufferHandle, size_t aBufferSize);
+
+  void SetDataSurfaceBuffer(Handle&& aBufferHandle, size_t aBufferSize);
+
+  bool ReadNextEvent(EventType& aEventType);
+
+  bool HasPendingEvent();
+
+  bool ReadPendingEvent(EventType& aEventType);
+
+  bool CheckDeactivated();
+
+  void Deactivate();
+
+  bool TryDrawTargetWebglFallback(int64_t aTextureId,
+                                  gfx::DrawTargetWebgl* aWebgl);
+  void ForceDrawTargetWebglFallback();
+
+  void BlockCanvas();
+
+  UniquePtr<TextureData> CreateTextureData(const gfx::IntSize& aSize,
+                                           gfx::SurfaceFormat aFormat,
+                                           bool aClear);
+
+  void EnsureRemoteTextureOwner(
+      RemoteTextureOwnerId aOwnerId = RemoteTextureOwnerId());
+
+  UniquePtr<TextureData> CreateOrRecycleTextureData(const gfx::IntSize& aSize,
+                                                    gfx::SurfaceFormat aFormat);
+
+  already_AddRefed<gfx::DrawTarget> CreateFallbackDrawTarget(
+      gfx::ReferencePtr aRefPtr, int64_t aTextureId,
+      RemoteTextureOwnerId aTextureOwnerId, const gfx::IntSize& aSize,
+      gfx::SurfaceFormat aFormat);
+
+  void ClearTextureInfo();
+
+  bool HandleExtensionEvent(int32_t aType);
+
+  bool CreateReferenceTexture();
+  bool CheckForFreshCanvasDevice(int aLineNumber);
+  void NotifyDeviceChanged();
+
+  bool EnsureSharedContextWebgl();
+  gfx::DrawTargetWebgl* GetDrawTargetWebgl(int64_t aTextureId,
+                                           bool aCheckForFallback = true) const;
+  void NotifyRequiresRefresh(int64_t aTextureId, bool aDispatch = true);
+  void CacheSnapshotShmem(int64_t aTextureId, bool aDispatch = true);
+
+  void ClearCachedResources();
+
+  const RefPtr<TaskQueue> mTranslationTaskQueue;
+  const RefPtr<SharedSurfacesHolder> mSharedSurfacesHolder;
+#if defined(XP_WIN)
+  RefPtr<ID3D11Device> mDevice;
+#endif
+  RefPtr<gfx::SharedContextWebgl> mSharedContext;
+  RefPtr<RemoteTextureOwnerClient> mRemoteTextureOwner;
+
+  size_t mDefaultBufferSize = 0;
+  uint32_t mMaxSpinCount;
+  TimeDuration mNextEventTimeout;
+
+  using State = CanvasDrawEventRecorder::State;
+  using Header = CanvasDrawEventRecorder::Header;
+
+  RefPtr<ipc::SharedMemoryBasic> mHeaderShmem;
+  Header* mHeader = nullptr;
+
+  struct CanvasShmem {
+    RefPtr<ipc::SharedMemoryBasic> shmem;
+    auto Size() { return shmem->Size(); }
+    gfx::MemReader CreateMemReader() {
+      return {static_cast<char*>(shmem->memory()), Size()};
+    }
+  };
+  std::queue<CanvasShmem> mCanvasShmems;
+  CanvasShmem mCurrentShmem;
+  gfx::MemReader mCurrentMemReader{0, 0};
+  RefPtr<ipc::SharedMemoryBasic> mDataSurfaceShmem;
+  UniquePtr<CrossProcessSemaphore> mWriterSemaphore;
+  UniquePtr<CrossProcessSemaphore> mReaderSemaphore;
+  TextureType mTextureType = TextureType::Unknown;
+  UniquePtr<TextureData> mReferenceTextureData;
+  dom::ContentParentId mContentId;
+  uint32_t mManagerId;
+  // Sometimes during device reset our reference DrawTarget can be null, so we
+  // hold the BackendType separately.
+  gfx::BackendType mBackendType = gfx::BackendType::NONE;
+  base::ProcessId mOtherPid = base::kInvalidProcessId;
+  struct TextureInfo {
+    gfx::ReferencePtr mRefPtr;
+    UniquePtr<TextureData> mTextureData;
+    RefPtr<gfx::DrawTarget> mDrawTarget;
+    RemoteTextureOwnerId mRemoteTextureOwnerId;
+    bool mNotifiedRequiresRefresh = false;
+    // Ref-count of how active uses of the DT. Avoids deletion when locked.
+    int32_t mLocked = 1;
+    OpenMode mTextureLockMode = OpenMode::OPEN_NONE;
+
+    gfx::DrawTargetWebgl* GetDrawTargetWebgl(
+        bool aCheckForFallback = true) const;
+  };
+  std::unordered_map<int64_t, TextureInfo> mTextureInfo;
+  nsRefPtrHashtable<nsPtrHashKey<void>, gfx::DataSourceSurface> mDataSurfaces;
+  gfx::ReferencePtr mMappedSurface;
+  UniquePtr<gfx::DataSourceSurface::ScopedMap> mPreparedMap;
+  Atomic<bool> mDeactivated{false};
+  Atomic<bool> mBlocked{false};
+  Atomic<bool> mIPDLClosed{false};
+  bool mIsInTransaction = false;
+  bool mDeviceResetInProgress = false;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CanvasTranslator_h
diff --git a/gfx/layers/ipc/CompositableForwarder.cpp b/gfx/layers/ipc/CompositableForwarder.cpp
new file mode 100644
index 0000000000..369dff086a
--- /dev/null
+++ b/gfx/layers/ipc/CompositableForwarder.cpp
@@ -0,0 +1,15 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CompositableForwarder.h"
+
+#include "mozilla/layers/CompositableClient.h"
+#include "mozilla/layers/TextureClient.h"
+
+namespace mozilla::layers {
+CompositableForwarder::CompositableForwarder() = default;
+CompositableForwarder::~CompositableForwarder() = default;
+}  // namespace mozilla::layers
diff --git a/gfx/layers/ipc/CompositableForwarder.h b/gfx/layers/ipc/CompositableForwarder.h
new file mode 100644
index 0000000000..ba4bb41b5d
--- /dev/null
+++ b/gfx/layers/ipc/CompositableForwarder.h
@@ -0,0 +1,193 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_COMPOSITABLEFORWARDER
+#define MOZILLA_LAYERS_COMPOSITABLEFORWARDER
+
+#include <stdint.h>  // for int32_t, uint32_t, uint64_t
+#include "mozilla/Assertions.h"  // for AssertionConditionType, MOZ_ASSERT, MOZ_ASSERT_HELPER1
+#include "mozilla/Atomics.h"
+#include "mozilla/RefPtr.h"             // for RefPtr
+#include "mozilla/TimeStamp.h"          // for TimeStamp
+#include "mozilla/ipc/ProtocolUtils.h"  // for IToplevelProtocol, ProtocolID
+#include "mozilla/layers/KnowsCompositor.h"  // for KnowsCompositor
+#include "nsRect.h"                          // for nsIntRect
+#include "nsRegion.h"                        // for nsIntRegion
+#include "nsTArray.h"                        // for nsTArray
+
+namespace mozilla {
+namespace layers {
+class CompositableClient;
+class CompositableHandle;
+class ImageContainer;
+class PTextureChild;
+class SurfaceDescriptorTiles;
+class TextureClient;
+
+/**
+ * FwdTransactionCounter issues forwarder transaction numbers that represent a
+ * sequential stream of transactions to be transported over IPDL. Since every
+ * top-level protocol represents its own independently-sequenced IPDL queue,
+ * transaction numbers most naturally align with top-level protocols, rather
+ * than have different sub-protocols with their own independent transaction
+ * numbers that can't be usefully sequenced. FwdTransactionCounter expects
+ * users of it to provide themselves as proof they are a top-level protocol
+ * to avoid issues.
+ */
+struct FwdTransactionCounter {
+  explicit FwdTransactionCounter(mozilla::ipc::IToplevelProtocol* aToplevel)
+      : mFwdTransactionType(aToplevel->GetProtocolId()) {}
+
+  /**
+   * The ID of the top-level protocol. This is useful to tag the source of
+   * the transaction numbers in case different sources must be disambiguated.
+   */
+  mozilla::ipc::ProtocolId mFwdTransactionType;
+
+  /**
+   * Transaction id of ShadowLayerForwarder.
+   * It is incremented by UpdateFwdTransactionId() in each BeginTransaction()
+   * call.
+   */
+  uint64_t mFwdTransactionId = 0;
+};
+
+/**
+ * FwdTransactionTracker is to be used by CompositableForwarder consumers that
+ * must remember the last transaction in which they were used.
+ */
+class FwdTransactionTracker {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(FwdTransactionTracker)
+
+  static already_AddRefed<FwdTransactionTracker> GetOrCreate(
+      RefPtr<FwdTransactionTracker>& aTracker) {
+    if (!aTracker) {
+      aTracker = new FwdTransactionTracker;
+    }
+    return do_AddRef(aTracker);
+  }
+
+  bool IsUsed() const { return mFwdTransactionType && mFwdTransactionId; }
+
+  void Use(const FwdTransactionCounter& aCounter) {
+    mFwdTransactionType = aCounter.mFwdTransactionType;
+    mFwdTransactionId = aCounter.mFwdTransactionId;
+  }
+
+  Atomic<mozilla::ipc::ProtocolId> mFwdTransactionType{
+      (mozilla::ipc::ProtocolId)0};
+  Atomic<uint64_t> mFwdTransactionId{0};
+
+ private:
+  FwdTransactionTracker() = default;
+  ~FwdTransactionTracker() = default;
+};
+
+inline RemoteTextureTxnType ToRemoteTextureTxnType(
+    const RefPtr<FwdTransactionTracker>& aTracker) {
+  return aTracker ? (RemoteTextureTxnType)aTracker->mFwdTransactionType : 0;
+}
+
+inline RemoteTextureTxnId ToRemoteTextureTxnId(
+    const RefPtr<FwdTransactionTracker>& aTracker) {
+  return aTracker ? (RemoteTextureTxnId)aTracker->mFwdTransactionId : 0;
+}
+
+/**
+ * A transaction is a set of changes that happenned on the content side, that
+ * should be sent to the compositor side.
+ * CompositableForwarder is an interface to manage a transaction of
+ * compositable objetcs.
+ *
+ * ShadowLayerForwarder is an example of a CompositableForwarder (that can
+ * additionally forward modifications of the Layer tree).
+ * ImageBridgeChild is another CompositableForwarder.
+ *
+ * CompositableForwarder implements KnowsCompositor for simplicity as all
+ * implementations of CompositableForwarder currently also implement
+ * KnowsCompositor. This dependency could be split if we add new use cases.
+ */
+class CompositableForwarder : public KnowsCompositor {
+ public:
+  CompositableForwarder();
+  ~CompositableForwarder();
+
+  /**
+   * Setup the IPDL actor for aCompositable to be part of layers
+   * transactions.
+   */
+  virtual void Connect(CompositableClient* aCompositable,
+                       ImageContainer* aImageContainer = nullptr) = 0;
+
+  virtual void ReleaseCompositable(const CompositableHandle& aHandle) = 0;
+  virtual bool DestroyInTransaction(PTextureChild* aTexture) = 0;
+
+  /**
+   * Tell the CompositableHost on the compositor side to remove the texture
+   * from the CompositableHost.
+   * This function does not delete the TextureHost corresponding to the
+   * TextureClient passed in parameter.
+   * When the TextureClient has TEXTURE_DEALLOCATE_CLIENT flag,
+   * the transaction becomes synchronous.
+   */
+  virtual void RemoveTextureFromCompositable(CompositableClient* aCompositable,
+                                             TextureClient* aTexture) = 0;
+
+  struct TimedTextureClient {
+    TimedTextureClient()
+        : mTextureClient(nullptr), mFrameID(0), mProducerID(0) {}
+
+    TextureClient* mTextureClient;
+    TimeStamp mTimeStamp;
+    nsIntRect mPictureRect;
+    int32_t mFrameID;
+    int32_t mProducerID;
+  };
+  /**
+   * Tell the CompositableHost on the compositor side what textures to use for
+   * the next composition.
+   */
+  virtual void UseTextures(CompositableClient* aCompositable,
+                           const nsTArray<TimedTextureClient>& aTextures) = 0;
+
+  virtual void UseRemoteTexture(
+      CompositableClient* aCompositable, const RemoteTextureId aTextureId,
+      const RemoteTextureOwnerId aOwnerId, const gfx::IntSize aSize,
+      const TextureFlags aFlags,
+      const RefPtr<layers::FwdTransactionTracker>& aTracker) = 0;
+
+  void UpdateFwdTransactionId() {
+    ++GetFwdTransactionCounter().mFwdTransactionId;
+  }
+  uint64_t GetFwdTransactionId() {
+    return GetFwdTransactionCounter().mFwdTransactionId;
+  }
+  mozilla::ipc::ProtocolId GetFwdTransactionType() {
+    return GetFwdTransactionCounter().mFwdTransactionType;
+  }
+
+  virtual bool InForwarderThread() = 0;
+
+  void AssertInForwarderThread() { MOZ_ASSERT(InForwarderThread()); }
+
+ protected:
+  virtual FwdTransactionCounter& GetFwdTransactionCounter() = 0;
+
+  void TrackFwdTransaction(const RefPtr<FwdTransactionTracker>& aTracker) {
+    if (aTracker) {
+      aTracker->Use(GetFwdTransactionCounter());
+    }
+  }
+
+  nsTArray<RefPtr<TextureClient>> mTexturesToRemove;
+  nsTArray<RefPtr<CompositableClient>> mCompositableClientsToRemove;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositableTransactionParent.cpp b/gfx/layers/ipc/CompositableTransactionParent.cpp
new file mode 100644
index 0000000000..bb6c5a209b
--- /dev/null
+++ b/gfx/layers/ipc/CompositableTransactionParent.cpp
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CompositableTransactionParent.h"
+#include "CompositableHost.h"        // for CompositableParent, etc
+#include "CompositorBridgeParent.h"  // for CompositorBridgeParent
+#include "mozilla/Assertions.h"      // for MOZ_ASSERT, etc
+#include "mozilla/RefPtr.h"          // for RefPtr
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/ImageBridgeParent.h"  // for ImageBridgeParent
+#include "mozilla/layers/LayersSurfaces.h"     // for SurfaceDescriptor
+#include "mozilla/layers/LayersTypes.h"        // for MOZ_LAYERS_LOG
+#include "mozilla/layers/TextureHost.h"        // for TextureHost
+#include "mozilla/layers/WebRenderImageHost.h"
+#include "mozilla/mozalloc.h"  // for operator delete
+#include "mozilla/Unused.h"
+#include "nsDebug.h"   // for NS_WARNING, NS_ASSERTION
+#include "nsRegion.h"  // for nsIntRegion
+
+namespace mozilla {
+namespace layers {
+
+bool CompositableParentManager::ReceiveCompositableUpdate(
+    const CompositableOperation& aEdit) {
+  // Ignore all operations on compositables created on stale compositors. We
+  // return true because the child is unable to handle errors.
+  RefPtr<CompositableHost> compositable =
+      FindCompositable(aEdit.compositable());
+  if (!compositable) {
+    return false;
+  }
+  return ReceiveCompositableUpdate(aEdit.detail(), WrapNotNull(compositable),
+                                   aEdit.compositable());
+}
+
+bool CompositableParentManager::ReceiveCompositableUpdate(
+    const CompositableOperationDetail& aDetail,
+    NotNull<CompositableHost*> aCompositable,
+    const CompositableHandle& aHandle) {
+  switch (aDetail.type()) {
+    case CompositableOperationDetail::TOpRemoveTexture: {
+      const OpRemoveTexture& op = aDetail.get_OpRemoveTexture();
+
+      RefPtr<TextureHost> tex =
+          TextureHost::AsTextureHost(op.texture().AsParent());
+
+      MOZ_ASSERT(tex.get());
+      aCompositable->RemoveTextureHost(tex);
+      break;
+    }
+    case CompositableOperationDetail::TOpUseTexture: {
+      const OpUseTexture& op = aDetail.get_OpUseTexture();
+
+      AutoTArray<CompositableHost::TimedTexture, 4> textures;
+      for (auto& timedTexture : op.textures()) {
+        CompositableHost::TimedTexture* t = textures.AppendElement();
+        t->mTexture =
+            TextureHost::AsTextureHost(timedTexture.texture().AsParent());
+        MOZ_ASSERT(t->mTexture);
+        t->mTimeStamp = timedTexture.timeStamp();
+        t->mPictureRect = timedTexture.picture();
+        t->mFrameID = timedTexture.frameID();
+        t->mProducerID = timedTexture.producerID();
+        if (timedTexture.readLocked()) {
+          t->mTexture->SetReadLocked();
+        }
+      }
+      if (textures.Length() > 0) {
+        aCompositable->UseTextureHost(textures);
+
+        for (auto& timedTexture : op.textures()) {
+          RefPtr<TextureHost> texture =
+              TextureHost::AsTextureHost(timedTexture.texture().AsParent());
+          if (texture) {
+            texture->SetLastFwdTransactionId(mFwdTransactionId);
+            // Make sure that each texture was handled by the compositable
+            // because the recycling logic depends on it.
+            MOZ_ASSERT(texture->NumCompositableRefs() > 0);
+          }
+        }
+      }
+      break;
+    }
+    case CompositableOperationDetail::TOpUseRemoteTexture: {
+      const OpUseRemoteTexture& op = aDetail.get_OpUseRemoteTexture();
+      auto* host = aCompositable->AsWebRenderImageHost();
+      MOZ_ASSERT(host);
+
+      host->PushPendingRemoteTexture(op.textureId(), op.ownerId(),
+                                     GetChildProcessId(), op.size(),
+                                     op.textureFlags());
+      host->UseRemoteTexture();
+      break;
+    }
+    default: {
+      MOZ_ASSERT(false, "bad type");
+    }
+  }
+
+  return true;
+}
+
+void CompositableParentManager::DestroyActor(const OpDestroy& aOp) {
+  switch (aOp.type()) {
+    case OpDestroy::TPTexture: {
+      auto actor = aOp.get_PTexture().AsParent();
+      TextureHost::ReceivedDestroy(actor);
+      break;
+    }
+    case OpDestroy::TCompositableHandle: {
+      ReleaseCompositable(aOp.get_CompositableHandle());
+      break;
+    }
+    default: {
+      MOZ_ASSERT(false, "unsupported type");
+    }
+  }
+}
+
+RefPtr<CompositableHost> CompositableParentManager::AddCompositable(
+    const CompositableHandle& aHandle, const TextureInfo& aInfo) {
+  if (mCompositables.find(aHandle.Value()) != mCompositables.end()) {
+    NS_ERROR("Client should not allocate duplicate handles");
+    return nullptr;
+  }
+  if (!aHandle) {
+    NS_ERROR("Client should not allocate 0 as a handle");
+    return nullptr;
+  }
+
+  RefPtr<CompositableHost> host = CompositableHost::Create(aInfo);
+  if (!host) {
+    return nullptr;
+  }
+
+  mCompositables[aHandle.Value()] = host;
+  return host;
+}
+
+RefPtr<CompositableHost> CompositableParentManager::FindCompositable(
+    const CompositableHandle& aHandle) {
+  auto iter = mCompositables.find(aHandle.Value());
+  if (iter == mCompositables.end()) {
+    return nullptr;
+  }
+
+  return iter->second;
+}
+
+void CompositableParentManager::ReleaseCompositable(
+    const CompositableHandle& aHandle) {
+  auto iter = mCompositables.find(aHandle.Value());
+  if (iter == mCompositables.end()) {
+    return;
+  }
+  iter->second->OnReleased();
+  mCompositables.erase(iter);
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositableTransactionParent.h b/gfx/layers/ipc/CompositableTransactionParent.h
new file mode 100644
index 0000000000..172c6bb035
--- /dev/null
+++ b/gfx/layers/ipc/CompositableTransactionParent.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_COMPOSITABLETRANSACTIONPARENT_H
+#define MOZILLA_LAYERS_COMPOSITABLETRANSACTIONPARENT_H
+
+#include <vector>                // for vector
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/NotNull.h"
+#include "mozilla/layers/ISurfaceAllocator.h"  // for ISurfaceAllocator
+#include "mozilla/layers/LayersMessages.h"     // for EditReply, etc
+#include "mozilla/layers/TextureClient.h"
+#include "CompositableHost.h"
+
+namespace mozilla {
+namespace layers {
+
+// Since PCompositble has two potential manager protocols, we can't just call
+// the Manager() method usually generated when there's one manager protocol,
+// so both manager protocols implement this and we keep a reference to them
+// through this interface.
+class CompositableParentManager : public HostIPCAllocator {
+ public:
+  CompositableParentManager() = default;
+
+  void DestroyActor(const OpDestroy& aOp);
+
+  void UpdateFwdTransactionId(uint64_t aTransactionId) {
+    MOZ_ASSERT(mFwdTransactionId < aTransactionId);
+    mFwdTransactionId = aTransactionId;
+  }
+
+  uint64_t GetFwdTransactionId() { return mFwdTransactionId; }
+
+  RefPtr<CompositableHost> AddCompositable(const CompositableHandle& aHandle,
+                                           const TextureInfo& aInfo);
+  RefPtr<CompositableHost> FindCompositable(const CompositableHandle& aHandle);
+
+ protected:
+  /**
+   * Handle the IPDL messages that affect PCompositable actors.
+   */
+  bool ReceiveCompositableUpdate(const CompositableOperation& aEdit);
+  bool ReceiveCompositableUpdate(const CompositableOperationDetail& aDetail,
+                                 NotNull<CompositableHost*> aCompositable,
+                                 const CompositableHandle& aHandle);
+
+  void ReleaseCompositable(const CompositableHandle& aHandle);
+
+  uint64_t mFwdTransactionId = 0;
+
+  /**
+   * Mapping form IDs to CompositableHosts.
+   */
+  std::map<uint64_t, RefPtr<CompositableHost>> mCompositables;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositorBench.cpp b/gfx/layers/ipc/CompositorBench.cpp
new file mode 100644
index 0000000000..0fb4d8012b
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBench.cpp
@@ -0,0 +1,352 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "CompositorBench.h"
+
+#ifdef MOZ_COMPOSITOR_BENCH
+#  include "mozilla/gfx/2D.h"
+#  include "mozilla/layers/Compositor.h"
+#  include "mozilla/layers/Effects.h"
+#  include "mozilla/ProfilerMarkers.h"
+#  include "mozilla/StaticPrefs_layers.h"
+#  include "mozilla/TimeStamp.h"
+#  include <math.h>
+
+#  define TEST_STEPS 1000
+#  define DURATION_THRESHOLD 30
+#  define THRESHOLD_ABORT_COUNT 5
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::gfx;
+
+static float SimplePseudoRandom(int aStep, int aCount) {
+  srand(aStep * 1000 + aCount);
+  return static_cast<float>(rand()) / static_cast<float>(RAND_MAX);
+}
+
+class BenchTest {
+ public:
+  BenchTest(const char* aTestName) : mTestName(aTestName) {}
+
+  virtual ~BenchTest() = default;
+
+  virtual void Setup(Compositor* aCompositor, size_t aStep) {}
+  virtual void Teardown(Compositor* aCompositor) {}
+  virtual void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                         size_t aStep) = 0;
+
+  const char* ToString() { return mTestName; }
+
+ private:
+  const char* mTestName;
+};
+
+static void DrawFrameTrivialQuad(Compositor* aCompositor,
+                                 const gfx::Rect& aScreenRect, size_t aStep,
+                                 const EffectChain& effects) {
+  for (size_t i = 0; i < aStep * 10; i++) {
+    const gfx::Rect& rect = gfx::Rect(i % (int)aScreenRect.width,
+                                      (int)(i / aScreenRect.height), 1, 1);
+    const gfx::Rect& clipRect = aScreenRect;
+
+    float opacity = 1.f;
+
+    gfx::Matrix transform2d;
+
+    gfx::Matrix4x4 transform = gfx::Matrix4x4::From2D(transform2d);
+
+    aCompositor->DrawQuad(rect, clipRect, effects, opacity, transform);
+  }
+}
+
+static void DrawFrameStressQuad(Compositor* aCompositor,
+                                const gfx::Rect& aScreenRect, size_t aStep,
+                                const EffectChain& effects) {
+  for (size_t i = 0; i < aStep * 10; i++) {
+    const gfx::Rect& rect =
+        gfx::Rect(aScreenRect.width * SimplePseudoRandom(i, 0),
+                  aScreenRect.height * SimplePseudoRandom(i, 1),
+                  aScreenRect.width * SimplePseudoRandom(i, 2),
+                  aScreenRect.height * SimplePseudoRandom(i, 3));
+    const gfx::Rect& clipRect = aScreenRect;
+
+    float opacity = 1.f;
+
+    gfx::Matrix transform2d;
+    transform2d = transform2d.PreRotate(SimplePseudoRandom(i, 4) * 70.f);
+
+    gfx::Matrix4x4 transform = gfx::Matrix4x4::From2D(transform2d);
+
+    aCompositor->DrawQuad(rect, clipRect, effects, opacity, transform);
+  }
+}
+
+class EffectSolidColorBench : public BenchTest {
+ public:
+  EffectSolidColorBench()
+      : BenchTest("EffectSolidColorBench (clear frame with EffectSolidColor)") {
+  }
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    float tmp;
+    float red = modff(aStep * 0.03f, &tmp);
+    EffectChain effects;
+    effects.mPrimaryEffect =
+        new EffectSolidColor(gfx::DeviceColor(red, 0.4f, 0.4f, 1.0f));
+
+    const gfx::Rect& rect = aScreenRect;
+    const gfx::Rect& clipRect = aScreenRect;
+
+    float opacity = 1.f;
+
+    gfx::Matrix4x4 transform;
+    aCompositor->DrawQuad(rect, clipRect, effects, opacity, transform);
+  }
+};
+
+class EffectSolidColorTrivialBench : public BenchTest {
+ public:
+  EffectSolidColorTrivialBench()
+      : BenchTest("EffectSolidColorTrivialBench (10s 1x1 EffectSolidColor)") {}
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    EffectChain effects;
+    effects.mPrimaryEffect = CreateEffect(aStep);
+
+    DrawFrameTrivialQuad(aCompositor, aScreenRect, aStep, effects);
+  }
+
+  already_AddRefed<Effect> CreateEffect(size_t i) {
+    float tmp;
+    float red = modff(i * 0.03f, &tmp);
+    EffectChain effects;
+    return MakeAndAddRef<EffectSolidColor>(
+        gfx::DeviceColor(red, 0.4f, 0.4f, 1.0f));
+  }
+};
+
+class EffectSolidColorStressBench : public BenchTest {
+ public:
+  EffectSolidColorStressBench()
+      : BenchTest(
+            "EffectSolidColorStressBench (10s various EffectSolidColor)") {}
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    EffectChain effects;
+    effects.mPrimaryEffect = CreateEffect(aStep);
+
+    DrawFrameStressQuad(aCompositor, aScreenRect, aStep, effects);
+  }
+
+  already_AddRefed<Effect> CreateEffect(size_t i) {
+    float tmp;
+    float red = modff(i * 0.03f, &tmp);
+    EffectChain effects;
+    return MakeAndAddRef<EffectSolidColor>(
+        gfx::DeviceColor(red, 0.4f, 0.4f, 1.0f));
+  }
+};
+
+class UploadBench : public BenchTest {
+ public:
+  UploadBench() : BenchTest("Upload Bench (10s 256x256 upload)") {}
+
+  uint32_t* mBuf;
+  RefPtr<DataSourceSurface> mSurface;
+  RefPtr<DataTextureSource> mTexture;
+
+  virtual void Setup(Compositor* aCompositor, size_t aStep) {
+    int bytesPerPixel = 4;
+    int w = 256;
+    int h = 256;
+    mBuf = (uint32_t*)malloc(w * h * sizeof(uint32_t));
+
+    mSurface = Factory::CreateWrappingDataSourceSurface(
+        reinterpret_cast<uint8_t*>(mBuf), w * bytesPerPixel, IntSize(w, h),
+        SurfaceFormat::B8G8R8A8);
+    mTexture = aCompositor->CreateDataTextureSource();
+  }
+
+  virtual void Teardown(Compositor* aCompositor) {
+    mSurface = nullptr;
+    mTexture = nullptr;
+    free(mBuf);
+  }
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    for (size_t i = 0; i < aStep * 10; i++) {
+      mTexture->Update(mSurface);
+    }
+  }
+};
+
+class TrivialTexturedQuadBench : public BenchTest {
+ public:
+  TrivialTexturedQuadBench()
+      : BenchTest("Trvial Textured Quad (10s 256x256 quads)") {}
+
+  uint32_t* mBuf;
+  RefPtr<DataSourceSurface> mSurface;
+  RefPtr<DataTextureSource> mTexture;
+
+  virtual void Setup(Compositor* aCompositor, size_t aStep) {
+    int bytesPerPixel = 4;
+    size_t w = 256;
+    size_t h = 256;
+    mBuf = (uint32_t*)malloc(w * h * sizeof(uint32_t));
+    for (size_t i = 0; i < w * h; i++) {
+      mBuf[i] = 0xFF00008F;
+    }
+
+    mSurface = Factory::CreateWrappingDataSourceSurface(
+        reinterpret_cast<uint8_t*>(mBuf), w * bytesPerPixel, IntSize(w, h),
+        SurfaceFormat::B8G8R8A8);
+    mTexture = aCompositor->CreateDataTextureSource();
+    mTexture->Update(mSurface);
+  }
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    EffectChain effects;
+    effects.mPrimaryEffect = CreateEffect(aStep);
+
+    DrawFrameTrivialQuad(aCompositor, aScreenRect, aStep, effects);
+  }
+
+  virtual void Teardown(Compositor* aCompositor) {
+    mSurface = nullptr;
+    mTexture = nullptr;
+    free(mBuf);
+  }
+
+  already_AddRefed<Effect> CreateEffect(size_t i) {
+    return CreateTexturedEffect(SurfaceFormat::B8G8R8A8, mTexture,
+                                SamplingFilter::POINT, true);
+  }
+};
+
+class StressTexturedQuadBench : public BenchTest {
+ public:
+  StressTexturedQuadBench()
+      : BenchTest("Stress Textured Quad (10s 256x256 quads)") {}
+
+  uint32_t* mBuf;
+  RefPtr<DataSourceSurface> mSurface;
+  RefPtr<DataTextureSource> mTexture;
+
+  virtual void Setup(Compositor* aCompositor, size_t aStep) {
+    int bytesPerPixel = 4;
+    size_t w = 256;
+    size_t h = 256;
+    mBuf = (uint32_t*)malloc(w * h * sizeof(uint32_t));
+    for (size_t i = 0; i < w * h; i++) {
+      mBuf[i] = 0xFF00008F;
+    }
+
+    mSurface = Factory::CreateWrappingDataSourceSurface(
+        reinterpret_cast<uint8_t*>(mBuf), w * bytesPerPixel, IntSize(w, h),
+        SurfaceFormat::B8G8R8A8);
+    mTexture = aCompositor->CreateDataTextureSource();
+    mTexture->Update(mSurface);
+  }
+
+  void DrawFrame(Compositor* aCompositor, const gfx::Rect& aScreenRect,
+                 size_t aStep) {
+    EffectChain effects;
+    effects.mPrimaryEffect = CreateEffect(aStep);
+
+    DrawFrameStressQuad(aCompositor, aScreenRect, aStep, effects);
+  }
+
+  virtual void Teardown(Compositor* aCompositor) {
+    mSurface = nullptr;
+    mTexture = nullptr;
+    free(mBuf);
+  }
+
+  virtual already_AddRefed<Effect> CreateEffect(size_t i) {
+    return CreateTexturedEffect(SurfaceFormat::B8G8R8A8, mTexture,
+                                SamplingFilter::POINT, true);
+  }
+};
+
+static void RunCompositorBench(Compositor* aCompositor,
+                               const gfx::Rect& aScreenRect) {
+  std::vector<BenchTest*> tests;
+
+  tests.push_back(new EffectSolidColorBench());
+  tests.push_back(new UploadBench());
+  tests.push_back(new EffectSolidColorTrivialBench());
+  tests.push_back(new EffectSolidColorStressBench());
+  tests.push_back(new TrivialTexturedQuadBench());
+  tests.push_back(new StressTexturedQuadBench());
+
+  for (size_t i = 0; i < tests.size(); i++) {
+    BenchTest* test = tests[i];
+    std::vector<TimeDuration> results;
+    int testsOverThreshold = 0;
+    PROFILER_MARKER_UNTYPED(
+        ProfilerString8View::WrapNullTerminatedString(test->ToString()),
+        GRAPHICS);
+    for (size_t j = 0; j < TEST_STEPS; j++) {
+      test->Setup(aCompositor, j);
+
+      TimeStamp start = TimeStamp::Now();
+      IntRect screenRect(aScreenRect.x, aScreenRect.y, aScreenRect.width,
+                         aScreenRect.height);
+      aCompositor->BeginFrame(IntRect(screenRect.x, screenRect.y,
+                                      screenRect.width, screenRect.height),
+                              nullptr, aScreenRect, nullptr, nullptr);
+
+      test->DrawFrame(aCompositor, aScreenRect, j);
+
+      aCompositor->EndFrame();
+      results.push_back(TimeStamp::Now() - start);
+
+      if (results[j].ToMilliseconds() > DURATION_THRESHOLD) {
+        testsOverThreshold++;
+        if (testsOverThreshold == THRESHOLD_ABORT_COUNT) {
+          test->Teardown(aCompositor);
+          break;
+        }
+      } else {
+        testsOverThreshold = 0;
+      }
+      test->Teardown(aCompositor);
+    }
+
+    printf_stderr("%s\n", test->ToString());
+    printf_stderr("Run step, Time (ms)\n");
+    for (size_t j = 0; j < results.size(); j++) {
+      printf_stderr("%i,%f\n", j, (float)results[j].ToMilliseconds());
+    }
+    printf_stderr("\n", test->ToString());
+  }
+
+  for (size_t i = 0; i < tests.size(); i++) {
+    delete tests[i];
+  }
+}
+
+void CompositorBench(Compositor* aCompositor, const gfx::IntRect& aScreenRect) {
+  static bool sRanBenchmark = false;
+  bool wantBenchmark = StaticPrefs::layers_bench_enabled();
+  if (wantBenchmark && !sRanBenchmark) {
+    RunCompositorBench(aCompositor, aScreenRect);
+  }
+  sRanBenchmark = wantBenchmark;
+}
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositorBench.h b/gfx/layers/ipc/CompositorBench.h
new file mode 100644
index 0000000000..4a3c5874e9
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBench.h
@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorBench_h
+#define mozilla_layers_CompositorBench_h
+
+#include "mozilla/gfx/Rect.h"  // for Rect
+
+namespace mozilla {
+namespace layers {
+
+class Compositor;
+
+// Uncomment this line to rebuild with compositor bench.
+// #define MOZ_COMPOSITOR_BENCH
+
+#ifdef MOZ_COMPOSITOR_BENCH
+void CompositorBench(Compositor* aCompositor, const gfx::IntRect& aScreenRect);
+#else
+static inline void CompositorBench(Compositor* aCompositor,
+                                   const gfx::IntRect& aScreenRect) {}
+#endif
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositorBridgeChild.cpp b/gfx/layers/ipc/CompositorBridgeChild.cpp
new file mode 100644
index 0000000000..070e6d673e
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBridgeChild.cpp
@@ -0,0 +1,640 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include <stddef.h>     // for size_t
+#include "base/task.h"  // for NewRunnableMethod, etc
+#include "mozilla/StaticPrefs_layers.h"
+#include "mozilla/layers/CompositorManagerChild.h"
+#include "mozilla/layers/ImageBridgeChild.h"
+#include "mozilla/layers/APZChild.h"
+#include "mozilla/layers/IAPZCTreeManager.h"
+#include "mozilla/layers/APZCTreeManagerChild.h"
+#include "mozilla/layers/CanvasChild.h"
+#include "mozilla/layers/WebRenderLayerManager.h"
+#include "mozilla/layers/PTextureChild.h"
+#include "mozilla/layers/TextureClient.h"      // for TextureClient
+#include "mozilla/layers/TextureClientPool.h"  // for TextureClientPool
+#include "mozilla/layers/WebRenderBridgeChild.h"
+#include "mozilla/layers/SyncObject.h"  // for SyncObjectClient
+#include "mozilla/gfx/CanvasManagerChild.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "mozilla/Telemetry.h"
+#include "gfxConfig.h"
+#include "nsDebug.h"          // for NS_WARNING
+#include "nsISupportsImpl.h"  // for MOZ_COUNT_CTOR, etc
+#include "nsTArray.h"         // for nsTArray, nsTArray_Impl
+#include "mozilla/dom/BrowserChild.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/Unused.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "nsThreadUtils.h"
+#if defined(XP_WIN)
+#  include "WinUtils.h"
+#endif
+#include "mozilla/widget/CompositorWidget.h"
+#ifdef MOZ_WIDGET_SUPPORTS_OOP_COMPOSITING
+#  include "mozilla/widget/CompositorWidgetChild.h"
+#endif
+#include "VsyncSource.h"
+
+using mozilla::Unused;
+using mozilla::gfx::GPUProcessManager;
+
+namespace mozilla {
+namespace layers {
+
+static int sShmemCreationCounter = 0;
+
+static void ResetShmemCounter() { sShmemCreationCounter = 0; }
+
+static void ShmemAllocated(CompositorBridgeChild* aProtocol) {
+  sShmemCreationCounter++;
+  if (sShmemCreationCounter > 256) {
+    aProtocol->SendSyncWithCompositor();
+    ResetShmemCounter();
+    MOZ_PERFORMANCE_WARNING(
+        "gfx", "The number of shmem allocations is too damn high!");
+  }
+}
+
+static StaticRefPtr<CompositorBridgeChild> sCompositorBridge;
+
+Atomic<int32_t> KnowsCompositor::sSerialCounter(0);
+
+CompositorBridgeChild::CompositorBridgeChild(CompositorManagerChild* aManager)
+    : mCompositorManager(aManager),
+      mIdNamespace(0),
+      mResourceId(0),
+      mCanSend(false),
+      mActorDestroyed(false),
+      mPaused(false),
+      mThread(NS_GetCurrentThread()),
+      mProcessToken(0),
+      mSectionAllocator(nullptr) {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+CompositorBridgeChild::~CompositorBridgeChild() {
+  if (mCanSend) {
+    gfxCriticalError() << "CompositorBridgeChild was not deinitialized";
+  }
+}
+
+bool CompositorBridgeChild::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void CompositorBridgeChild::PrepareFinalDestroy() {
+  // Because of medium high priority DidComposite, we need to repost to
+  // medium high priority queue to ensure the actor is destroyed after possible
+  // pending DidComposite message.
+  nsCOMPtr<nsIRunnable> runnable =
+      NewRunnableMethod("CompositorBridgeChild::AfterDestroy", this,
+                        &CompositorBridgeChild::AfterDestroy);
+  NS_DispatchToCurrentThreadQueue(runnable.forget(),
+                                  EventQueuePriority::MediumHigh);
+}
+
+void CompositorBridgeChild::AfterDestroy() {
+  // Note that we cannot rely upon mCanSend here because we already set that to
+  // false to prevent normal IPDL calls from being made after SendWillClose.
+  // The only time we should not issue Send__delete__ is if the actor is already
+  // destroyed, e.g. the compositor process crashed.
+  if (!mActorDestroyed) {
+    // We saw this send fail quite often with "Channel closing", probably a race
+    // with the other side closing or some event scheduling order.
+    if (GetIPCChannel()->CanSend()) {
+      Send__delete__(this);
+    }
+    mActorDestroyed = true;
+  }
+
+  if (sCompositorBridge == this) {
+    sCompositorBridge = nullptr;
+  }
+}
+
+void CompositorBridgeChild::Destroy() {
+  // This must not be called from the destructor!
+  mTexturesWaitingNotifyNotUsed.clear();
+
+  // Destroying the layer manager may cause all sorts of things to happen, so
+  // let's make sure there is still a reference to keep this alive whatever
+  // happens.
+  RefPtr<CompositorBridgeChild> selfRef = this;
+
+  for (size_t i = 0; i < mTexturePools.Length(); i++) {
+    mTexturePools[i]->Destroy();
+  }
+
+  if (mSectionAllocator) {
+    delete mSectionAllocator;
+    mSectionAllocator = nullptr;
+  }
+
+  if (mLayerManager) {
+    mLayerManager->Destroy();
+    mLayerManager = nullptr;
+  }
+
+  if (!mCanSend) {
+    // We may have already called destroy but still have lingering references
+    // or CompositorBridgeChild::ActorDestroy was called. Ensure that we do our
+    // post destroy clean up no matter what. It is safe to call multiple times.
+    NS_GetCurrentThread()->Dispatch(
+        NewRunnableMethod("CompositorBridgeChild::PrepareFinalDestroy", selfRef,
+                          &CompositorBridgeChild::PrepareFinalDestroy));
+    return;
+  }
+
+  AutoTArray<PWebRenderBridgeChild*, 16> wrBridges;
+  ManagedPWebRenderBridgeChild(wrBridges);
+  for (int i = wrBridges.Length() - 1; i >= 0; --i) {
+    RefPtr<WebRenderBridgeChild> wrBridge =
+        static_cast<WebRenderBridgeChild*>(wrBridges[i]);
+    wrBridge->Destroy(/* aIsSync */ false);
+  }
+
+  AutoTArray<PAPZChild*, 16> apzChildren;
+  ManagedPAPZChild(apzChildren);
+  for (PAPZChild* child : apzChildren) {
+    Unused << child->SendDestroy();
+  }
+
+  const ManagedContainer<PTextureChild>& textures = ManagedPTextureChild();
+  for (const auto& key : textures) {
+    RefPtr<TextureClient> texture = TextureClient::AsTextureClient(key);
+
+    if (texture) {
+      texture->Destroy();
+    }
+  }
+
+  // The WillClose message is synchronous, so we know that after it returns
+  // any messages sent by the above code will have been processed on the
+  // other side.
+  SendWillClose();
+  mCanSend = false;
+
+  // We no longer care about unexpected shutdowns, in the remote process case.
+  mProcessToken = 0;
+
+  // The call just made to SendWillClose can result in IPC from the
+  // CompositorBridgeParent to the CompositorBridgeChild (e.g. caused by the
+  // destruction of shared memory). We need to ensure this gets processed by the
+  // CompositorBridgeChild before it gets destroyed. It suffices to ensure that
+  // events already in the thread get processed before the
+  // CompositorBridgeChild is destroyed, so we add a task to the thread to
+  // handle compositor destruction.
+
+  // From now on we can't send any message message.
+  NS_GetCurrentThread()->Dispatch(
+      NewRunnableMethod("CompositorBridgeChild::PrepareFinalDestroy", selfRef,
+                        &CompositorBridgeChild::PrepareFinalDestroy));
+}
+
+// static
+void CompositorBridgeChild::ShutDown() {
+  if (sCompositorBridge) {
+    sCompositorBridge->Destroy();
+    SpinEventLoopUntil("CompositorBridgeChild::ShutDown"_ns,
+                       [&]() { return !sCompositorBridge; });
+  }
+}
+
+void CompositorBridgeChild::InitForContent(uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aNamespace);
+
+  if (RefPtr<CompositorBridgeChild> old = sCompositorBridge.forget()) {
+    // Note that at this point, ActorDestroy may not have been called yet,
+    // meaning mCanSend is still true. In this case we will try to send a
+    // synchronous WillClose message to the parent, and will certainly get
+    // a false result and a MsgDropped processing error. This is okay.
+    old->Destroy();
+  }
+
+  mCanSend = true;
+  mIdNamespace = aNamespace;
+
+  sCompositorBridge = this;
+}
+
+void CompositorBridgeChild::InitForWidget(uint64_t aProcessToken,
+                                          WebRenderLayerManager* aLayerManager,
+                                          uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aProcessToken);
+  MOZ_ASSERT(aLayerManager);
+  MOZ_ASSERT(aNamespace);
+
+  mCanSend = true;
+  mProcessToken = aProcessToken;
+  mLayerManager = aLayerManager;
+  mIdNamespace = aNamespace;
+}
+
+/*static*/
+CompositorBridgeChild* CompositorBridgeChild::Get() {
+  // This is only expected to be used in child processes. While the parent
+  // process does have CompositorBridgeChild instances, it has _multiple_ (one
+  // per window), and therefore there is no global singleton available.
+  MOZ_ASSERT(!XRE_IsParentProcess());
+  return sCompositorBridge;
+}
+
+/* static */
+bool CompositorBridgeChild::CompositorIsInGPUProcess() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (XRE_IsParentProcess()) {
+    return !!GPUProcessManager::Get()->GetGPUChild();
+  }
+
+  MOZ_ASSERT(XRE_IsContentProcess());
+  CompositorBridgeChild* bridge = CompositorBridgeChild::Get();
+  if (!bridge) {
+    return false;
+  }
+
+  return bridge->OtherPid() != dom::ContentChild::GetSingleton()->OtherPid();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvDidComposite(
+    const LayersId& aId, const nsTArray<TransactionId>& aTransactionIds,
+    const TimeStamp& aCompositeStart, const TimeStamp& aCompositeEnd) {
+  // Hold a reference to keep texture pools alive.  See bug 1387799
+  const auto texturePools = mTexturePools.Clone();
+
+  for (const auto& id : aTransactionIds) {
+    if (mLayerManager) {
+      MOZ_ASSERT(!aId.IsValid());
+      MOZ_ASSERT(mLayerManager->GetBackendType() == LayersBackend::LAYERS_WR);
+      // Hold a reference to keep LayerManager alive. See Bug 1242668.
+      RefPtr<WebRenderLayerManager> m = mLayerManager;
+      m->DidComposite(id, aCompositeStart, aCompositeEnd);
+    } else if (aId.IsValid()) {
+      RefPtr<dom::BrowserChild> child = dom::BrowserChild::GetFrom(aId);
+      if (child) {
+        child->DidComposite(id, aCompositeStart, aCompositeEnd);
+      }
+    }
+  }
+
+  for (size_t i = 0; i < texturePools.Length(); i++) {
+    texturePools[i]->ReturnDeferredClients();
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvNotifyFrameStats(
+    nsTArray<FrameStats>&& aFrameStats) {
+  gfxPlatform::GetPlatform()->NotifyFrameStats(std::move(aFrameStats));
+  return IPC_OK();
+}
+
+void CompositorBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  if (aWhy == AbnormalShutdown) {
+    // If the parent side runs into a problem then the actor will be destroyed.
+    // There is nothing we can do in the child side, here sets mCanSend as
+    // false.
+    gfxCriticalNote << "CompositorBridgeChild receives IPC close with "
+                       "reason=AbnormalShutdown";
+  }
+
+  mCanSend = false;
+  mActorDestroyed = true;
+
+  if (mProcessToken && XRE_IsParentProcess()) {
+    GPUProcessManager::Get()->NotifyRemoteActorDestroyed(mProcessToken);
+  }
+}
+
+bool CompositorBridgeChild::SendWillClose() {
+  MOZ_RELEASE_ASSERT(mCanSend);
+  return PCompositorBridgeChild::SendWillClose();
+}
+
+bool CompositorBridgeChild::SendPause() {
+  if (!mCanSend) {
+    return false;
+  }
+  mPaused = true;
+  return PCompositorBridgeChild::SendPause();
+}
+
+bool CompositorBridgeChild::SendResume() {
+  if (!mCanSend) {
+    return false;
+  }
+  mPaused = false;
+  return PCompositorBridgeChild::SendResume();
+}
+
+bool CompositorBridgeChild::SendResumeAsync() {
+  if (!mCanSend) {
+    return false;
+  }
+  mPaused = false;
+  return PCompositorBridgeChild::SendResumeAsync();
+}
+
+bool CompositorBridgeChild::SendAdoptChild(const LayersId& id) {
+  if (!mCanSend) {
+    return false;
+  }
+  return PCompositorBridgeChild::SendAdoptChild(id);
+}
+
+bool CompositorBridgeChild::SendFlushRendering(
+    const wr::RenderReasons& aReasons) {
+  if (!mCanSend) {
+    return false;
+  }
+  return PCompositorBridgeChild::SendFlushRendering(aReasons);
+}
+
+bool CompositorBridgeChild::SendStartFrameTimeRecording(
+    const int32_t& bufferSize, uint32_t* startIndex) {
+  if (!mCanSend) {
+    return false;
+  }
+  return PCompositorBridgeChild::SendStartFrameTimeRecording(bufferSize,
+                                                             startIndex);
+}
+
+bool CompositorBridgeChild::SendStopFrameTimeRecording(
+    const uint32_t& startIndex, nsTArray<float>* intervals) {
+  if (!mCanSend) {
+    return false;
+  }
+  return PCompositorBridgeChild::SendStopFrameTimeRecording(startIndex,
+                                                            intervals);
+}
+
+PTextureChild* CompositorBridgeChild::AllocPTextureChild(
+    const SurfaceDescriptor&, ReadLockDescriptor&, const LayersBackend&,
+    const TextureFlags&, const LayersId&, const uint64_t& aSerial,
+    const wr::MaybeExternalImageId& aExternalImageId) {
+  return TextureClient::CreateIPDLActor();
+}
+
+bool CompositorBridgeChild::DeallocPTextureChild(PTextureChild* actor) {
+  return TextureClient::DestroyIPDLActor(actor);
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvParentAsyncMessages(
+    nsTArray<AsyncParentMessageData>&& aMessages) {
+  for (AsyncParentMessageArray::index_type i = 0; i < aMessages.Length(); ++i) {
+    const AsyncParentMessageData& message = aMessages[i];
+
+    switch (message.type()) {
+      case AsyncParentMessageData::TOpNotifyNotUsed: {
+        const OpNotifyNotUsed& op = message.get_OpNotifyNotUsed();
+        NotifyNotUsed(op.TextureId(), op.fwdTransactionId());
+        break;
+      }
+      default:
+        NS_ERROR("unknown AsyncParentMessageData type");
+        return IPC_FAIL_NO_REASON(this);
+    }
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvObserveLayersUpdate(
+    const LayersId& aLayersId, const bool& aActive) {
+  // This message is sent via the window compositor, not the tab compositor -
+  // however it still has a layers id.
+  MOZ_ASSERT(aLayersId.IsValid());
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (RefPtr<dom::BrowserParent> tab =
+          dom::BrowserParent::GetBrowserParentFromLayersId(aLayersId)) {
+    tab->LayerTreeUpdate(aActive);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvCompositorOptionsChanged(
+    const LayersId& aLayersId, const CompositorOptions& aNewOptions) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (RefPtr<dom::BrowserParent> tab =
+          dom::BrowserParent::GetBrowserParentFromLayersId(aLayersId)) {
+    Unused << tab->SendCompositorOptionsChanged(aNewOptions);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeChild::RecvNotifyJankedAnimations(
+    const LayersId& aLayersId, nsTArray<uint64_t>&& aJankedAnimations) {
+  if (mLayerManager) {
+    MOZ_ASSERT(!aLayersId.IsValid());
+    mLayerManager->UpdatePartialPrerenderedAnimations(aJankedAnimations);
+  } else if (aLayersId.IsValid()) {
+    RefPtr<dom::BrowserChild> child = dom::BrowserChild::GetFrom(aLayersId);
+    if (child) {
+      child->NotifyJankedAnimations(aJankedAnimations);
+    }
+  }
+
+  return IPC_OK();
+}
+
+void CompositorBridgeChild::HoldUntilCompositableRefReleasedIfNecessary(
+    TextureClient* aClient) {
+  if (!aClient) {
+    return;
+  }
+
+  bool waitNotifyNotUsed =
+      aClient->GetFlags() & TextureFlags::RECYCLE ||
+      aClient->GetFlags() & TextureFlags::WAIT_HOST_USAGE_END;
+  if (!waitNotifyNotUsed) {
+    return;
+  }
+
+  aClient->SetLastFwdTransactionId(
+      GetFwdTransactionCounter().mFwdTransactionId);
+  mTexturesWaitingNotifyNotUsed.emplace(aClient->GetSerial(), aClient);
+}
+
+void CompositorBridgeChild::NotifyNotUsed(uint64_t aTextureId,
+                                          uint64_t aFwdTransactionId) {
+  auto it = mTexturesWaitingNotifyNotUsed.find(aTextureId);
+  if (it != mTexturesWaitingNotifyNotUsed.end()) {
+    if (aFwdTransactionId < it->second->GetLastFwdTransactionId()) {
+      // Released on host side, but client already requested newer use texture.
+      return;
+    }
+    mTexturesWaitingNotifyNotUsed.erase(it);
+  }
+}
+
+void CompositorBridgeChild::CancelWaitForNotifyNotUsed(uint64_t aTextureId) {
+  mTexturesWaitingNotifyNotUsed.erase(aTextureId);
+}
+
+FixedSizeSmallShmemSectionAllocator*
+CompositorBridgeChild::GetTileLockAllocator() {
+  if (!IPCOpen()) {
+    return nullptr;
+  }
+
+  if (!mSectionAllocator) {
+    mSectionAllocator = new FixedSizeSmallShmemSectionAllocator(this);
+  }
+  return mSectionAllocator;
+}
+
+PTextureChild* CompositorBridgeChild::CreateTexture(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+    LayersBackend aLayersBackend, TextureFlags aFlags,
+    const dom::ContentParentId& aContentId, uint64_t aSerial,
+    wr::MaybeExternalImageId& aExternalImageId) {
+  PTextureChild* textureChild =
+      AllocPTextureChild(aSharedData, aReadLock, aLayersBackend, aFlags,
+                         LayersId{0} /* FIXME */, aSerial, aExternalImageId);
+
+  return SendPTextureConstructor(
+      textureChild, aSharedData, std::move(aReadLock), aLayersBackend, aFlags,
+      LayersId{0} /* FIXME? */, aSerial, aExternalImageId);
+}
+
+already_AddRefed<CanvasChild> CompositorBridgeChild::GetCanvasChild() {
+  MOZ_ASSERT(gfxPlatform::UseRemoteCanvas());
+  if (auto* cm = gfx::CanvasManagerChild::Get()) {
+    return cm->GetCanvasChild().forget();
+  }
+  return nullptr;
+}
+
+void CompositorBridgeChild::EndCanvasTransaction() {
+  if (auto* cm = gfx::CanvasManagerChild::Get()) {
+    cm->EndCanvasTransaction();
+  }
+}
+
+void CompositorBridgeChild::ClearCachedResources() {
+  if (auto* cm = gfx::CanvasManagerChild::Get()) {
+    cm->ClearCachedResources();
+  }
+}
+
+bool CompositorBridgeChild::AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) {
+  ShmemAllocated(this);
+  return PCompositorBridgeChild::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool CompositorBridgeChild::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  ShmemAllocated(this);
+  return PCompositorBridgeChild::AllocShmem(aSize, aShmem);
+}
+
+bool CompositorBridgeChild::DeallocShmem(ipc::Shmem& aShmem) {
+  if (!mCanSend) {
+    return false;
+  }
+  return PCompositorBridgeChild::DeallocShmem(aShmem);
+}
+
+widget::PCompositorWidgetChild*
+CompositorBridgeChild::AllocPCompositorWidgetChild(
+    const CompositorWidgetInitData& aInitData) {
+  // We send the constructor manually.
+  MOZ_CRASH("Should not be called");
+  return nullptr;
+}
+
+bool CompositorBridgeChild::DeallocPCompositorWidgetChild(
+    PCompositorWidgetChild* aActor) {
+#ifdef MOZ_WIDGET_SUPPORTS_OOP_COMPOSITING
+  delete aActor;
+  return true;
+#else
+  return false;
+#endif
+}
+
+PAPZCTreeManagerChild* CompositorBridgeChild::AllocPAPZCTreeManagerChild(
+    const LayersId& aLayersId) {
+  APZCTreeManagerChild* child = new APZCTreeManagerChild();
+  child->AddIPDLReference();
+
+  return child;
+}
+
+PAPZChild* CompositorBridgeChild::AllocPAPZChild(const LayersId& aLayersId) {
+  // We send the constructor manually.
+  MOZ_CRASH("Should not be called");
+  return nullptr;
+}
+
+bool CompositorBridgeChild::DeallocPAPZChild(PAPZChild* aActor) {
+  delete aActor;
+  return true;
+}
+
+bool CompositorBridgeChild::DeallocPAPZCTreeManagerChild(
+    PAPZCTreeManagerChild* aActor) {
+  APZCTreeManagerChild* child = static_cast<APZCTreeManagerChild*>(aActor);
+  child->ReleaseIPDLReference();
+  return true;
+}
+
+// -
+
+PWebRenderBridgeChild* CompositorBridgeChild::AllocPWebRenderBridgeChild(
+    const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize&,
+    const WindowKind&) {
+  WebRenderBridgeChild* child = new WebRenderBridgeChild(aPipelineId);
+  child->AddIPDLReference();
+  return child;
+}
+
+bool CompositorBridgeChild::DeallocPWebRenderBridgeChild(
+    PWebRenderBridgeChild* aActor) {
+  WebRenderBridgeChild* child = static_cast<WebRenderBridgeChild*>(aActor);
+  child->ReleaseIPDLReference();
+  return true;
+}
+
+uint64_t CompositorBridgeChild::GetNextResourceId() {
+  ++mResourceId;
+  MOZ_RELEASE_ASSERT(mResourceId != UINT32_MAX);
+
+  uint64_t id = mIdNamespace;
+  id = (id << 32) | mResourceId;
+
+  return id;
+}
+
+wr::MaybeExternalImageId CompositorBridgeChild::GetNextExternalImageId() {
+  return Some(wr::ToExternalImageId(GetNextResourceId()));
+}
+
+wr::PipelineId CompositorBridgeChild::GetNextPipelineId() {
+  return wr::AsPipelineId(GetNextResourceId());
+}
+
+FwdTransactionCounter& CompositorBridgeChild::GetFwdTransactionCounter() {
+  return mCompositorManager->GetFwdTransactionCounter();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositorBridgeChild.h b/gfx/layers/ipc/CompositorBridgeChild.h
new file mode 100644
index 0000000000..7e0a4799fe
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBridgeChild.h
@@ -0,0 +1,252 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorBridgeChild_h
+#define mozilla_layers_CompositorBridgeChild_h
+
+#include "base/basictypes.h"     // for DISALLOW_EVIL_CONSTRUCTORS
+#include "mozilla/Assertions.h"  // for MOZ_ASSERT_HELPER2
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/Monitor.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/layers/PCompositorBridgeChild.h"
+#include "mozilla/layers/TextureForwarder.h"  // for TextureForwarder
+#include "mozilla/webrender/WebRenderTypes.h"
+#include "nsClassHashtable.h"  // for nsClassHashtable
+#include "nsCOMPtr.h"          // for nsCOMPtr
+#include "nsHashKeys.h"        // for nsUint64HashKey
+#include "nsISupportsImpl.h"   // for NS_INLINE_DECL_REFCOUNTING
+#include "nsIWeakReferenceUtils.h"
+
+#include <unordered_map>
+
+namespace mozilla {
+
+namespace dom {
+class BrowserChild;
+}  // namespace dom
+
+namespace widget {
+class CompositorWidget;
+}  // namespace widget
+
+namespace layers {
+
+using mozilla::dom::BrowserChild;
+
+class IAPZCTreeManager;
+class APZCTreeManagerChild;
+class CanvasChild;
+class CompositorBridgeParent;
+class CompositorManagerChild;
+class CompositorOptions;
+class WebRenderLayerManager;
+class TextureClient;
+class TextureClientPool;
+struct FrameMetrics;
+struct FwdTransactionCounter;
+
+class CompositorBridgeChild final : public PCompositorBridgeChild,
+                                    public TextureForwarder {
+  typedef nsTArray<AsyncParentMessageData> AsyncParentMessageArray;
+
+  friend class PCompositorBridgeChild;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorBridgeChild, override);
+
+  explicit CompositorBridgeChild(CompositorManagerChild* aManager);
+
+  /**
+   * Initialize the singleton compositor bridge for a content process.
+   */
+  void InitForContent(uint32_t aNamespace);
+
+  void InitForWidget(uint64_t aProcessToken,
+                     WebRenderLayerManager* aLayerManager, uint32_t aNamespace);
+
+  void Destroy();
+
+  static CompositorBridgeChild* Get();
+
+  // Returns whether the compositor is in the GPU process (false if in the UI
+  // process). This may only be called on the main thread.
+  static bool CompositorIsInGPUProcess();
+
+  mozilla::ipc::IPCResult RecvDidComposite(
+      const LayersId& aId, const nsTArray<TransactionId>& aTransactionIds,
+      const TimeStamp& aCompositeStart, const TimeStamp& aCompositeEnd);
+
+  mozilla::ipc::IPCResult RecvNotifyFrameStats(
+      nsTArray<FrameStats>&& aFrameStats);
+
+  mozilla::ipc::IPCResult RecvNotifyJankedAnimations(
+      const LayersId& aLayersId, nsTArray<uint64_t>&& aJankedAnimations);
+
+  PTextureChild* AllocPTextureChild(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+      const LayersId& aId, const uint64_t& aSerial,
+      const wr::MaybeExternalImageId& aExternalImageId);
+
+  bool DeallocPTextureChild(PTextureChild* actor);
+
+  mozilla::ipc::IPCResult RecvParentAsyncMessages(
+      nsTArray<AsyncParentMessageData>&& aMessages);
+  PTextureChild* CreateTexture(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+      LayersBackend aLayersBackend, TextureFlags aFlags,
+      const dom::ContentParentId& aContentId, uint64_t aSerial,
+      wr::MaybeExternalImageId& aExternalImageId) override;
+
+  already_AddRefed<CanvasChild> GetCanvasChild() final;
+
+  void EndCanvasTransaction();
+
+  /**
+   * Release resources until they are next required.
+   */
+  void ClearCachedResources();
+
+  // Beware that these methods don't override their super-class equivalent
+  // (which are not virtual), they just overload them. All of these Send*
+  // methods just add a sanity check (that it is not too late send a message)
+  // and forward the call to the super-class's equivalent method. This means
+  // that it is correct to call directly the super-class methods, but you won't
+  // get the extra safety provided here.
+  bool SendWillClose();
+  bool SendPause();
+  bool SendResume();
+  bool SendResumeAsync();
+  bool SendAdoptChild(const LayersId& id);
+  bool SendFlushRendering(const wr::RenderReasons& aReasons);
+  bool SendStartFrameTimeRecording(const int32_t& bufferSize,
+                                   uint32_t* startIndex);
+  bool SendStopFrameTimeRecording(const uint32_t& startIndex,
+                                  nsTArray<float>* intervals);
+  bool IsSameProcess() const override;
+
+  bool IPCOpen() const override { return mCanSend; }
+
+  bool IsPaused() const { return mPaused; }
+
+  static void ShutDown();
+
+  FwdTransactionCounter& GetFwdTransactionCounter();
+
+  /**
+   * Hold TextureClient ref until end of usage on host side if
+   * TextureFlags::RECYCLE is set. Host side's usage is checked via
+   * CompositableRef.
+   */
+  void HoldUntilCompositableRefReleasedIfNecessary(TextureClient* aClient);
+
+  /**
+   * Notify id of Texture When host side end its use. Transaction id is used to
+   * make sure if there is no newer usage.
+   */
+  void NotifyNotUsed(uint64_t aTextureId, uint64_t aFwdTransactionId);
+
+  void CancelWaitForNotifyNotUsed(uint64_t aTextureId) override;
+
+  FixedSizeSmallShmemSectionAllocator* GetTileLockAllocator() override;
+
+  nsISerialEventTarget* GetThread() const override { return mThread; }
+
+  base::ProcessId GetParentPid() const override { return OtherPid(); }
+
+  bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+  PCompositorWidgetChild* AllocPCompositorWidgetChild(
+      const CompositorWidgetInitData& aInitData);
+  bool DeallocPCompositorWidgetChild(PCompositorWidgetChild* aActor);
+
+  PAPZCTreeManagerChild* AllocPAPZCTreeManagerChild(const LayersId& aLayersId);
+  bool DeallocPAPZCTreeManagerChild(PAPZCTreeManagerChild* aActor);
+
+  PAPZChild* AllocPAPZChild(const LayersId& aLayersId);
+  bool DeallocPAPZChild(PAPZChild* aActor);
+
+  PWebRenderBridgeChild* AllocPWebRenderBridgeChild(
+      const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize&,
+      const WindowKind&);
+  bool DeallocPWebRenderBridgeChild(PWebRenderBridgeChild* aActor);
+
+  wr::MaybeExternalImageId GetNextExternalImageId() override;
+
+  wr::PipelineId GetNextPipelineId();
+
+ private:
+  // Private destructor, to discourage deletion outside of Release():
+  virtual ~CompositorBridgeChild();
+
+  // Must only be called from the paint thread. If the main thread is delaying
+  // IPC messages, this forwards all such delayed IPC messages to the I/O thread
+  // and resumes IPC.
+  void ResumeIPCAfterAsyncPaint();
+
+  void PrepareFinalDestroy();
+  void AfterDestroy();
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  mozilla::ipc::IPCResult RecvObserveLayersUpdate(const LayersId& aLayersId,
+                                                  const bool& aActive);
+
+  mozilla::ipc::IPCResult RecvCompositorOptionsChanged(
+      const LayersId& aLayersId, const CompositorOptions& aNewOptions);
+
+  uint64_t GetNextResourceId();
+
+  RefPtr<CompositorManagerChild> mCompositorManager;
+
+  RefPtr<WebRenderLayerManager> mLayerManager;
+
+  uint32_t mIdNamespace;
+  uint32_t mResourceId;
+
+  // When not multi-process, hold a reference to the CompositorBridgeParent to
+  // keep it alive. This reference should be null in multi-process.
+  RefPtr<CompositorBridgeParent> mCompositorBridgeParent;
+
+  DISALLOW_EVIL_CONSTRUCTORS(CompositorBridgeChild);
+
+  // True until the beginning of the two-step shutdown sequence of this actor.
+  bool mCanSend;
+
+  // False until the actor is destroyed.
+  bool mActorDestroyed;
+
+  bool mPaused;
+
+  /**
+   * Hold TextureClients refs until end of their usages on host side.
+   * It defer calling of TextureClient recycle callback.
+   */
+  std::unordered_map<uint64_t, RefPtr<TextureClient>>
+      mTexturesWaitingNotifyNotUsed;
+
+  nsCOMPtr<nsISerialEventTarget> mThread;
+
+  AutoTArray<RefPtr<TextureClientPool>, 2> mTexturePools;
+
+  uint64_t mProcessToken;
+
+  FixedSizeSmallShmemSectionAllocator* mSectionAllocator;
+
+  // TextureClients that must be kept alive during async painting. This
+  // is only accessed on the main thread.
+  nsTArray<RefPtr<TextureClient>> mTextureClientsForAsyncPaint;
+
+  RefPtr<CanvasChild> mCanvasChild;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CompositorBrigedChild_h
diff --git a/gfx/layers/ipc/CompositorBridgeParent.cpp b/gfx/layers/ipc/CompositorBridgeParent.cpp
new file mode 100644
index 0000000000..3982791357
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBridgeParent.cpp
@@ -0,0 +1,2008 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/CompositorBridgeParent.h"
+
+#include <stdio.h>   // for fprintf, stdout
+#include <stdint.h>  // for uint64_t
+#include <map>       // for _Rb_tree_iterator, etc
+#include <utility>   // for pair
+
+#include "apz/src/APZCTreeManager.h"  // for APZCTreeManager
+#include "base/process.h"             // for ProcessId
+#include "gfxContext.h"               // for gfxContext
+#include "gfxPlatform.h"              // for gfxPlatform
+#include "TreeTraversal.h"            // for ForEachNode
+#ifdef MOZ_WIDGET_GTK
+#  include "gfxPlatformGtk.h"  // for gfxPlatform
+#endif
+#include "mozilla/AutoRestore.h"      // for AutoRestore
+#include "mozilla/ClearOnShutdown.h"  // for ClearOnShutdown
+#include "mozilla/DebugOnly.h"        // for DebugOnly
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_layers.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/gfx/2D.h"       // for DrawTarget
+#include "mozilla/gfx/Point.h"    // for IntSize
+#include "mozilla/gfx/Rect.h"     // for IntSize
+#include "mozilla/gfx/gfxVars.h"  // for gfxVars
+#include "mozilla/gfx/GPUParent.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/layers/APZCTreeManagerParent.h"  // for APZCTreeManagerParent
+#include "mozilla/layers/APZSampler.h"             // for APZSampler
+#include "mozilla/layers/APZThreadUtils.h"         // for APZThreadUtils
+#include "mozilla/layers/APZUpdater.h"             // for APZUpdater
+#include "mozilla/layers/CompositionRecorder.h"    // for CompositionRecorder
+#include "mozilla/layers/Compositor.h"             // for Compositor
+#include "mozilla/layers/CompositorAnimationStorage.h"  // for CompositorAnimationStorage
+#include "mozilla/layers/CompositorManagerParent.h"  // for CompositorManagerParent
+#include "mozilla/layers/CompositorOGL.h"            // for CompositorOGL
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/CompositorVsyncScheduler.h"
+#include "mozilla/layers/ContentCompositorBridgeParent.h"
+#include "mozilla/layers/FrameUniformityData.h"
+#include "mozilla/layers/GeckoContentController.h"
+#include "mozilla/layers/ImageBridgeParent.h"
+#include "mozilla/layers/LayerTreeOwnerTracker.h"
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/layers/OMTASampler.h"
+#include "mozilla/layers/RemoteContentController.h"
+#include "mozilla/layers/UiCompositorControllerParent.h"
+#include "mozilla/layers/WebRenderBridgeParent.h"
+#include "mozilla/layers/AsyncImagePipelineManager.h"
+#include "mozilla/webrender/WebRenderAPI.h"
+#include "mozilla/webrender/RenderThread.h"
+#include "mozilla/media/MediaSystemResourceService.h"  // for MediaSystemResourceService
+#include "mozilla/mozalloc.h"                          // for operator new, etc
+#include "mozilla/PodOperations.h"
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/glean/GleanMetrics.h"
+#include "nsCOMPtr.h"         // for already_AddRefed
+#include "nsDebug.h"          // for NS_ASSERTION, etc
+#include "nsISupportsImpl.h"  // for MOZ_COUNT_CTOR, etc
+#include "nsIWidget.h"        // for nsIWidget
+#include "nsTArray.h"         // for nsTArray
+#include "nsThreadUtils.h"    // for NS_IsMainThread
+#ifdef XP_WIN
+#  include "mozilla/layers/CompositorD3D11.h"
+#  include "mozilla/widget/WinCompositorWidget.h"
+#  include "mozilla/WindowsVersion.h"
+#endif
+#include "mozilla/ipc/ProtocolTypes.h"
+#include "mozilla/Unused.h"
+#include "mozilla/Hal.h"
+#include "mozilla/HalTypes.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/VsyncDispatcher.h"
+#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
+#  include "VsyncSource.h"
+#endif
+#include "mozilla/widget/CompositorWidget.h"
+#ifdef MOZ_WIDGET_SUPPORTS_OOP_COMPOSITING
+#  include "mozilla/widget/CompositorWidgetParent.h"
+#endif
+#ifdef XP_WIN
+#  include "mozilla/gfx/DeviceManagerDx.h"
+#endif
+
+namespace mozilla {
+
+namespace layers {
+
+using namespace mozilla::ipc;
+using namespace mozilla::gfx;
+
+using base::ProcessId;
+
+using mozilla::Telemetry::LABELS_CONTENT_FRAME_TIME_REASON;
+
+/* static*/
+StaticMonitor CompositorBridgeParent::sIndirectLayerTreesLock;
+
+/* static */
+CompositorBridgeParent::LayerTreeMap CompositorBridgeParent::sIndirectLayerTrees
+    MOZ_GUARDED_BY(CompositorBridgeParent::sIndirectLayerTreesLock);
+
+/// Equivalent to asserting CompositorThreadHolder::IsInCompositorThread with
+/// the addition that it doesn't assert if the compositor thread holder is
+/// already gone during late shutdown.
+static void AssertIsInCompositorThread() {
+  MOZ_RELEASE_ASSERT(!CompositorThread() ||
+                     CompositorThreadHolder::IsInCompositorThread());
+}
+
+CompositorBridgeParentBase::CompositorBridgeParentBase(
+    CompositorManagerParent* aManager)
+    : mCanSend(true), mCompositorManager(aManager) {}
+
+CompositorBridgeParentBase::~CompositorBridgeParentBase() = default;
+
+ProcessId CompositorBridgeParentBase::GetChildProcessId() { return OtherPid(); }
+
+dom::ContentParentId CompositorBridgeParentBase::GetContentId() {
+  return mCompositorManager->GetContentId();
+}
+
+void CompositorBridgeParentBase::NotifyNotUsed(PTextureParent* aTexture,
+                                               uint64_t aTransactionId) {
+  RefPtr<TextureHost> texture = TextureHost::AsTextureHost(aTexture);
+  if (!texture) {
+    return;
+  }
+
+  if (!(texture->GetFlags() & TextureFlags::RECYCLE) &&
+      !(texture->GetFlags() & TextureFlags::WAIT_HOST_USAGE_END)) {
+    return;
+  }
+
+  uint64_t textureId = TextureHost::GetTextureSerial(aTexture);
+  mPendingAsyncMessage.push_back(OpNotifyNotUsed(textureId, aTransactionId));
+}
+
+void CompositorBridgeParentBase::SendAsyncMessage(
+    const nsTArray<AsyncParentMessageData>& aMessage) {
+  Unused << SendParentAsyncMessages(aMessage);
+}
+
+bool CompositorBridgeParentBase::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  return PCompositorBridgeParent::AllocShmem(aSize, aShmem);
+}
+
+bool CompositorBridgeParentBase::AllocUnsafeShmem(size_t aSize,
+                                                  ipc::Shmem* aShmem) {
+  return PCompositorBridgeParent::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool CompositorBridgeParentBase::DeallocShmem(ipc::Shmem& aShmem) {
+  return PCompositorBridgeParent::DeallocShmem(aShmem);
+}
+
+CompositorBridgeParent::LayerTreeState::LayerTreeState()
+    : mApzcTreeManagerParent(nullptr),
+      mParent(nullptr),
+      mContentCompositorBridgeParent(nullptr) {}
+
+CompositorBridgeParent::LayerTreeState::~LayerTreeState() {
+  if (mController) {
+    mController->Destroy();
+  }
+}
+
+template <typename Lambda>
+inline void CompositorBridgeParent::ForEachIndirectLayerTree(
+    const Lambda& aCallback) {
+  sIndirectLayerTreesLock.AssertCurrentThreadOwns();
+  for (auto it = sIndirectLayerTrees.begin(); it != sIndirectLayerTrees.end();
+       it++) {
+    LayerTreeState* state = &it->second;
+    if (state->mParent == this) {
+      aCallback(state, it->first);
+    }
+  }
+}
+
+/*static*/ template <typename Lambda>
+inline void CompositorBridgeParent::ForEachWebRenderBridgeParent(
+    const Lambda& aCallback) {
+  sIndirectLayerTreesLock.AssertCurrentThreadOwns();
+  for (auto& it : sIndirectLayerTrees) {
+    LayerTreeState* state = &it.second;
+    if (state->mWrBridge) {
+      aCallback(state->mWrBridge);
+    }
+  }
+}
+
+/**
+ * A global map referencing each compositor by ID.
+ *
+ * This map is used by the ImageBridge protocol to trigger
+ * compositions without having to keep references to the
+ * compositor
+ */
+typedef std::map<uint64_t, CompositorBridgeParent*> CompositorMap;
+static StaticAutoPtr<CompositorMap> sCompositorMap;
+
+void CompositorBridgeParent::Setup() {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sCompositorMap);
+  sCompositorMap = new CompositorMap;
+}
+
+void CompositorBridgeParent::FinishShutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (sCompositorMap) {
+    MOZ_ASSERT(sCompositorMap->empty());
+    sCompositorMap = nullptr;
+  }
+
+  // TODO: this should be empty by now...
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  sIndirectLayerTrees.clear();
+}
+
+CompositorBridgeParent::CompositorBridgeParent(
+    CompositorManagerParent* aManager, CSSToLayoutDeviceScale aScale,
+    const TimeDuration& aVsyncRate, const CompositorOptions& aOptions,
+    bool aUseExternalSurfaceSize, const gfx::IntSize& aSurfaceSize,
+    uint64_t aInnerWindowId)
+    : CompositorBridgeParentBase(aManager),
+      mWidget(nullptr),
+      mScale(aScale),
+      mVsyncRate(aVsyncRate),
+      mPaused(false),
+      mHaveCompositionRecorder(false),
+      mIsForcedFirstPaint(false),
+      mUseExternalSurfaceSize(aUseExternalSurfaceSize),
+      mEGLSurfaceSize(aSurfaceSize),
+      mOptions(aOptions),
+      mCompositorBridgeID(0),
+      mRootLayerTreeID{0},
+      mInnerWindowId(aInnerWindowId),
+      mCompositorScheduler(nullptr),
+      mAnimationStorage(nullptr) {}
+
+void CompositorBridgeParent::InitSameProcess(widget::CompositorWidget* aWidget,
+                                             const LayersId& aLayerTreeId) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mWidget = aWidget;
+  mRootLayerTreeID = aLayerTreeId;
+#if defined(XP_WIN)
+  // when run in headless mode, no WinCompositorWidget is created
+  if (widget::WinCompositorWidget* windows = mWidget->AsWindows()) {
+    windows->SetRootLayerTreeID(mRootLayerTreeID);
+  }
+#endif
+
+  Initialize();
+}
+
+bool CompositorBridgeParent::IsPaused() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mPaused;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvInitialize(
+    const LayersId& aRootLayerTreeId) {
+  MOZ_ASSERT(XRE_IsGPUProcess());
+
+  mRootLayerTreeID = aRootLayerTreeId;
+#ifdef XP_WIN
+  // headless mode is probably always same-process; but just in case...
+  if (widget::WinCompositorWidget* windows = mWidget->AsWindows()) {
+    windows->SetRootLayerTreeID(mRootLayerTreeID);
+  }
+#endif
+
+  Initialize();
+  return IPC_OK();
+}
+
+void CompositorBridgeParent::Initialize() {
+  MOZ_ASSERT(CompositorThread(),
+             "The compositor thread must be Initialized before instanciating a "
+             "CompositorBridgeParent.");
+
+  if (mOptions.UseAPZ()) {
+    MOZ_ASSERT(!mApzcTreeManager);
+    MOZ_ASSERT(!mApzSampler);
+    MOZ_ASSERT(!mApzUpdater);
+    mApzcTreeManager = APZCTreeManager::Create(mRootLayerTreeID);
+    mApzSampler = new APZSampler(mApzcTreeManager, true);
+    mApzUpdater = new APZUpdater(mApzcTreeManager, true);
+  }
+
+  CompositorAnimationStorage* animationStorage = GetAnimationStorage();
+  mOMTASampler = new OMTASampler(animationStorage, mRootLayerTreeID);
+
+  mPaused = mOptions.InitiallyPaused();
+
+  mCompositorBridgeID = 0;
+  // FIXME: This holds on the the fact that right now the only thing that
+  // can destroy this instance is initialized on the compositor thread after
+  // this task has been processed.
+  MOZ_ASSERT(CompositorThread());
+  CompositorThread()->Dispatch(NewRunnableFunction(
+      "AddCompositorRunnable", &AddCompositor, this, &mCompositorBridgeID));
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    sIndirectLayerTrees[mRootLayerTreeID].mParent = this;
+  }
+}
+
+LayersId CompositorBridgeParent::RootLayerTreeId() {
+  MOZ_ASSERT(mRootLayerTreeID.IsValid());
+  return mRootLayerTreeID;
+}
+
+CompositorBridgeParent::~CompositorBridgeParent() {
+  MOZ_DIAGNOSTIC_ASSERT(
+      !mCanSend,
+      "ActorDestroy or RecvWillClose should have been called first.");
+  MOZ_DIAGNOSTIC_ASSERT(mRefCnt == 0,
+                        "ActorDealloc should have been called first.");
+  nsTArray<PTextureParent*> textures;
+  ManagedPTextureParent(textures);
+  // We expect all textures to be destroyed by now.
+  MOZ_DIAGNOSTIC_ASSERT(textures.Length() == 0);
+  for (unsigned int i = 0; i < textures.Length(); ++i) {
+    RefPtr<TextureHost> tex = TextureHost::AsTextureHost(textures[i]);
+    tex->DeallocateDeviceData();
+  }
+  // Check if WebRender/Compositor was shutdown.
+  if (mWrBridge) {
+    gfxCriticalNote << "CompositorBridgeParent destroyed without shutdown";
+  }
+}
+
+void CompositorBridgeParent::ForceIsFirstPaint() {
+  if (mWrBridge) {
+    mIsForcedFirstPaint = true;
+  }
+}
+
+void CompositorBridgeParent::StopAndClearResources() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mPaused = true;
+
+  // We need to clear the APZ tree before we destroy the WebRender API below,
+  // because in the case of async scene building that will shut down the updater
+  // thread and we need to run the task before that happens.
+  MOZ_ASSERT((mApzSampler != nullptr) == (mApzcTreeManager != nullptr));
+  MOZ_ASSERT((mApzUpdater != nullptr) == (mApzcTreeManager != nullptr));
+  if (mApzUpdater) {
+    mApzSampler->Destroy();
+    mApzSampler = nullptr;
+    mApzUpdater->ClearTree(mRootLayerTreeID);
+    mApzUpdater = nullptr;
+    mApzcTreeManager = nullptr;
+  }
+
+  if (mWrBridge) {
+    // Ensure we are not holding the sIndirectLayerTreesLock when destroying
+    // the WebRenderBridgeParent instances because it may block on WR.
+    std::vector<RefPtr<WebRenderBridgeParent>> indirectBridgeParents;
+    {  // scope lock
+      StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+      ForEachIndirectLayerTree([&](LayerTreeState* lts, LayersId) -> void {
+        if (lts->mWrBridge) {
+          indirectBridgeParents.emplace_back(lts->mWrBridge.forget());
+        }
+        lts->mParent = nullptr;
+      });
+    }
+    for (const RefPtr<WebRenderBridgeParent>& bridge : indirectBridgeParents) {
+      bridge->Destroy();
+    }
+    indirectBridgeParents.clear();
+
+    RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
+    // Ensure we are not holding the sIndirectLayerTreesLock here because we
+    // are going to block on WR threads in order to shut it down properly.
+    mWrBridge->Destroy();
+    mWrBridge = nullptr;
+
+    if (api) {
+      // Make extra sure we are done cleaning WebRender up before continuing.
+      // After that we wont have a way to talk to a lot of the webrender parts.
+      api->FlushSceneBuilder();
+      api = nullptr;
+    }
+
+    if (mAsyncImageManager) {
+      mAsyncImageManager->Destroy();
+      // WebRenderAPI should be already destructed
+      mAsyncImageManager = nullptr;
+    }
+  }
+
+  // This must be destroyed now since it accesses the widget.
+  if (mCompositorScheduler) {
+    mCompositorScheduler->Destroy();
+    mCompositorScheduler = nullptr;
+  }
+
+  if (mOMTASampler) {
+    mOMTASampler->Destroy();
+    mOMTASampler = nullptr;
+  }
+
+  // After this point, it is no longer legal to access the widget.
+  mWidget = nullptr;
+
+  // Clear mAnimationStorage here to ensure that the compositor thread
+  // still exists when we destroy it.
+  mAnimationStorage = nullptr;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvWillClose() {
+  StopAndClearResources();
+  // Once we get the WillClose message, the client side is going to go away
+  // soon and we can't be guaranteed that sending messages will work.
+  mCanSend = false;
+  return IPC_OK();
+}
+
+void CompositorBridgeParent::DeferredDestroy() {
+  MOZ_ASSERT(!NS_IsMainThread());
+  mSelfRef = nullptr;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvPause() {
+  PauseComposition();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvRequestFxrOutput() {
+#ifdef XP_WIN
+  // Continue forwarding the request to the Widget + SwapChain
+  mWidget->AsWindows()->RequestFxrOutput();
+#endif
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvResume() {
+  ResumeComposition();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvResumeAsync() {
+  ResumeComposition();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+CompositorBridgeParent::RecvWaitOnTransactionProcessed() {
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvFlushRendering(
+    const wr::RenderReasons& aReasons) {
+  if (mWrBridge) {
+    mWrBridge->FlushRendering(aReasons);
+    return IPC_OK();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvNotifyMemoryPressure() {
+  NotifyMemoryPressure();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvFlushRenderingAsync(
+    const wr::RenderReasons& aReasons) {
+  if (mWrBridge) {
+    mWrBridge->FlushRendering(aReasons, false);
+    return IPC_OK();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvForcePresent(
+    const wr::RenderReasons& aReasons) {
+  if (mWrBridge) {
+    mWrBridge->ScheduleForcedGenerateFrame(aReasons);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvStartFrameTimeRecording(
+    const int32_t& aBufferSize, uint32_t* aOutStartIndex) {
+  if (mWrBridge) {
+    *aOutStartIndex = mWrBridge->StartFrameTimeRecording(aBufferSize);
+  } else {
+    *aOutStartIndex = 0;
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvStopFrameTimeRecording(
+    const uint32_t& aStartIndex, nsTArray<float>* intervals) {
+  if (mWrBridge) {
+    mWrBridge->StopFrameTimeRecording(aStartIndex, *intervals);
+  }
+  return IPC_OK();
+}
+
+void CompositorBridgeParent::ActorDestroy(ActorDestroyReason why) {
+  mCanSend = false;
+
+  StopAndClearResources();
+
+  RemoveCompositor(mCompositorBridgeID);
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    sIndirectLayerTrees.erase(mRootLayerTreeID);
+  }
+
+  // There are chances that the ref count reaches zero on the main thread
+  // shortly after this function returns while some ipdl code still needs to run
+  // on this thread. We must keep the compositor parent alive untill the code
+  // handling message reception is finished on this thread.
+  mSelfRef = this;
+  NS_GetCurrentThread()->Dispatch(
+      NewRunnableMethod("layers::CompositorBridgeParent::DeferredDestroy", this,
+                        &CompositorBridgeParent::DeferredDestroy));
+}
+
+void CompositorBridgeParent::ScheduleRenderOnCompositorThread(
+    wr::RenderReasons aReasons) {
+  MOZ_ASSERT(CompositorThread());
+  CompositorThread()->Dispatch(NewRunnableMethod<wr::RenderReasons>(
+      "layers::CompositorBridgeParent::ScheduleComposition", this,
+      &CompositorBridgeParent::ScheduleComposition, aReasons));
+}
+
+void CompositorBridgeParent::PauseComposition() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread(),
+             "PauseComposition() can only be called on the compositor thread");
+
+  if (!mPaused) {
+    mPaused = true;
+
+    TimeStamp now = TimeStamp::Now();
+    if (mWrBridge) {
+      mWrBridge->Pause();
+      NotifyPipelineRendered(mWrBridge->PipelineId(),
+                             mWrBridge->GetCurrentEpoch(), VsyncId(), now, now,
+                             now);
+    }
+  }
+}
+
+bool CompositorBridgeParent::ResumeComposition() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread(),
+             "ResumeComposition() can only be called on the compositor thread");
+
+  bool resumed = mWidget->OnResumeComposition();
+  resumed = resumed && mWrBridge->Resume();
+
+  if (!resumed) {
+#ifdef MOZ_WIDGET_ANDROID
+    // We can't get a surface. This could be because the activity changed
+    // between the time resume was scheduled and now.
+    __android_log_print(
+        ANDROID_LOG_INFO, "CompositorBridgeParent",
+        "Unable to renew compositor surface; remaining in paused state");
+#endif
+    return false;
+  }
+
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mPaused = false;
+
+  mCompositorScheduler->ForceComposeToTarget(wr::RenderReasons::WIDGET, nullptr,
+                                             nullptr);
+  return true;
+}
+
+void CompositorBridgeParent::SetEGLSurfaceRect(int x, int y, int width,
+                                               int height) {
+  NS_ASSERTION(mUseExternalSurfaceSize,
+               "Compositor created without UseExternalSurfaceSize provided");
+  mEGLSurfaceSize.SizeTo(width, height);
+}
+
+bool CompositorBridgeParent::ResumeCompositionAndResize(int x, int y, int width,
+                                                        int height) {
+  SetEGLSurfaceRect(x, y, width, height);
+  return ResumeComposition();
+}
+
+void CompositorBridgeParent::ScheduleComposition(wr::RenderReasons aReasons) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (mPaused) {
+    return;
+  }
+
+  if (mWrBridge) {
+    mWrBridge->ScheduleGenerateFrame(aReasons);
+  }
+}
+
+PAPZCTreeManagerParent* CompositorBridgeParent::AllocPAPZCTreeManagerParent(
+    const LayersId& aLayersId) {
+  // This should only ever get called in the GPU process.
+  MOZ_ASSERT(XRE_IsGPUProcess());
+  // We should only ever get this if APZ is enabled in this compositor.
+  MOZ_ASSERT(mOptions.UseAPZ());
+  // The mApzcTreeManager and mApzUpdater should have been created via
+  // RecvInitialize()
+  MOZ_ASSERT(mApzcTreeManager);
+  MOZ_ASSERT(mApzUpdater);
+  // The main process should pass in 0 because we assume mRootLayerTreeID
+  MOZ_ASSERT(!aLayersId.IsValid());
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState& state =
+      sIndirectLayerTrees[mRootLayerTreeID];
+  MOZ_ASSERT(state.mParent.get() == this);
+  MOZ_ASSERT(!state.mApzcTreeManagerParent);
+  state.mApzcTreeManagerParent = new APZCTreeManagerParent(
+      mRootLayerTreeID, mApzcTreeManager, mApzUpdater);
+
+  return state.mApzcTreeManagerParent;
+}
+
+bool CompositorBridgeParent::DeallocPAPZCTreeManagerParent(
+    PAPZCTreeManagerParent* aActor) {
+  delete aActor;
+  return true;
+}
+
+void CompositorBridgeParent::AllocateAPZCTreeManagerParent(
+    const StaticMonitorAutoLock& aProofOfLayerTreeStateLock,
+    const LayersId& aLayersId, LayerTreeState& aState) {
+  MOZ_ASSERT(aState.mParent == this);
+  MOZ_ASSERT(mApzcTreeManager);
+  MOZ_ASSERT(mApzUpdater);
+  MOZ_ASSERT(!aState.mApzcTreeManagerParent);
+  aState.mApzcTreeManagerParent =
+      new APZCTreeManagerParent(aLayersId, mApzcTreeManager, mApzUpdater);
+}
+
+PAPZParent* CompositorBridgeParent::AllocPAPZParent(const LayersId& aLayersId) {
+  // This is the CompositorBridgeParent for a window, and so should only be
+  // creating a PAPZ instance if it lives in the GPU process. Instances that
+  // live in the UI process should going through SetControllerForLayerTree.
+  MOZ_RELEASE_ASSERT(XRE_IsGPUProcess());
+
+  // We should only ever get this if APZ is enabled on this compositor.
+  MOZ_RELEASE_ASSERT(mOptions.UseAPZ());
+
+  // The main process should pass in 0 because we assume mRootLayerTreeID
+  MOZ_RELEASE_ASSERT(!aLayersId.IsValid());
+
+  RemoteContentController* controller = new RemoteContentController();
+
+  // Increment the controller's refcount before we return it. This will keep the
+  // controller alive until it is released by IPDL in DeallocPAPZParent.
+  controller->AddRef();
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState& state =
+      sIndirectLayerTrees[mRootLayerTreeID];
+  MOZ_RELEASE_ASSERT(!state.mController);
+  state.mController = controller;
+
+  return controller;
+}
+
+bool CompositorBridgeParent::DeallocPAPZParent(PAPZParent* aActor) {
+  RemoteContentController* controller =
+      static_cast<RemoteContentController*>(aActor);
+  controller->Release();
+  return true;
+}
+
+RefPtr<APZSampler> CompositorBridgeParent::GetAPZSampler() const {
+  return mApzSampler;
+}
+
+RefPtr<APZUpdater> CompositorBridgeParent::GetAPZUpdater() const {
+  return mApzUpdater;
+}
+
+RefPtr<OMTASampler> CompositorBridgeParent::GetOMTASampler() const {
+  return mOMTASampler;
+}
+
+CompositorBridgeParent*
+CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+    const LayersId& aLayersId) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  return sIndirectLayerTrees[aLayersId].mParent;
+}
+
+/*static*/
+RefPtr<CompositorBridgeParent>
+CompositorBridgeParent::GetCompositorBridgeParentFromWindowId(
+    const wr::WindowId& aWindowId) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  for (auto it = sIndirectLayerTrees.begin(); it != sIndirectLayerTrees.end();
+       it++) {
+    LayerTreeState* state = &it->second;
+    if (!state->mWrBridge) {
+      continue;
+    }
+    // state->mWrBridge might be a root WebRenderBridgeParent or one of a
+    // content process, but in either case the state->mParent will be the same.
+    // So we don't need to distinguish between the two.
+    if (RefPtr<wr::WebRenderAPI> api = state->mWrBridge->GetWebRenderAPI()) {
+      if (api->GetId() == aWindowId) {
+        return state->mParent;
+      }
+    }
+  }
+  return nullptr;
+}
+
+bool CompositorBridgeParent::SetTestSampleTime(const LayersId& aId,
+                                               const TimeStamp& aTime) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  if (aTime.IsNull()) {
+    return false;
+  }
+
+  mTestTime = Some(aTime);
+  if (mApzcTreeManager) {
+    mApzcTreeManager->SetTestSampleTime(mTestTime);
+  }
+
+  if (mWrBridge) {
+    mWrBridge->FlushRendering(wr::RenderReasons::TESTING);
+    return true;
+  }
+
+  return true;
+}
+
+void CompositorBridgeParent::LeaveTestMode(const LayersId& aId) {
+  mTestTime = Nothing();
+  if (mApzcTreeManager) {
+    mApzcTreeManager->SetTestSampleTime(mTestTime);
+  }
+}
+
+CompositorAnimationStorage* CompositorBridgeParent::GetAnimationStorage() {
+  if (!mAnimationStorage) {
+    mAnimationStorage = new CompositorAnimationStorage(this);
+  }
+  return mAnimationStorage;
+}
+
+void CompositorBridgeParent::NotifyJankedAnimations(
+    const JankedAnimations& aJankedAnimations) {
+  MOZ_ASSERT(!aJankedAnimations.empty());
+
+  if (StaticPrefs::layout_animation_prerender_partial_jank()) {
+    return;
+  }
+
+  for (const auto& entry : aJankedAnimations) {
+    const LayersId& layersId = entry.first;
+    const nsTArray<uint64_t>& animations = entry.second;
+    if (layersId == mRootLayerTreeID) {
+      if (mWrBridge) {
+        Unused << SendNotifyJankedAnimations(LayersId{0}, animations);
+      }
+      // It unlikely happens multiple processes have janked animations at same
+      // time, so it should be fine with enumerating sIndirectLayerTrees every
+      // time.
+    } else if (const LayerTreeState* state = GetIndirectShadowTree(layersId)) {
+      if (ContentCompositorBridgeParent* cpcp =
+              state->mContentCompositorBridgeParent) {
+        Unused << cpcp->SendNotifyJankedAnimations(layersId, animations);
+      }
+    }
+  }
+}
+
+void CompositorBridgeParent::SetTestAsyncScrollOffset(
+    const LayersId& aLayersId, const ScrollableLayerGuid::ViewID& aScrollId,
+    const CSSPoint& aPoint) {
+  if (mApzUpdater) {
+    MOZ_ASSERT(aLayersId.IsValid());
+    mApzUpdater->SetTestAsyncScrollOffset(aLayersId, aScrollId, aPoint);
+  }
+}
+
+void CompositorBridgeParent::SetTestAsyncZoom(
+    const LayersId& aLayersId, const ScrollableLayerGuid::ViewID& aScrollId,
+    const LayerToParentLayerScale& aZoom) {
+  if (mApzUpdater) {
+    MOZ_ASSERT(aLayersId.IsValid());
+    mApzUpdater->SetTestAsyncZoom(aLayersId, aScrollId, aZoom);
+  }
+}
+
+void CompositorBridgeParent::FlushApzRepaints(const LayersId& aLayersId) {
+  MOZ_ASSERT(mApzUpdater);
+  MOZ_ASSERT(aLayersId.IsValid());
+  mApzUpdater->RunOnControllerThread(
+      aLayersId, NS_NewRunnableFunction(
+                     "layers::CompositorBridgeParent::FlushApzRepaints",
+                     [=]() { APZCTreeManager::FlushApzRepaints(aLayersId); }));
+}
+
+void CompositorBridgeParent::GetAPZTestData(const LayersId& aLayersId,
+                                            APZTestData* aOutData) {
+  if (mApzUpdater) {
+    MOZ_ASSERT(aLayersId.IsValid());
+    mApzUpdater->GetAPZTestData(aLayersId, aOutData);
+  }
+}
+
+void CompositorBridgeParent::GetFrameUniformity(const LayersId& aLayersId,
+                                                FrameUniformityData* aOutData) {
+}
+
+void CompositorBridgeParent::SetConfirmedTargetAPZC(
+    const LayersId& aLayersId, const uint64_t& aInputBlockId,
+    nsTArray<ScrollableLayerGuid>&& aTargets) {
+  if (!mApzcTreeManager || !mApzUpdater) {
+    return;
+  }
+  // Need to specifically bind this since it's overloaded.
+  void (APZCTreeManager::*setTargetApzcFunc)(
+      uint64_t, const nsTArray<ScrollableLayerGuid>&) =
+      &APZCTreeManager::SetTargetAPZC;
+  RefPtr<Runnable> task =
+      NewRunnableMethod<uint64_t,
+                        StoreCopyPassByRRef<nsTArray<ScrollableLayerGuid>>>(
+          "layers::CompositorBridgeParent::SetConfirmedTargetAPZC",
+          mApzcTreeManager.get(), setTargetApzcFunc, aInputBlockId,
+          std::move(aTargets));
+  mApzUpdater->RunOnUpdaterThread(aLayersId, task.forget());
+}
+
+void CompositorBridgeParent::SetFixedLayerMargins(ScreenIntCoord aTop,
+                                                  ScreenIntCoord aBottom) {
+  if (mApzcTreeManager) {
+    mApzcTreeManager->SetFixedLayerMargins(aTop, aBottom);
+  }
+
+  ScheduleComposition(wr::RenderReasons::RESIZE);
+}
+
+void CompositorBridgeParent::AddCompositor(CompositorBridgeParent* compositor,
+                                           uint64_t* outID) {
+  AssertIsInCompositorThread();
+
+  static uint64_t sNextID = 1;
+
+  ++sNextID;
+  (*sCompositorMap)[sNextID] = compositor;
+  *outID = sNextID;
+}
+
+CompositorBridgeParent* CompositorBridgeParent::RemoveCompositor(uint64_t id) {
+  AssertIsInCompositorThread();
+
+  CompositorMap::iterator it = sCompositorMap->find(id);
+  if (it == sCompositorMap->end()) {
+    return nullptr;
+  }
+  CompositorBridgeParent* retval = it->second;
+  sCompositorMap->erase(it);
+  return retval;
+}
+
+void CompositorBridgeParent::NotifyVsync(const VsyncEvent& aVsync,
+                                         const LayersId& aLayersId) {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_GPU);
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  auto it = sIndirectLayerTrees.find(aLayersId);
+  if (it == sIndirectLayerTrees.end()) return;
+
+  CompositorBridgeParent* cbp = it->second.mParent;
+  if (!cbp || !cbp->mWidget) return;
+
+  RefPtr<VsyncObserver> obs = cbp->mWidget->GetVsyncObserver();
+  if (!obs) return;
+
+  obs->NotifyVsync(aVsync);
+}
+
+/* static */
+void CompositorBridgeParent::ScheduleForcedComposition(
+    const LayersId& aLayersId, wr::RenderReasons aReasons) {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_GPU);
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  auto it = sIndirectLayerTrees.find(aLayersId);
+  if (it == sIndirectLayerTrees.end()) {
+    return;
+  }
+
+  CompositorBridgeParent* cbp = it->second.mParent;
+  if (!cbp || !cbp->mWidget) {
+    return;
+  }
+
+  if (cbp->mWrBridge) {
+    cbp->mWrBridge->ScheduleForcedGenerateFrame(aReasons);
+  }
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvNotifyChildCreated(
+    const LayersId& child, CompositorOptions* aOptions) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  NotifyChildCreated(child);
+  *aOptions = mOptions;
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvNotifyChildRecreated(
+    const LayersId& aChild, CompositorOptions* aOptions) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+
+  if (sIndirectLayerTrees.find(aChild) != sIndirectLayerTrees.end()) {
+    NS_WARNING("Invalid to register the same layer tree twice");
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  NotifyChildCreated(aChild);
+  *aOptions = mOptions;
+  return IPC_OK();
+}
+
+void CompositorBridgeParent::NotifyChildCreated(LayersId aChild) {
+  sIndirectLayerTreesLock.AssertCurrentThreadOwns();
+  sIndirectLayerTrees[aChild].mParent = this;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvMapAndNotifyChildCreated(
+    const LayersId& aChild, const base::ProcessId& aOwnerPid,
+    CompositorOptions* aOptions) {
+  // We only use this message when the remote compositor is in the GPU process.
+  // It is harmless to call it, though.
+  MOZ_ASSERT(XRE_IsGPUProcess());
+
+  LayerTreeOwnerTracker::Get()->Map(aChild, aOwnerPid);
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  NotifyChildCreated(aChild);
+  *aOptions = mOptions;
+  return IPC_OK();
+}
+
+enum class CompositorOptionsChangeKind {
+  eSupported,
+  eBestEffort,
+  eUnsupported
+};
+
+static CompositorOptionsChangeKind ClassifyCompositorOptionsChange(
+    const CompositorOptions& aOld, const CompositorOptions& aNew) {
+  if (aOld == aNew) {
+    return CompositorOptionsChangeKind::eSupported;
+  }
+  if (aOld.EqualsIgnoringApzEnablement(aNew)) {
+    return CompositorOptionsChangeKind::eBestEffort;
+  }
+  return CompositorOptionsChangeKind::eUnsupported;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvAdoptChild(
+    const LayersId& child) {
+  RefPtr<APZUpdater> oldApzUpdater;
+  APZCTreeManagerParent* parent;
+  bool apzEnablementChanged = false;
+  RefPtr<WebRenderBridgeParent> childWrBridge;
+
+  // Before adopting the child, save the old compositor's root content
+  // controller. We may need this to clear old layer transforms associated
+  // with the child.
+  // This is outside the lock because GetGeckoContentControllerForRoot()
+  // does its own locking.
+  RefPtr<GeckoContentController> oldRootController =
+      GetGeckoContentControllerForRoot(child);
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    // If child is already belong to this CompositorBridgeParent,
+    // no need to handle adopting child.
+    if (sIndirectLayerTrees[child].mParent == this) {
+      return IPC_OK();
+    }
+
+    if (sIndirectLayerTrees[child].mParent) {
+      switch (ClassifyCompositorOptionsChange(
+          sIndirectLayerTrees[child].mParent->mOptions, mOptions)) {
+        case CompositorOptionsChangeKind::eUnsupported: {
+          MOZ_ASSERT(false,
+                     "Moving tab between windows whose compositor options"
+                     "differ in unsupported ways. Things may break in "
+                     "unexpected ways");
+          break;
+        }
+        case CompositorOptionsChangeKind::eBestEffort: {
+          NS_WARNING(
+              "Moving tab between windows with different APZ enablement. "
+              "This is supported on a best-effort basis, but some things may "
+              "break.");
+          apzEnablementChanged = true;
+          break;
+        }
+        case CompositorOptionsChangeKind::eSupported: {
+          // The common case, no action required.
+          break;
+        }
+      }
+      oldApzUpdater = sIndirectLayerTrees[child].mParent->mApzUpdater;
+    }
+    if (mWrBridge) {
+      childWrBridge = sIndirectLayerTrees[child].mWrBridge;
+    }
+    parent = sIndirectLayerTrees[child].mApzcTreeManagerParent;
+  }
+
+  if (childWrBridge) {
+    MOZ_ASSERT(mWrBridge);
+    RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
+    api = api->Clone();
+    wr::Epoch newEpoch = childWrBridge->UpdateWebRender(
+        mWrBridge->CompositorScheduler(), std::move(api),
+        mWrBridge->AsyncImageManager(),
+        mWrBridge->GetTextureFactoryIdentifier());
+    // Pretend we composited, since parent CompositorBridgeParent was replaced.
+    TimeStamp now = TimeStamp::Now();
+    NotifyPipelineRendered(childWrBridge->PipelineId(), newEpoch, VsyncId(),
+                           now, now, now);
+  }
+
+  {
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    // Update sIndirectLayerTrees[child].mParent after
+    // WebRenderBridgeParent::UpdateWebRender().
+    NotifyChildCreated(child);
+  }
+
+  if (oldApzUpdater) {
+    // If we are moving a child from an APZ-enabled window to an APZ-disabled
+    // window (which can happen if e.g. a WebExtension moves a tab into a
+    // popup window), try to handle it gracefully by clearing the old layer
+    // transforms associated with the child. (Since the new compositor is
+    // APZ-disabled, there will be nothing to update the transforms going
+    // forward.)
+    if (!mApzUpdater && oldRootController) {
+      // Tell the old APZCTreeManager not to send any more layer transforms
+      // for this layers ids.
+      oldApzUpdater->MarkAsDetached(child);
+
+      // Clear the current transforms.
+      nsTArray<MatrixMessage> clear;
+      clear.AppendElement(MatrixMessage(Nothing(), ScreenRect(), child));
+      oldRootController->NotifyLayerTransforms(std::move(clear));
+    }
+  }
+  if (mApzUpdater) {
+    if (parent) {
+      MOZ_ASSERT(mApzcTreeManager);
+      parent->ChildAdopted(mApzcTreeManager, mApzUpdater);
+    }
+    mApzUpdater->NotifyLayerTreeAdopted(child, oldApzUpdater);
+  }
+  if (apzEnablementChanged) {
+    Unused << SendCompositorOptionsChanged(child, mOptions);
+  }
+  return IPC_OK();
+}
+
+PWebRenderBridgeParent* CompositorBridgeParent::AllocPWebRenderBridgeParent(
+    const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize& aSize,
+    const WindowKind& aWindowKind) {
+  MOZ_ASSERT(wr::AsLayersId(aPipelineId) == mRootLayerTreeID);
+  MOZ_ASSERT(!mWrBridge);
+  MOZ_ASSERT(!mCompositorScheduler);
+  MOZ_ASSERT(mWidget);
+
+#ifdef XP_WIN
+  if (mWidget && mWidget->AsWindows()) {
+    const auto options = mWidget->GetCompositorOptions();
+    if (!options.UseSoftwareWebRender() &&
+        (DeviceManagerDx::Get()->CanUseDComp() ||
+         gfxVars::UseWebRenderFlipSequentialWin())) {
+      mWidget->AsWindows()->EnsureCompositorWindow();
+    } else if (options.UseSoftwareWebRender() &&
+               mWidget->AsWindows()->GetCompositorHwnd()) {
+      mWidget->AsWindows()->DestroyCompositorWindow();
+    }
+  }
+#endif
+
+  RefPtr<widget::CompositorWidget> widget = mWidget;
+  wr::WrWindowId windowId = wr::NewWindowId();
+  if (mApzUpdater) {
+    // If APZ is enabled, we need to register the APZ updater with the window id
+    // before the updater thread is created in WebRenderAPI::Create, so
+    // that the callback from the updater thread can find the right APZUpdater.
+    mApzUpdater->SetWebRenderWindowId(windowId);
+  }
+  if (mApzSampler) {
+    // Same as for mApzUpdater, but for the sampler thread.
+    mApzSampler->SetWebRenderWindowId(windowId);
+  }
+  if (mOMTASampler) {
+    // Same, but for the OMTA sampler.
+    mOMTASampler->SetWebRenderWindowId(windowId);
+  }
+
+  nsCString error("FEATURE_FAILURE_WEBRENDER_INITIALIZE_UNSPECIFIED");
+  RefPtr<wr::WebRenderAPI> api = wr::WebRenderAPI::Create(
+      this, std::move(widget), windowId, aSize, aWindowKind, error);
+  if (!api) {
+    mWrBridge =
+        WebRenderBridgeParent::CreateDestroyed(aPipelineId, std::move(error));
+    mWrBridge.get()->AddRef();  // IPDL reference
+    return mWrBridge;
+  }
+
+#ifdef MOZ_WIDGET_ANDROID
+  // On Android, WebRenderAPI::Resume() call is triggered from Java side. But
+  // Java side does not know about fallback to RenderCompositorOGLSWGL. In this
+  // fallback case, RenderCompositor::Resume() needs to be called from gfx code.
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (!mPaused && mWidget->GetCompositorOptions().UseSoftwareWebRender() &&
+      mWidget->GetCompositorOptions().AllowSoftwareWebRenderOGL()) {
+    api->Resume();
+  }
+#endif
+
+  wr::TransactionBuilder txn(api);
+  txn.SetRootPipeline(aPipelineId);
+  api->SendTransaction(txn);
+
+  bool useCompositorWnd = false;
+#ifdef XP_WIN
+  // Headless mode uses HeadlessWidget.
+  if (mWidget->AsWindows()) {
+    useCompositorWnd = !!mWidget->AsWindows()->GetCompositorHwnd();
+  }
+#endif
+  mAsyncImageManager =
+      new AsyncImagePipelineManager(api->Clone(), useCompositorWnd);
+  RefPtr<AsyncImagePipelineManager> asyncMgr = mAsyncImageManager;
+  mWrBridge = new WebRenderBridgeParent(this, aPipelineId, mWidget, nullptr,
+                                        std::move(api), std::move(asyncMgr),
+                                        mVsyncRate);
+  mWrBridge.get()->AddRef();  // IPDL reference
+
+  mAsyncImageManager->SetTextureFactoryIdentifier(
+      mWrBridge->GetTextureFactoryIdentifier());
+
+  mCompositorScheduler = mWrBridge->CompositorScheduler();
+  MOZ_ASSERT(mCompositorScheduler);
+  {  // scope lock
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    MOZ_ASSERT(sIndirectLayerTrees[mRootLayerTreeID].mWrBridge == nullptr);
+    sIndirectLayerTrees[mRootLayerTreeID].mWrBridge = mWrBridge;
+  }
+  return mWrBridge;
+}
+
+bool CompositorBridgeParent::DeallocPWebRenderBridgeParent(
+    PWebRenderBridgeParent* aActor) {
+  WebRenderBridgeParent* parent = static_cast<WebRenderBridgeParent*>(aActor);
+  {
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    auto it = sIndirectLayerTrees.find(wr::AsLayersId(parent->PipelineId()));
+    if (it != sIndirectLayerTrees.end()) {
+      it->second.mWrBridge = nullptr;
+    }
+  }
+  parent->Release();  // IPDL reference
+  return true;
+}
+
+void CompositorBridgeParent::NotifyMemoryPressure() {
+  if (mWrBridge) {
+    RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
+    if (api) {
+      api->NotifyMemoryPressure();
+    }
+  }
+}
+
+void CompositorBridgeParent::AccumulateMemoryReport(wr::MemoryReport* aReport) {
+  if (mWrBridge) {
+    RefPtr<wr::WebRenderAPI> api = mWrBridge->GetWebRenderAPI();
+    if (api) {
+      api->AccumulateMemoryReport(aReport);
+    }
+  }
+}
+
+/*static*/
+void CompositorBridgeParent::InitializeStatics() {
+  gfxVars::SetForceSubpixelAAWherePossibleListener(&UpdateQualitySettings);
+  gfxVars::SetWebRenderDebugFlagsListener(&UpdateDebugFlags);
+  gfxVars::SetWebRenderBoolParametersListener(&UpdateWebRenderBoolParameters);
+  gfxVars::SetWebRenderBatchingLookbackListener(&UpdateWebRenderParameters);
+  gfxVars::SetWebRenderBlobTileSizeListener(&UpdateWebRenderParameters);
+  gfxVars::SetWebRenderBatchedUploadThresholdListener(
+      &UpdateWebRenderParameters);
+
+  gfxVars::SetWebRenderProfilerUIListener(&UpdateWebRenderProfilerUI);
+}
+
+/*static*/
+void CompositorBridgeParent::UpdateQualitySettings() {
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    if (CompositorThread()) {
+      CompositorThread()->Dispatch(
+          NewRunnableFunction("CompositorBridgeParent::UpdateQualitySettings",
+                              &CompositorBridgeParent::UpdateQualitySettings));
+    }
+
+    // If there is no compositor thread, e.g. due to shutdown, then we can
+    // safefully just ignore this request.
+    return;
+  }
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  ForEachWebRenderBridgeParent([&](WebRenderBridgeParent* wrBridge) -> void {
+    if (!wrBridge->IsRootWebRenderBridgeParent()) {
+      return;
+    }
+    wrBridge->UpdateQualitySettings();
+  });
+}
+
+/*static*/
+void CompositorBridgeParent::UpdateDebugFlags() {
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    if (CompositorThread()) {
+      CompositorThread()->Dispatch(
+          NewRunnableFunction("CompositorBridgeParent::UpdateDebugFlags",
+                              &CompositorBridgeParent::UpdateDebugFlags));
+    }
+
+    // If there is no compositor thread, e.g. due to shutdown, then we can
+    // safefully just ignore this request.
+    return;
+  }
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  ForEachWebRenderBridgeParent([&](WebRenderBridgeParent* wrBridge) -> void {
+    if (!wrBridge->IsRootWebRenderBridgeParent()) {
+      return;
+    }
+    wrBridge->UpdateDebugFlags();
+  });
+}
+
+/*static*/
+void CompositorBridgeParent::UpdateWebRenderBoolParameters() {
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    if (CompositorThread()) {
+      CompositorThread()->Dispatch(NewRunnableFunction(
+          "CompositorBridgeParent::UpdateWebRenderBoolParameters",
+          &CompositorBridgeParent::UpdateWebRenderBoolParameters));
+    }
+
+    return;
+  }
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  ForEachWebRenderBridgeParent([&](WebRenderBridgeParent* wrBridge) -> void {
+    if (!wrBridge->IsRootWebRenderBridgeParent()) {
+      return;
+    }
+    wrBridge->UpdateBoolParameters();
+  });
+}
+
+/*static*/
+void CompositorBridgeParent::UpdateWebRenderParameters() {
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    if (CompositorThread()) {
+      CompositorThread()->Dispatch(NewRunnableFunction(
+          "CompositorBridgeParent::UpdateWebRenderParameters",
+          &CompositorBridgeParent::UpdateWebRenderParameters));
+    }
+
+    return;
+  }
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  ForEachWebRenderBridgeParent([&](WebRenderBridgeParent* wrBridge) -> void {
+    if (!wrBridge->IsRootWebRenderBridgeParent()) {
+      return;
+    }
+    wrBridge->UpdateParameters();
+  });
+}
+
+/*static*/
+void CompositorBridgeParent::UpdateWebRenderProfilerUI() {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  ForEachWebRenderBridgeParent([&](WebRenderBridgeParent* wrBridge) -> void {
+    if (!wrBridge->IsRootWebRenderBridgeParent()) {
+      return;
+    }
+    wrBridge->UpdateProfilerUI();
+  });
+}
+
+RefPtr<WebRenderBridgeParent> CompositorBridgeParent::GetWebRenderBridgeParent()
+    const {
+  return mWrBridge;
+}
+
+Maybe<TimeStamp> CompositorBridgeParent::GetTestingTimeStamp() const {
+  return mTestTime;
+}
+
+void EraseLayerState(LayersId aId) {
+  RefPtr<APZUpdater> apz;
+  RefPtr<WebRenderBridgeParent> wrBridge;
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+    auto iter = CompositorBridgeParent::sIndirectLayerTrees.find(aId);
+    if (iter != CompositorBridgeParent::sIndirectLayerTrees.end()) {
+      CompositorBridgeParent* parent = iter->second.mParent;
+      if (parent) {
+        apz = parent->GetAPZUpdater();
+      }
+      wrBridge = iter->second.mWrBridge;
+      CompositorBridgeParent::sIndirectLayerTrees.erase(iter);
+    }
+  }
+
+  if (apz) {
+    apz->NotifyLayerTreeRemoved(aId);
+  }
+
+  if (wrBridge) {
+    wrBridge->Destroy();
+  }
+}
+
+/*static*/
+void CompositorBridgeParent::DeallocateLayerTreeId(LayersId aId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  // Here main thread notifies compositor to remove an element from
+  // sIndirectLayerTrees. This removed element might be queried soon.
+  // Checking the elements of sIndirectLayerTrees exist or not before using.
+  if (!CompositorThread()) {
+    gfxCriticalError() << "Attempting to post to an invalid Compositor Thread";
+    return;
+  }
+  CompositorThread()->Dispatch(
+      NewRunnableFunction("EraseLayerStateRunnable", &EraseLayerState, aId));
+}
+
+static void UpdateControllerForLayersId(LayersId aLayersId,
+                                        GeckoContentController* aController) {
+  // Adopt ref given to us by SetControllerForLayerTree()
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  CompositorBridgeParent::sIndirectLayerTrees[aLayersId].mController =
+      already_AddRefed<GeckoContentController>(aController);
+}
+
+ScopedLayerTreeRegistration::ScopedLayerTreeRegistration(
+    LayersId aLayersId, GeckoContentController* aController)
+    : mLayersId(aLayersId) {
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  CompositorBridgeParent::sIndirectLayerTrees[aLayersId].mController =
+      aController;
+}
+
+ScopedLayerTreeRegistration::~ScopedLayerTreeRegistration() {
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  CompositorBridgeParent::sIndirectLayerTrees.erase(mLayersId);
+}
+
+/*static*/
+void CompositorBridgeParent::SetControllerForLayerTree(
+    LayersId aLayersId, GeckoContentController* aController) {
+  // This ref is adopted by UpdateControllerForLayersId().
+  aController->AddRef();
+  CompositorThread()->Dispatch(NewRunnableFunction(
+      "UpdateControllerForLayersIdRunnable", &UpdateControllerForLayersId,
+      aLayersId, aController));
+}
+
+/*static*/
+already_AddRefed<IAPZCTreeManager> CompositorBridgeParent::GetAPZCTreeManager(
+    LayersId aLayersId) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  LayerTreeMap::iterator cit = sIndirectLayerTrees.find(aLayersId);
+  if (sIndirectLayerTrees.end() == cit) {
+    return nullptr;
+  }
+  LayerTreeState* lts = &cit->second;
+
+  RefPtr<IAPZCTreeManager> apzctm =
+      lts->mParent ? lts->mParent->mApzcTreeManager.get() : nullptr;
+  return apzctm.forget();
+}
+
+static void InsertVsyncProfilerMarker(TimeStamp aVsyncTimestamp) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (profiler_thread_is_being_profiled_for_markers()) {
+    // Tracks when a vsync occurs according to the HardwareComposer.
+    struct VsyncMarker {
+      static constexpr mozilla::Span<const char> MarkerTypeName() {
+        return mozilla::MakeStringSpan("VsyncTimestamp");
+      }
+      static void StreamJSONMarkerData(
+          baseprofiler::SpliceableJSONWriter& aWriter) {}
+      static MarkerSchema MarkerTypeDisplay() {
+        using MS = MarkerSchema;
+        MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable};
+        // Nothing outside the defaults.
+        return schema;
+      }
+    };
+    profiler_add_marker("VsyncTimestamp", geckoprofiler::category::GRAPHICS,
+                        MarkerTiming::InstantAt(aVsyncTimestamp),
+                        VsyncMarker{});
+  }
+}
+
+/*static */
+void CompositorBridgeParent::PostInsertVsyncProfilerMarker(
+    TimeStamp aVsyncTimestamp) {
+  // Called in the vsync thread
+  if (profiler_is_active() && CompositorThreadHolder::IsActive()) {
+    CompositorThread()->Dispatch(
+        NewRunnableFunction("InsertVsyncProfilerMarkerRunnable",
+                            InsertVsyncProfilerMarker, aVsyncTimestamp));
+  }
+}
+
+widget::PCompositorWidgetParent*
+CompositorBridgeParent::AllocPCompositorWidgetParent(
+    const CompositorWidgetInitData& aInitData) {
+#if defined(MOZ_WIDGET_SUPPORTS_OOP_COMPOSITING)
+  if (mWidget) {
+    // Should not create two widgets on the same compositor.
+    return nullptr;
+  }
+
+  widget::CompositorWidgetParent* widget =
+      new widget::CompositorWidgetParent(aInitData, mOptions);
+  widget->AddRef();
+
+  // Sending the constructor acts as initialization as well.
+  mWidget = widget;
+  return widget;
+#else
+  return nullptr;
+#endif
+}
+
+bool CompositorBridgeParent::DeallocPCompositorWidgetParent(
+    PCompositorWidgetParent* aActor) {
+#if defined(MOZ_WIDGET_SUPPORTS_OOP_COMPOSITING)
+  static_cast<widget::CompositorWidgetParent*>(aActor)->Release();
+  return true;
+#else
+  return false;
+#endif
+}
+
+CompositorController*
+CompositorBridgeParent::LayerTreeState::GetCompositorController() const {
+  return mParent;
+}
+
+void CompositorBridgeParent::NotifyDidSceneBuild(
+    RefPtr<const wr::WebRenderPipelineInfo> aInfo) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (mPaused) {
+    return;
+  }
+
+  if (mWrBridge) {
+    mWrBridge->NotifyDidSceneBuild(aInfo);
+  }
+}
+
+void CompositorBridgeParent::NotifyDidRender(const VsyncId& aCompositeStartId,
+                                             TimeStamp& aCompositeStart,
+                                             TimeStamp& aRenderStart,
+                                             TimeStamp& aCompositeEnd,
+                                             wr::RendererStats* aStats) {
+  if (!mWrBridge) {
+    return;
+  }
+
+  MOZ_RELEASE_ASSERT(mWrBridge->IsRootWebRenderBridgeParent());
+
+  RefPtr<UiCompositorControllerParent> uiController =
+      UiCompositorControllerParent::GetFromRootLayerTreeId(mRootLayerTreeID);
+
+  if (uiController && mIsForcedFirstPaint) {
+    uiController->NotifyFirstPaint();
+    mIsForcedFirstPaint = false;
+  }
+
+  nsTArray<CompositionPayload> payload =
+      mWrBridge->TakePendingScrollPayload(aCompositeStartId);
+  if (!payload.IsEmpty()) {
+    RecordCompositionPayloadsPresented(aCompositeEnd, payload);
+  }
+
+  nsTArray<ImageCompositeNotificationInfo> notifications;
+  mWrBridge->ExtractImageCompositeNotifications(&notifications);
+  if (!notifications.IsEmpty()) {
+    Unused << ImageBridgeParent::NotifyImageComposites(notifications);
+  }
+}
+
+bool CompositorBridgeParent::sStable = false;
+uint32_t CompositorBridgeParent::sFramesComposited = 0;
+
+/* static */ void CompositorBridgeParent::ResetStable() {
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    if (CompositorThread()) {
+      CompositorThread()->Dispatch(
+          NewRunnableFunction("CompositorBridgeParent::ResetStable",
+                              &CompositorBridgeParent::ResetStable));
+    }
+
+    // If there is no compositor thread, e.g. due to shutdown, then we can
+    // safefully just ignore this request.
+    return;
+  }
+
+  sStable = false;
+  sFramesComposited = 0;
+}
+
+void CompositorBridgeParent::MaybeDeclareStable() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  if (sStable) {
+    return;
+  }
+
+  // Once we render as many frames as the threshold, we declare this instance of
+  // the GPU process 'stable'. This causes the parent process to always respawn
+  // the GPU process if it crashes.
+  if (++sFramesComposited >=
+      StaticPrefs::layers_gpu_process_stable_frame_threshold()) {
+    sStable = true;
+
+    NS_DispatchToMainThread(NS_NewRunnableFunction(
+        "CompositorBridgeParent::MaybeDeclareStable", []() -> void {
+          if (XRE_IsParentProcess()) {
+            GPUProcessManager* gpm = GPUProcessManager::Get();
+            if (gpm) {
+              gpm->OnProcessDeclaredStable();
+            }
+          } else {
+            gfx::GPUParent* gpu = gfx::GPUParent::GetSingleton();
+            if (gpu && gpu->CanSend()) {
+              Unused << gpu->SendDeclareStable();
+            }
+          }
+        }));
+  }
+}
+
+void CompositorBridgeParent::NotifyPipelineRendered(
+    const wr::PipelineId& aPipelineId, const wr::Epoch& aEpoch,
+    const VsyncId& aCompositeStartId, TimeStamp& aCompositeStart,
+    TimeStamp& aRenderStart, TimeStamp& aCompositeEnd,
+    wr::RendererStats* aStats) {
+  if (!mWrBridge || !mAsyncImageManager) {
+    return;
+  }
+
+  bool isRoot = mWrBridge->PipelineId() == aPipelineId;
+  RefPtr<WebRenderBridgeParent> wrBridge =
+      isRoot ? mWrBridge
+             : RefPtr<WebRenderBridgeParent>(
+                   mAsyncImageManager->GetWrBridge(aPipelineId));
+  if (!wrBridge) {
+    return;
+  }
+
+  CompositorBridgeParentBase* compBridge =
+      isRoot ? this : wrBridge->GetCompositorBridge();
+  if (!compBridge) {
+    return;
+  }
+
+  MOZ_RELEASE_ASSERT(isRoot == wrBridge->IsRootWebRenderBridgeParent());
+
+  wrBridge->RemoveEpochDataPriorTo(aEpoch);
+
+  nsTArray<FrameStats> stats;
+  nsTArray<TransactionId> transactions;
+
+  RefPtr<UiCompositorControllerParent> uiController =
+      UiCompositorControllerParent::GetFromRootLayerTreeId(mRootLayerTreeID);
+
+  wrBridge->FlushTransactionIdsForEpoch(
+      aEpoch, aCompositeStartId, aCompositeStart, aRenderStart, aCompositeEnd,
+      uiController, aStats, stats, transactions);
+  if (transactions.IsEmpty()) {
+    MOZ_ASSERT(stats.IsEmpty());
+    return;
+  }
+
+  MaybeDeclareStable();
+
+  LayersId layersId = isRoot ? LayersId{0} : wrBridge->GetLayersId();
+  Unused << compBridge->SendDidComposite(layersId, transactions,
+                                         aCompositeStart, aCompositeEnd);
+
+  if (!stats.IsEmpty()) {
+    Unused << SendNotifyFrameStats(stats);
+  }
+}
+
+RefPtr<AsyncImagePipelineManager>
+CompositorBridgeParent::GetAsyncImagePipelineManager() const {
+  return mAsyncImageManager;
+}
+
+/* static */ CompositorBridgeParent::LayerTreeState*
+CompositorBridgeParent::GetIndirectShadowTree(LayersId aId) {
+  // Only the compositor thread should use this method variant
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  LayerTreeMap::iterator cit = sIndirectLayerTrees.find(aId);
+  if (sIndirectLayerTrees.end() == cit) {
+    return nullptr;
+  }
+  return &cit->second;
+}
+
+/* static */
+bool CompositorBridgeParent::CallWithIndirectShadowTree(
+    LayersId aId,
+    const std::function<void(CompositorBridgeParent::LayerTreeState&)>& aFunc) {
+  // Note that this does not make things universally threadsafe just because the
+  // sIndirectLayerTreesLock mutex is held. This is because the compositor
+  // thread can mutate the LayerTreeState outside the lock. It does however
+  // ensure that the *storage* for the LayerTreeState remains stable, since we
+  // should always hold the lock when adding/removing entries to the map.
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  LayerTreeMap::iterator cit = sIndirectLayerTrees.find(aId);
+  if (sIndirectLayerTrees.end() == cit) {
+    return false;
+  }
+  aFunc(cit->second);
+  return true;
+}
+
+static CompositorBridgeParent::LayerTreeState* GetStateForRoot(
+    LayersId aContentLayersId, const StaticMonitorAutoLock& aProofOfLock) {
+  CompositorBridgeParent::sIndirectLayerTreesLock.AssertCurrentThreadOwns();
+  CompositorBridgeParent::LayerTreeState* contentState = nullptr;
+  auto itr = CompositorBridgeParent::sIndirectLayerTrees.find(aContentLayersId);
+  if (CompositorBridgeParent::sIndirectLayerTrees.end() != itr) {
+    contentState = &itr->second;
+  }
+
+  // |contentState| is the state for the content process, but we want the
+  // APZCTMParent for the parent process owning that content process. So we have
+  // to jump to the LayerTreeState for the root layer tree id for that layer
+  // tree, and use the mApzcTreeManagerParent from that. This should also work
+  // with nested content processes, because RootLayerTreeId() will bypass any
+  // intermediate processes' ids and go straight to the root.
+  if (contentState && contentState->mParent) {
+    LayersId rootLayersId = contentState->mParent->RootLayerTreeId();
+    itr = CompositorBridgeParent::sIndirectLayerTrees.find(rootLayersId);
+    CompositorBridgeParent::LayerTreeState* rootState =
+        (CompositorBridgeParent::sIndirectLayerTrees.end() != itr)
+            ? &itr->second
+            : nullptr;
+    return rootState;
+  }
+
+  // Don't return contentState, that would be a lie!
+  return nullptr;
+}
+
+/* static */
+APZCTreeManagerParent* CompositorBridgeParent::GetApzcTreeManagerParentForRoot(
+    LayersId aContentLayersId) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState* state =
+      GetStateForRoot(aContentLayersId, lock);
+  return state ? state->mApzcTreeManagerParent : nullptr;
+}
+
+/* static */
+GeckoContentController*
+CompositorBridgeParent::GetGeckoContentControllerForRoot(
+    LayersId aContentLayersId) {
+  StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState* state =
+      GetStateForRoot(aContentLayersId, lock);
+  return state ? state->mController.get() : nullptr;
+}
+
+PTextureParent* CompositorBridgeParent::AllocPTextureParent(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+    const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+    const LayersId& aId, const uint64_t& aSerial,
+    const wr::MaybeExternalImageId& aExternalImageId) {
+  return TextureHost::CreateIPDLActor(
+      this, aSharedData, std::move(aReadLock), aLayersBackend, aFlags,
+      mCompositorManager->GetContentId(), aSerial, aExternalImageId);
+}
+
+bool CompositorBridgeParent::DeallocPTextureParent(PTextureParent* actor) {
+  return TextureHost::DestroyIPDLActor(actor);
+}
+
+bool CompositorBridgeParent::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void CompositorBridgeParent::NotifyWebRenderDisableNativeCompositor() {
+  MOZ_ASSERT(CompositorThread()->IsOnCurrentThread());
+  if (mWrBridge) {
+    mWrBridge->DisableNativeCompositor();
+  }
+}
+
+int32_t RecordContentFrameTime(
+    const VsyncId& aTxnId, const TimeStamp& aVsyncStart,
+    const TimeStamp& aTxnStart, const VsyncId& aCompositeId,
+    const TimeStamp& aCompositeEnd, const TimeDuration& aFullPaintTime,
+    const TimeDuration& aVsyncRate, bool aContainsSVGGroup,
+    bool aRecordUploadStats, wr::RendererStats* aStats /* = nullptr */) {
+  double latencyMs = (aCompositeEnd - aTxnStart).ToMilliseconds();
+  double latencyNorm = latencyMs / aVsyncRate.ToMilliseconds();
+  int32_t fracLatencyNorm = lround(latencyNorm * 100.0);
+
+  if (profiler_thread_is_being_profiled_for_markers()) {
+    struct ContentFrameMarker {
+      static constexpr Span<const char> MarkerTypeName() {
+        return MakeStringSpan("CONTENT_FRAME_TIME");
+      }
+      static void StreamJSONMarkerData(
+          baseprofiler::SpliceableJSONWriter& aWriter) {}
+      static MarkerSchema MarkerTypeDisplay() {
+        using MS = MarkerSchema;
+        MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable};
+        // Nothing outside the defaults.
+        return schema;
+      }
+    };
+
+    profiler_add_marker("CONTENT_FRAME_TIME", geckoprofiler::category::GRAPHICS,
+                        MarkerTiming::Interval(aTxnStart, aCompositeEnd),
+                        ContentFrameMarker{});
+  }
+
+  mozilla::glean::gfx_content_frame_time::from_paint.AccumulateSamples(
+      {static_cast<unsigned long long>(fracLatencyNorm)});
+
+  if (!(aTxnId == VsyncId()) && aVsyncStart) {
+    latencyMs = (aCompositeEnd - aVsyncStart).ToMilliseconds();
+    latencyNorm = latencyMs / aVsyncRate.ToMilliseconds();
+    fracLatencyNorm = lround(latencyNorm * 100.0);
+    int32_t result = fracLatencyNorm;
+    mozilla::glean::gfx_content_frame_time::from_vsync.AccumulateSamples(
+        {static_cast<unsigned long long>(fracLatencyNorm)});
+
+    if (aContainsSVGGroup) {
+      mozilla::glean::gfx_content_frame_time::with_svg.AccumulateSamples(
+          {static_cast<unsigned long long>(fracLatencyNorm)});
+    }
+
+    // Record CONTENT_FRAME_TIME_REASON.
+    //
+    // Note that deseralizing a layers update (RecvUpdate) can delay the receipt
+    // of the composite vsync message
+    // (CompositorBridgeParent::CompositeToTarget), since they're using the same
+    // thread. This can mean that compositing might start significantly late,
+    // but this code will still detect it as having successfully started on the
+    // right vsync (which is somewhat correct). We'd now have reduced time left
+    // in the vsync interval to finish compositing, so the chances of a missed
+    // frame increases. This is effectively including the RecvUpdate work as
+    // part of the 'compositing' phase for this metric, but it isn't included in
+    // COMPOSITE_TIME, and *is* included in CONTENT_FULL_PAINT_TIME.
+    //
+    // Also of note is that when the root WebRenderBridgeParent decides to
+    // skip a composite (due to the Renderer being busy), that won't notify
+    // child WebRenderBridgeParents. That failure will show up as the
+    // composite starting late (since it did), but it's really a fault of a
+    // slow composite on the previous frame, not a slow
+    // CONTENT_FULL_PAINT_TIME. It would be nice to have a separate bucket for
+    // this category (scene was ready on the next vsync, but we chose not to
+    // composite), but I can't find a way to locate the right child
+    // WebRenderBridgeParents from the root. WebRender notifies us of the
+    // child pipelines contained within a render, after it finishes, but I
+    // can't see how to query what child pipeline would have been rendered,
+    // when we choose to not do it.
+    if (fracLatencyNorm < 200) {
+      // Success
+      Telemetry::AccumulateCategorical(
+          LABELS_CONTENT_FRAME_TIME_REASON::OnTime);
+      mozilla::glean::gfx_content_frame_time::reason
+          .EnumGet(glean::gfx_content_frame_time::ReasonLabel::eOnTime)
+          .Add();
+    } else {
+      if (aCompositeId == VsyncId()) {
+        // aCompositeId is 0, possibly something got trigged from
+        // outside vsync?
+        Telemetry::AccumulateCategorical(
+            LABELS_CONTENT_FRAME_TIME_REASON::NoVsyncNoId);
+        mozilla::glean::gfx_content_frame_time::reason
+            .EnumGet(glean::gfx_content_frame_time::ReasonLabel::eNoVsyncNoId)
+            .Add();
+      } else if (aTxnId >= aCompositeId) {
+        // Vsync ids are nonsensical, maybe we're trying to catch up?
+        Telemetry::AccumulateCategorical(
+            LABELS_CONTENT_FRAME_TIME_REASON::NoVsync);
+        mozilla::glean::gfx_content_frame_time::reason
+            .EnumGet(glean::gfx_content_frame_time::ReasonLabel::eNoVsync)
+            .Add();
+      } else if (aCompositeId - aTxnId > 1) {
+        // Composite started late (and maybe took too long as well)
+        if (aFullPaintTime >= TimeDuration::FromMilliseconds(20)) {
+          Telemetry::AccumulateCategorical(
+              LABELS_CONTENT_FRAME_TIME_REASON::MissedCompositeLong);
+          mozilla::glean::gfx_content_frame_time::reason
+              .EnumGet(glean::gfx_content_frame_time::ReasonLabel::
+                           eMissedCompositeLong)
+              .Add();
+        } else if (aFullPaintTime >= TimeDuration::FromMilliseconds(10)) {
+          Telemetry::AccumulateCategorical(
+              LABELS_CONTENT_FRAME_TIME_REASON::MissedCompositeMid);
+          mozilla::glean::gfx_content_frame_time::reason
+              .EnumGet(glean::gfx_content_frame_time::ReasonLabel::
+                           eMissedCompositeMid)
+              .Add();
+        } else if (aFullPaintTime >= TimeDuration::FromMilliseconds(5)) {
+          Telemetry::AccumulateCategorical(
+              LABELS_CONTENT_FRAME_TIME_REASON::MissedCompositeLow);
+          mozilla::glean::gfx_content_frame_time::reason
+              .EnumGet(glean::gfx_content_frame_time::ReasonLabel::
+                           eMissedCompositeLow)
+              .Add();
+        } else {
+          Telemetry::AccumulateCategorical(
+              LABELS_CONTENT_FRAME_TIME_REASON::MissedComposite);
+          mozilla::glean::gfx_content_frame_time::reason
+              .EnumGet(
+                  glean::gfx_content_frame_time::ReasonLabel::eMissedComposite)
+              .Add();
+        }
+      } else {
+        // Composite started on time, but must have taken too long.
+        Telemetry::AccumulateCategorical(
+            LABELS_CONTENT_FRAME_TIME_REASON::SlowComposite);
+        mozilla::glean::gfx_content_frame_time::reason
+            .EnumGet(glean::gfx_content_frame_time::ReasonLabel::eSlowComposite)
+            .Add();
+      }
+    }
+
+    if (aRecordUploadStats) {
+      if (aStats) {
+        latencyMs -= (double(aStats->resource_upload_time) / 1000000.0);
+        latencyNorm = latencyMs / aVsyncRate.ToMilliseconds();
+        fracLatencyNorm = lround(latencyNorm * 100.0);
+      }
+      mozilla::glean::gfx_content_frame_time::without_resource_upload
+          .AccumulateSamples(
+              {static_cast<unsigned long long>(fracLatencyNorm)});
+
+      if (aStats) {
+        latencyMs -= (double(aStats->gpu_cache_upload_time) / 1000000.0);
+        latencyNorm = latencyMs / aVsyncRate.ToMilliseconds();
+        fracLatencyNorm = lround(latencyNorm * 100.0);
+      }
+      mozilla::glean::gfx_content_frame_time::without_resource_upload
+          .AccumulateSamples(
+              {static_cast<unsigned long long>(fracLatencyNorm)});
+    }
+    return result;
+  }
+
+  return 0;
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvBeginRecording(
+    const TimeStamp& aRecordingStart, BeginRecordingResolver&& aResolve) {
+  if (mHaveCompositionRecorder) {
+    aResolve(false);
+    return IPC_OK();
+  }
+
+  if (mWrBridge) {
+    mWrBridge->BeginRecording(aRecordingStart);
+  }
+
+  mHaveCompositionRecorder = true;
+  aResolve(true);
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorBridgeParent::RecvEndRecording(
+    EndRecordingResolver&& aResolve) {
+  if (!mHaveCompositionRecorder) {
+    aResolve(Nothing());
+    return IPC_OK();
+  }
+
+  if (mWrBridge) {
+    mWrBridge->EndRecording()->Then(
+        NS_GetCurrentThread(), __func__,
+        [resolve{aResolve}](FrameRecording&& recording) {
+          resolve(Some(std::move(recording)));
+        },
+        [resolve{aResolve}]() { resolve(Nothing()); });
+  } else {
+    aResolve(Nothing());
+  }
+
+  mHaveCompositionRecorder = false;
+
+  return IPC_OK();
+}
+
+void CompositorBridgeParent::FlushPendingWrTransactionEventsWithWait() {
+  if (!mWrBridge) {
+    return;
+  }
+
+  std::vector<RefPtr<WebRenderBridgeParent>> bridgeParents;
+  {  // scope lock
+    StaticMonitorAutoLock lock(sIndirectLayerTreesLock);
+    ForEachIndirectLayerTree([&](LayerTreeState* lts, LayersId) -> void {
+      if (lts->mWrBridge) {
+        bridgeParents.emplace_back(lts->mWrBridge);
+      }
+    });
+  }
+
+  for (auto& bridge : bridgeParents) {
+    bridge->FlushPendingWrTransactionEventsWithWait();
+  }
+}
+
+void RecordCompositionPayloadsPresented(
+    const TimeStamp& aCompositionEndTime,
+    const nsTArray<CompositionPayload>& aPayloads) {
+  if (aPayloads.Length()) {
+    TimeStamp presented = aCompositionEndTime;
+    for (const CompositionPayload& payload : aPayloads) {
+      if (profiler_thread_is_being_profiled_for_markers()) {
+        MOZ_RELEASE_ASSERT(payload.mType <= kHighestCompositionPayloadType);
+        nsAutoCString name(
+            kCompositionPayloadTypeNames[uint8_t(payload.mType)]);
+        name.AppendLiteral(" Payload Presented");
+        // This doesn't really need to be a text marker. Once we have a version
+        // of profiler_add_marker that accepts both a start time and an end
+        // time, we could use that here.
+        nsPrintfCString text(
+            "Latency: %dms",
+            int32_t((presented - payload.mTimeStamp).ToMilliseconds()));
+        PROFILER_MARKER_TEXT(
+            name, GRAPHICS,
+            MarkerTiming::Interval(payload.mTimeStamp, presented), text);
+      }
+
+      if (payload.mType == CompositionPayloadType::eKeyPress) {
+        glean::performance_interaction::keypress_present_latency
+            .AccumulateRawDuration(presented - payload.mTimeStamp);
+      } else if (payload.mType == CompositionPayloadType::eAPZScroll) {
+        mozilla::glean::gfx::scroll_present_latency.AccumulateRawDuration(
+            presented - payload.mTimeStamp);
+      } else if (payload.mType ==
+                 CompositionPayloadType::eMouseUpFollowedByClick) {
+        glean::performance_interaction::mouseup_click_present_latency
+            .AccumulateRawDuration(presented - payload.mTimeStamp);
+      }
+    }
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositorBridgeParent.h b/gfx/layers/ipc/CompositorBridgeParent.h
new file mode 100644
index 0000000000..0e6bd48f9a
--- /dev/null
+++ b/gfx/layers/ipc/CompositorBridgeParent.h
@@ -0,0 +1,648 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorBridgeParent_h
+#define mozilla_layers_CompositorBridgeParent_h
+
+#include <stdint.h>  // for uint64_t
+#include <unordered_map>
+#include "mozilla/Assertions.h"  // for MOZ_ASSERT_HELPER2
+#include "mozilla/Maybe.h"
+#include "mozilla/Monitor.h"        // for Monitor
+#include "mozilla/RefPtr.h"         // for RefPtr
+#include "mozilla/StaticMonitor.h"  // for StaticMonitor
+#include "mozilla/TimeStamp.h"      // for TimeStamp
+#include "mozilla/gfx/Point.h"      // for IntSize
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/ipc/SharedMemory.h"
+#include "mozilla/layers/CompositorController.h"
+#include "mozilla/layers/CompositorVsyncSchedulerOwner.h"
+#include "mozilla/layers/FocusTarget.h"
+#include "mozilla/layers/ISurfaceAllocator.h"  // for IShmemAllocator
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/layers/PCompositorBridgeParent.h"
+#include "mozilla/webrender/WebRenderTypes.h"
+
+namespace mozilla {
+
+namespace gfx {
+class GPUProcessManager;
+class GPUParent;
+}  // namespace gfx
+
+namespace ipc {
+class Shmem;
+}  // namespace ipc
+
+namespace widget {
+class CompositorWidget;
+}
+
+namespace wr {
+class WebRenderPipelineInfo;
+struct Epoch;
+struct MemoryReport;
+struct PipelineId;
+struct RendererStats;
+}  // namespace wr
+
+namespace layers {
+
+class APZCTreeManager;
+class APZCTreeManagerParent;
+class APZSampler;
+class APZTestData;
+class APZUpdater;
+class AsyncImagePipelineManager;
+class CompositorAnimationStorage;
+class CompositorBridgeParent;
+class CompositorManagerParent;
+class CompositorVsyncScheduler;
+class FrameUniformityData;
+class GeckoContentController;
+class IAPZCTreeManager;
+class OMTASampler;
+class ContentCompositorBridgeParent;
+class CompositorThreadHolder;
+class InProcessCompositorSession;
+class UiCompositorControllerParent;
+class WebRenderBridgeParent;
+class WebRenderScrollDataWrapper;
+struct CollectedFrames;
+
+struct ScopedLayerTreeRegistration {
+  // For WebRender
+  ScopedLayerTreeRegistration(LayersId aLayersId,
+                              GeckoContentController* aController);
+  ~ScopedLayerTreeRegistration();
+
+ private:
+  LayersId mLayersId;
+};
+
+class CompositorBridgeParentBase : public PCompositorBridgeParent,
+                                   public HostIPCAllocator,
+                                   public mozilla::ipc::IShmemAllocator {
+  friend class PCompositorBridgeParent;
+
+ public:
+  explicit CompositorBridgeParentBase(CompositorManagerParent* aManager);
+
+  virtual bool SetTestSampleTime(const LayersId& aId, const TimeStamp& aTime) {
+    return true;
+  }
+  virtual void LeaveTestMode(const LayersId& aId) {}
+  enum class TransformsToSkip : uint8_t { NoneOfThem = 0, APZ = 1 };
+  virtual void SetTestAsyncScrollOffset(
+      const LayersId& aLayersId, const ScrollableLayerGuid::ViewID& aScrollId,
+      const CSSPoint& aPoint) = 0;
+  virtual void SetTestAsyncZoom(const LayersId& aLayersId,
+                                const ScrollableLayerGuid::ViewID& aScrollId,
+                                const LayerToParentLayerScale& aZoom) = 0;
+  virtual void FlushApzRepaints(const LayersId& aLayersId) = 0;
+  virtual void GetAPZTestData(const LayersId& aLayersId,
+                              APZTestData* aOutData) {}
+  virtual void GetFrameUniformity(const LayersId& aLayersId,
+                                  FrameUniformityData* data) = 0;
+  virtual void SetConfirmedTargetAPZC(
+      const LayersId& aLayersId, const uint64_t& aInputBlockId,
+      nsTArray<ScrollableLayerGuid>&& aTargets) = 0;
+
+  IShmemAllocator* AsShmemAllocator() override { return this; }
+
+  CompositorBridgeParentBase* AsCompositorBridgeParentBase() override {
+    return this;
+  }
+
+  mozilla::ipc::IPCResult RecvSyncWithCompositor() { return IPC_OK(); }
+
+  mozilla::ipc::IPCResult Recv__delete__() override { return IPC_OK(); }
+
+  virtual void ObserveLayersUpdate(LayersId aLayersId, bool aActive) = 0;
+
+  // HostIPCAllocator
+  base::ProcessId GetChildProcessId() override;
+  dom::ContentParentId GetContentId() override;
+  void NotifyNotUsed(PTextureParent* aTexture,
+                     uint64_t aTransactionId) override;
+  void SendAsyncMessage(
+      const nsTArray<AsyncParentMessageData>& aMessage) override;
+
+  // IShmemAllocator
+  bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+  NS_IMETHOD_(MozExternalRefCountType) AddRef() override {
+    return HostIPCAllocator::AddRef();
+  }
+  NS_IMETHOD_(MozExternalRefCountType) Release() override {
+    return HostIPCAllocator::Release();
+  }
+  virtual bool IsRemote() const { return false; }
+
+  virtual void NotifyMemoryPressure() {}
+  virtual void AccumulateMemoryReport(wr::MemoryReport*) {}
+
+ protected:
+  virtual ~CompositorBridgeParentBase();
+
+  virtual PAPZParent* AllocPAPZParent(const LayersId& layersId) = 0;
+  virtual bool DeallocPAPZParent(PAPZParent* aActor) = 0;
+
+  virtual PAPZCTreeManagerParent* AllocPAPZCTreeManagerParent(
+      const LayersId& layersId) = 0;
+  virtual bool DeallocPAPZCTreeManagerParent(
+      PAPZCTreeManagerParent* aActor) = 0;
+
+  virtual PTextureParent* AllocPTextureParent(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aBackend, const TextureFlags& aTextureFlags,
+      const LayersId& id, const uint64_t& aSerial,
+      const MaybeExternalImageId& aExternalImageId) = 0;
+  virtual bool DeallocPTextureParent(PTextureParent* aActor) = 0;
+
+  virtual PWebRenderBridgeParent* AllocPWebRenderBridgeParent(
+      const PipelineId& pipelineId, const LayoutDeviceIntSize& aSize,
+      const WindowKind& aWindowKind) = 0;
+  virtual bool DeallocPWebRenderBridgeParent(
+      PWebRenderBridgeParent* aActor) = 0;
+
+  virtual PCompositorWidgetParent* AllocPCompositorWidgetParent(
+      const CompositorWidgetInitData& aInitData) = 0;
+  virtual bool DeallocPCompositorWidgetParent(
+      PCompositorWidgetParent* aActor) = 0;
+
+  virtual mozilla::ipc::IPCResult RecvAdoptChild(const LayersId& id) = 0;
+  virtual mozilla::ipc::IPCResult RecvFlushRenderingAsync(
+      const wr::RenderReasons& aReasons) = 0;
+  virtual mozilla::ipc::IPCResult RecvForcePresent(
+      const wr::RenderReasons& aReasons) = 0;
+  virtual mozilla::ipc::IPCResult RecvBeginRecording(
+      const TimeStamp& aRecordingStart, BeginRecordingResolver&& aResolve) = 0;
+  virtual mozilla::ipc::IPCResult RecvEndRecording(
+      EndRecordingResolver&& aResolve) = 0;
+  virtual mozilla::ipc::IPCResult RecvInitialize(
+      const LayersId& rootLayerTreeId) = 0;
+  virtual mozilla::ipc::IPCResult RecvWillClose() = 0;
+  virtual mozilla::ipc::IPCResult RecvPause() = 0;
+  virtual mozilla::ipc::IPCResult RecvRequestFxrOutput() = 0;
+  virtual mozilla::ipc::IPCResult RecvResume() = 0;
+  virtual mozilla::ipc::IPCResult RecvResumeAsync() = 0;
+  virtual mozilla::ipc::IPCResult RecvNotifyChildCreated(
+      const LayersId& id, CompositorOptions* compositorOptions) = 0;
+  virtual mozilla::ipc::IPCResult RecvMapAndNotifyChildCreated(
+      const LayersId& id, const ProcessId& owner,
+      CompositorOptions* compositorOptions) = 0;
+  virtual mozilla::ipc::IPCResult RecvNotifyChildRecreated(
+      const LayersId& id, CompositorOptions* compositorOptions) = 0;
+  virtual mozilla::ipc::IPCResult RecvFlushRendering(
+      const wr::RenderReasons& aReasons) = 0;
+  virtual mozilla::ipc::IPCResult RecvNotifyMemoryPressure() = 0;
+  virtual mozilla::ipc::IPCResult RecvWaitOnTransactionProcessed() = 0;
+  virtual mozilla::ipc::IPCResult RecvStartFrameTimeRecording(
+      const int32_t& bufferSize, uint32_t* startIndex) = 0;
+  virtual mozilla::ipc::IPCResult RecvStopFrameTimeRecording(
+      const uint32_t& startIndex, nsTArray<float>* intervals) = 0;
+  virtual mozilla::ipc::IPCResult RecvCheckContentOnlyTDR(
+      const uint32_t& sequenceNum, bool* isContentOnlyTDR) = 0;
+
+  bool mCanSend;
+
+ protected:
+  RefPtr<CompositorManagerParent> mCompositorManager;
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(
+    CompositorBridgeParentBase::TransformsToSkip)
+
+class CompositorBridgeParent final : public CompositorBridgeParentBase,
+                                     public CompositorController {
+  friend class CompositorThreadHolder;
+  friend class InProcessCompositorSession;
+  friend class gfx::GPUProcessManager;
+  friend class gfx::GPUParent;
+  friend class PCompositorBridgeParent;
+
+ public:
+  NS_IMETHOD_(MozExternalRefCountType) AddRef() override {
+    return CompositorBridgeParentBase::AddRef();
+  }
+  NS_IMETHOD_(MozExternalRefCountType) Release() override {
+    return CompositorBridgeParentBase::Release();
+  }
+
+  explicit CompositorBridgeParent(CompositorManagerParent* aManager,
+                                  CSSToLayoutDeviceScale aScale,
+                                  const TimeDuration& aVsyncRate,
+                                  const CompositorOptions& aOptions,
+                                  bool aUseExternalSurfaceSize,
+                                  const gfx::IntSize& aSurfaceSize,
+                                  uint64_t aInnerWindowId);
+
+  void InitSameProcess(widget::CompositorWidget* aWidget,
+                       const LayersId& aLayerTreeId);
+
+  mozilla::ipc::IPCResult RecvInitialize(
+      const LayersId& aRootLayerTreeId) override;
+  mozilla::ipc::IPCResult RecvWillClose() override;
+  mozilla::ipc::IPCResult RecvPause() override;
+  mozilla::ipc::IPCResult RecvRequestFxrOutput() override;
+  mozilla::ipc::IPCResult RecvResume() override;
+  mozilla::ipc::IPCResult RecvResumeAsync() override;
+  mozilla::ipc::IPCResult RecvNotifyChildCreated(
+      const LayersId& child, CompositorOptions* aOptions) override;
+  mozilla::ipc::IPCResult RecvMapAndNotifyChildCreated(
+      const LayersId& child, const base::ProcessId& pid,
+      CompositorOptions* aOptions) override;
+  mozilla::ipc::IPCResult RecvNotifyChildRecreated(
+      const LayersId& child, CompositorOptions* aOptions) override;
+  mozilla::ipc::IPCResult RecvAdoptChild(const LayersId& child) override;
+  mozilla::ipc::IPCResult RecvFlushRendering(
+      const wr::RenderReasons& aReasons) override;
+  mozilla::ipc::IPCResult RecvFlushRenderingAsync(
+      const wr::RenderReasons& aReasons) override;
+  mozilla::ipc::IPCResult RecvWaitOnTransactionProcessed() override;
+  mozilla::ipc::IPCResult RecvForcePresent(
+      const wr::RenderReasons& aReasons) override;
+
+  mozilla::ipc::IPCResult RecvStartFrameTimeRecording(
+      const int32_t& aBufferSize, uint32_t* aOutStartIndex) override;
+  mozilla::ipc::IPCResult RecvStopFrameTimeRecording(
+      const uint32_t& aStartIndex, nsTArray<float>* intervals) override;
+
+  mozilla::ipc::IPCResult RecvCheckContentOnlyTDR(
+      const uint32_t& sequenceNum, bool* isContentOnlyTDR) override {
+    return IPC_OK();
+  }
+
+  mozilla::ipc::IPCResult RecvNotifyMemoryPressure() override;
+  mozilla::ipc::IPCResult RecvBeginRecording(
+      const TimeStamp& aRecordingStart,
+      BeginRecordingResolver&& aResolve) override;
+  mozilla::ipc::IPCResult RecvEndRecording(
+      EndRecordingResolver&& aResolve) override;
+
+  void NotifyMemoryPressure() override;
+  void AccumulateMemoryReport(wr::MemoryReport*) override;
+
+  void ActorDestroy(ActorDestroyReason why) override;
+
+  bool SetTestSampleTime(const LayersId& aId, const TimeStamp& aTime) override;
+  void LeaveTestMode(const LayersId& aId) override;
+  CompositorAnimationStorage* GetAnimationStorage();
+  using JankedAnimations =
+      std::unordered_map<LayersId, nsTArray<uint64_t>, LayersId::HashFn>;
+  void NotifyJankedAnimations(const JankedAnimations& aJankedAnimations);
+  void SetTestAsyncScrollOffset(const LayersId& aLayersId,
+                                const ScrollableLayerGuid::ViewID& aScrollId,
+                                const CSSPoint& aPoint) override;
+  void SetTestAsyncZoom(const LayersId& aLayersId,
+                        const ScrollableLayerGuid::ViewID& aScrollId,
+                        const LayerToParentLayerScale& aZoom) override;
+  void FlushApzRepaints(const LayersId& aLayersId) override;
+  void GetAPZTestData(const LayersId& aLayersId,
+                      APZTestData* aOutData) override;
+  void GetFrameUniformity(const LayersId& aLayersId,
+                          FrameUniformityData* data) override;
+  void SetConfirmedTargetAPZC(
+      const LayersId& aLayersId, const uint64_t& aInputBlockId,
+      nsTArray<ScrollableLayerGuid>&& aTargets) override;
+  void SetFixedLayerMargins(ScreenIntCoord aTop, ScreenIntCoord aBottom);
+
+  PTextureParent* AllocPTextureParent(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+      const LayersId& aId, const uint64_t& aSerial,
+      const wr::MaybeExternalImageId& aExternalImageId) override;
+  bool DeallocPTextureParent(PTextureParent* actor) override;
+
+  bool IsSameProcess() const override;
+
+  void NotifyWebRenderDisableNativeCompositor();
+
+  void NotifyDidRender(const VsyncId& aCompositeStartId,
+                       TimeStamp& aCompositeStart, TimeStamp& aRenderStart,
+                       TimeStamp& aCompositeEnd,
+                       wr::RendererStats* aStats = nullptr);
+  void NotifyPipelineRendered(const wr::PipelineId& aPipelineId,
+                              const wr::Epoch& aEpoch,
+                              const VsyncId& aCompositeStartId,
+                              TimeStamp& aCompositeStart,
+                              TimeStamp& aRenderStart, TimeStamp& aCompositeEnd,
+                              wr::RendererStats* aStats = nullptr);
+  void NotifyDidSceneBuild(RefPtr<const wr::WebRenderPipelineInfo> aInfo);
+  RefPtr<AsyncImagePipelineManager> GetAsyncImagePipelineManager() const;
+
+  PCompositorWidgetParent* AllocPCompositorWidgetParent(
+      const CompositorWidgetInitData& aInitData) override;
+  bool DeallocPCompositorWidgetParent(PCompositorWidgetParent* aActor) override;
+
+  void ObserveLayersUpdate(LayersId aLayersId, bool aActive) override {}
+
+  /**
+   * This forces the is-first-paint flag to true. This is intended to
+   * be called by the widget code when it loses its viewport information
+   * (or for whatever reason wants to refresh the viewport information).
+   * The information refresh happens because the compositor will call
+   * SetFirstPaintViewport on the next frame of composition.
+   */
+  void ForceIsFirstPaint();
+
+  void NotifyChildCreated(LayersId aChild);
+
+  void AsyncRender();
+
+  // Can be called from any thread
+  void ScheduleRenderOnCompositorThread(wr::RenderReasons aReasons) override;
+
+  void ScheduleComposition(wr::RenderReasons aReasons);
+
+  static void ScheduleForcedComposition(const LayersId& aLayersId,
+                                        wr::RenderReasons aReasons);
+
+  /**
+   * Returns the unique layer tree identifier that corresponds to the root
+   * tree of this compositor.
+   */
+  LayersId RootLayerTreeId();
+
+  /**
+   * Initialize statics.
+   */
+  static void InitializeStatics();
+
+  /**
+   * Notify the compositor for the given layer tree that vsync has occurred.
+   */
+  static void NotifyVsync(const VsyncEvent& aVsync, const LayersId& aLayersId);
+
+  /**
+   * Set aController as the pan/zoom callback for the subtree referred
+   * to by aLayersId.
+   *
+   * Must run on content main thread.
+   */
+  static void SetControllerForLayerTree(LayersId aLayersId,
+                                        GeckoContentController* aController);
+
+  struct LayerTreeState {
+    LayerTreeState();
+    ~LayerTreeState();
+    RefPtr<GeckoContentController> mController;
+    APZCTreeManagerParent* mApzcTreeManagerParent;
+    RefPtr<CompositorBridgeParent> mParent;
+    RefPtr<WebRenderBridgeParent> mWrBridge;
+    // Pointer to the ContentCompositorBridgeParent. Used by APZCs to share
+    // their FrameMetrics with the corresponding child process that holds
+    // the PCompositorBridgeChild
+    ContentCompositorBridgeParent* mContentCompositorBridgeParent;
+
+    CompositorController* GetCompositorController() const;
+    RefPtr<UiCompositorControllerParent> mUiControllerParent;
+  };
+
+  /**
+   * Lookup the indirect shadow tree for |aId| and return it if it
+   * exists.  Otherwise null is returned.  This must only be called on
+   * the compositor thread.
+   */
+  static LayerTreeState* GetIndirectShadowTree(LayersId aId);
+
+  /**
+   * Lookup the indirect shadow tree for |aId|, call the function object and
+   * return true if found. If not found, return false.
+   */
+  static bool CallWithIndirectShadowTree(
+      LayersId aId, const std::function<void(LayerTreeState&)>& aFunc);
+
+  /**
+   * Given the layers id for a content process, get the APZCTreeManagerParent
+   * for the corresponding *root* layers id. That is, the APZCTreeManagerParent,
+   * if one is found, will always be connected to the parent process rather
+   * than a content process. Note that unless the compositor process is
+   * separated this is expected to return null, because if the compositor is
+   * living in the gecko parent process then there is no APZCTreeManagerParent
+   * for the parent process.
+   */
+  static APZCTreeManagerParent* GetApzcTreeManagerParentForRoot(
+      LayersId aContentLayersId);
+  /**
+   * Same as the GetApzcTreeManagerParentForRoot function, but returns
+   * the GeckoContentController for the parent process.
+   */
+  static GeckoContentController* GetGeckoContentControllerForRoot(
+      LayersId aContentLayersId);
+
+  /**
+   * Used by the profiler to denote when a vsync occured
+   */
+  static void PostInsertVsyncProfilerMarker(mozilla::TimeStamp aVsyncTimestamp);
+
+  widget::CompositorWidget* GetWidget() { return mWidget; }
+
+  PAPZCTreeManagerParent* AllocPAPZCTreeManagerParent(
+      const LayersId& aLayersId) override;
+  bool DeallocPAPZCTreeManagerParent(PAPZCTreeManagerParent* aActor) override;
+
+  // Helper method so that we don't have to expose mApzcTreeManager to
+  // ContentCompositorBridgeParent.
+  void AllocateAPZCTreeManagerParent(
+      const StaticMonitorAutoLock& aProofOfLayerTreeStateLock,
+      const LayersId& aLayersId, LayerTreeState& aLayerTreeStateToUpdate);
+
+  PAPZParent* AllocPAPZParent(const LayersId& aLayersId) override;
+  bool DeallocPAPZParent(PAPZParent* aActor) override;
+
+  RefPtr<APZSampler> GetAPZSampler() const;
+  RefPtr<APZUpdater> GetAPZUpdater() const;
+  RefPtr<OMTASampler> GetOMTASampler() const;
+
+  uint64_t GetInnerWindowId() const { return mInnerWindowId; }
+
+  CompositorOptions GetOptions() const { return mOptions; }
+
+  TimeDuration GetVsyncInterval() const {
+    // the variable is called "rate" but really it's an interval
+    return mVsyncRate;
+  }
+
+  PWebRenderBridgeParent* AllocPWebRenderBridgeParent(
+      const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize& aSize,
+      const WindowKind& aWindowKind) override;
+  bool DeallocPWebRenderBridgeParent(PWebRenderBridgeParent* aActor) override;
+  RefPtr<WebRenderBridgeParent> GetWebRenderBridgeParent() const;
+  Maybe<TimeStamp> GetTestingTimeStamp() const;
+
+  static CompositorBridgeParent* GetCompositorBridgeParentFromLayersId(
+      const LayersId& aLayersId);
+  static RefPtr<CompositorBridgeParent> GetCompositorBridgeParentFromWindowId(
+      const wr::WindowId& aWindowId);
+
+  /**
+   * This returns a reference to the IAPZCTreeManager "controller subinterface"
+   * to which pan/zoom-related events can be sent. The controller subinterface
+   * doesn't expose any sampler-thread APZCTreeManager methods.
+   */
+  static already_AddRefed<IAPZCTreeManager> GetAPZCTreeManager(
+      LayersId aLayersId);
+
+  WebRenderBridgeParent* GetWrBridge() { return mWrBridge; }
+
+  void FlushPendingWrTransactionEventsWithWait();
+
+ private:
+  void Initialize();
+
+  /**
+   * Called during destruction in order to release resources as early as
+   * possible.
+   */
+  void StopAndClearResources();
+
+  /**
+   * Release compositor-thread resources referred to by |aID|.
+   *
+   * Must run on the content main thread.
+   */
+  static void DeallocateLayerTreeId(LayersId aId);
+
+  /**
+   * Notify the compositor the quality settings have been updated.
+   */
+  static void UpdateQualitySettings();
+
+  /**
+   * Notify the compositor the debug flags have been updated.
+   */
+  static void UpdateDebugFlags();
+
+  /**
+   * Notify the compositor some webrender parameters have been updated.
+   */
+  static void UpdateWebRenderParameters();
+
+  /**
+   * Notify the compositor some webrender parameters have been updated.
+   */
+  static void UpdateWebRenderBoolParameters();
+
+  /**
+   * Notify the compositor webrender profiler UI string has been updated.
+   */
+  static void UpdateWebRenderProfilerUI();
+
+  static void ResetStable();
+
+  void MaybeDeclareStable();
+
+ protected:
+  // Protected destructor, to discourage deletion outside of Release():
+  virtual ~CompositorBridgeParent();
+
+  void DeferredDestroy();
+
+  void SetEGLSurfaceRect(int x, int y, int width, int height);
+
+ public:
+  void PauseComposition();
+  bool ResumeComposition();
+  bool ResumeCompositionAndResize(int x, int y, int width, int height);
+  bool IsPaused();
+
+  typedef std::map<LayersId, CompositorBridgeParent::LayerTreeState>
+      LayerTreeMap;
+
+  static StaticMonitor sIndirectLayerTreesLock;
+  static LayerTreeMap sIndirectLayerTrees
+      MOZ_GUARDED_BY(sIndirectLayerTreesLock);
+
+ protected:
+  /**
+   * Add a compositor to the global compositor map.
+   */
+  static void AddCompositor(CompositorBridgeParent* compositor, uint64_t* id);
+  /**
+   * Remove a compositor from the global compositor map.
+   */
+  static CompositorBridgeParent* RemoveCompositor(uint64_t id);
+
+  /**
+   * Creates the global compositor map.
+   */
+  static void Setup();
+
+  /**
+   * Remaning cleanups after the compositore thread is gone.
+   */
+  static void FinishShutdown();
+
+  // The indirect layer tree lock must be held before calling this function.
+  // Callback should take (LayerTreeState* aState, const LayersId& aLayersId)
+  template <typename Lambda>
+  inline void ForEachIndirectLayerTree(const Lambda& aCallback);
+
+  // The indirect layer tree lock must be held before calling this function.
+  // Callback should take (LayerTreeState* aState, const LayersId& aLayersId)
+  template <typename Lambda>
+  static inline void ForEachWebRenderBridgeParent(const Lambda& aCallback);
+
+  static bool sStable;
+  static uint32_t sFramesComposited;
+
+  RefPtr<AsyncImagePipelineManager> mAsyncImageManager;
+  RefPtr<WebRenderBridgeParent> mWrBridge;
+  widget::CompositorWidget* mWidget;
+  Maybe<TimeStamp> mTestTime;
+  CSSToLayoutDeviceScale mScale;
+  TimeDuration mVsyncRate;
+
+  bool mPaused;
+  bool mHaveCompositionRecorder;
+  bool mIsForcedFirstPaint;
+
+  bool mUseExternalSurfaceSize;
+  gfx::IntSize mEGLSurfaceSize;
+
+  CompositorOptions mOptions;
+
+  uint64_t mCompositorBridgeID;
+  LayersId mRootLayerTreeID;
+
+  RefPtr<APZCTreeManager> mApzcTreeManager;
+  RefPtr<APZSampler> mApzSampler;
+  RefPtr<APZUpdater> mApzUpdater;
+  RefPtr<OMTASampler> mOMTASampler;
+
+  // Store the inner window id of the browser window, to use it in
+  // profiler markers.
+  uint64_t mInnerWindowId;
+
+  RefPtr<CompositorVsyncScheduler> mCompositorScheduler;
+  // This makes sure the compositorParent is not destroyed before receiving
+  // confirmation that the channel is closed.
+  // mSelfRef is cleared in DeferredDestroy which is scheduled by ActorDestroy.
+  RefPtr<CompositorBridgeParent> mSelfRef;
+  RefPtr<CompositorAnimationStorage> mAnimationStorage;
+
+  DISALLOW_EVIL_CONSTRUCTORS(CompositorBridgeParent);
+};
+
+int32_t RecordContentFrameTime(
+    const VsyncId& aTxnId, const TimeStamp& aVsyncStart,
+    const TimeStamp& aTxnStart, const VsyncId& aCompositeId,
+    const TimeStamp& aCompositeEnd, const TimeDuration& aFullPaintTime,
+    const TimeDuration& aVsyncRate, bool aContainsSVGGroup,
+    bool aRecordUploadStats, wr::RendererStats* aStats = nullptr);
+
+void RecordCompositionPayloadsPresented(
+    const TimeStamp& aCompositionEndTime,
+    const nsTArray<CompositionPayload>& aPayloads);
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CompositorBridgeParent_h
diff --git a/gfx/layers/ipc/CompositorManagerChild.cpp b/gfx/layers/ipc/CompositorManagerChild.cpp
new file mode 100644
index 0000000000..0e553745d3
--- /dev/null
+++ b/gfx/layers/ipc/CompositorManagerChild.cpp
@@ -0,0 +1,257 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/CompositorManagerChild.h"
+
+#include "mozilla/StaticPrefs_layers.h"
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/dom/ContentChild.h"  // for ContentChild
+#include "mozilla/dom/BrowserChild.h"  // for BrowserChild
+#include "mozilla/ipc/Endpoint.h"
+#include "VsyncSource.h"
+
+namespace mozilla {
+namespace layers {
+
+using gfx::GPUProcessManager;
+
+StaticRefPtr<CompositorManagerChild> CompositorManagerChild::sInstance;
+Atomic<base::ProcessId> CompositorManagerChild::sOtherPid(0);
+
+/* static */
+bool CompositorManagerChild::IsInitialized(uint64_t aProcessToken) {
+  MOZ_ASSERT(NS_IsMainThread());
+  return sInstance && sInstance->CanSend() &&
+         sInstance->mProcessToken == aProcessToken;
+}
+
+/* static */
+void CompositorManagerChild::InitSameProcess(uint32_t aNamespace,
+                                             uint64_t aProcessToken) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (NS_WARN_IF(IsInitialized(aProcessToken))) {
+    MOZ_ASSERT_UNREACHABLE("Already initialized same process");
+    return;
+  }
+
+  RefPtr<CompositorManagerParent> parent =
+      CompositorManagerParent::CreateSameProcess(aNamespace);
+  RefPtr<CompositorManagerChild> child =
+      new CompositorManagerChild(parent, aProcessToken, aNamespace);
+  if (NS_WARN_IF(!child->CanSend())) {
+    MOZ_DIAGNOSTIC_ASSERT(false, "Failed to open same process protocol");
+    return;
+  }
+
+  parent->BindComplete(/* aIsRoot */ true);
+  sInstance = std::move(child);
+  sOtherPid = sInstance->OtherPid();
+}
+
+/* static */
+bool CompositorManagerChild::Init(Endpoint<PCompositorManagerChild>&& aEndpoint,
+                                  uint32_t aNamespace,
+                                  uint64_t aProcessToken /* = 0 */) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (sInstance) {
+    MOZ_ASSERT(sInstance->mNamespace != aNamespace);
+  }
+
+  sInstance = new CompositorManagerChild(std::move(aEndpoint), aProcessToken,
+                                         aNamespace);
+  sOtherPid = sInstance->OtherPid();
+  return sInstance->CanSend();
+}
+
+/* static */
+void CompositorManagerChild::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+  CompositorBridgeChild::ShutDown();
+
+  if (!sInstance) {
+    return;
+  }
+
+  sInstance->Close();
+  sInstance = nullptr;
+  sOtherPid = 0;
+}
+
+/* static */
+void CompositorManagerChild::OnGPUProcessLost(uint64_t aProcessToken) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Since GPUChild and CompositorManagerChild will race on ActorDestroy, we
+  // cannot know if the CompositorManagerChild is about to be released but has
+  // yet to be. As such, we want to pre-emptively set mCanSend to false.
+  if (sInstance && sInstance->mProcessToken == aProcessToken) {
+    sInstance->mCanSend = false;
+    sOtherPid = 0;
+  }
+}
+
+/* static */
+bool CompositorManagerChild::CreateContentCompositorBridge(
+    uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (NS_WARN_IF(!sInstance || !sInstance->CanSend())) {
+    return false;
+  }
+
+  CompositorBridgeOptions options = ContentCompositorOptions();
+
+  RefPtr<CompositorBridgeChild> bridge = new CompositorBridgeChild(sInstance);
+  if (NS_WARN_IF(
+          !sInstance->SendPCompositorBridgeConstructor(bridge, options))) {
+    return false;
+  }
+
+  bridge->InitForContent(aNamespace);
+  return true;
+}
+
+/* static */
+already_AddRefed<CompositorBridgeChild>
+CompositorManagerChild::CreateWidgetCompositorBridge(
+    uint64_t aProcessToken, WebRenderLayerManager* aLayerManager,
+    uint32_t aNamespace, CSSToLayoutDeviceScale aScale,
+    const CompositorOptions& aOptions, bool aUseExternalSurfaceSize,
+    const gfx::IntSize& aSurfaceSize, uint64_t aInnerWindowId) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  if (NS_WARN_IF(!sInstance || !sInstance->CanSend())) {
+    return nullptr;
+  }
+
+  TimeDuration vsyncRate =
+      gfxPlatform::GetPlatform()->GetGlobalVsyncDispatcher()->GetVsyncRate();
+
+  CompositorBridgeOptions options = WidgetCompositorOptions(
+      aScale, vsyncRate, aOptions, aUseExternalSurfaceSize, aSurfaceSize,
+      aInnerWindowId);
+
+  RefPtr<CompositorBridgeChild> bridge = new CompositorBridgeChild(sInstance);
+  if (NS_WARN_IF(
+          !sInstance->SendPCompositorBridgeConstructor(bridge, options))) {
+    return nullptr;
+  }
+
+  bridge->InitForWidget(aProcessToken, aLayerManager, aNamespace);
+  return bridge.forget();
+}
+
+/* static */
+already_AddRefed<CompositorBridgeChild>
+CompositorManagerChild::CreateSameProcessWidgetCompositorBridge(
+    WebRenderLayerManager* aLayerManager, uint32_t aNamespace) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  if (NS_WARN_IF(!sInstance || !sInstance->CanSend())) {
+    return nullptr;
+  }
+
+  CompositorBridgeOptions options = SameProcessWidgetCompositorOptions();
+
+  RefPtr<CompositorBridgeChild> bridge = new CompositorBridgeChild(sInstance);
+  if (NS_WARN_IF(
+          !sInstance->SendPCompositorBridgeConstructor(bridge, options))) {
+    return nullptr;
+  }
+
+  bridge->InitForWidget(1, aLayerManager, aNamespace);
+  return bridge.forget();
+}
+
+CompositorManagerChild::CompositorManagerChild(CompositorManagerParent* aParent,
+                                               uint64_t aProcessToken,
+                                               uint32_t aNamespace)
+    : mProcessToken(aProcessToken),
+      mNamespace(aNamespace),
+      mResourceId(0),
+      mCanSend(false),
+      mSameProcess(true),
+      mFwdTransactionCounter(this) {
+  MOZ_ASSERT(aParent);
+
+  SetOtherProcessId(base::GetCurrentProcId());
+  if (NS_WARN_IF(!Open(aParent, CompositorThread(), ipc::ChildSide))) {
+    return;
+  }
+
+  mCanSend = true;
+  SetReplyTimeout();
+}
+
+CompositorManagerChild::CompositorManagerChild(
+    Endpoint<PCompositorManagerChild>&& aEndpoint, uint64_t aProcessToken,
+    uint32_t aNamespace)
+    : mProcessToken(aProcessToken),
+      mNamespace(aNamespace),
+      mResourceId(0),
+      mCanSend(false),
+      mSameProcess(false),
+      mFwdTransactionCounter(this) {
+  if (NS_WARN_IF(!aEndpoint.Bind(this))) {
+    return;
+  }
+
+  mCanSend = true;
+  SetReplyTimeout();
+}
+
+void CompositorManagerChild::ActorDestroy(ActorDestroyReason aReason) {
+  mCanSend = false;
+  if (sInstance == this) {
+    sInstance = nullptr;
+  }
+}
+
+void CompositorManagerChild::HandleFatalError(const char* aMsg) {
+  dom::ContentChild::FatalErrorIfNotUsingGPUProcess(aMsg, OtherPid());
+}
+
+void CompositorManagerChild::ProcessingError(Result aCode,
+                                             const char* aReason) {
+  if (aCode != MsgDropped) {
+    gfxDevCrash(gfx::LogReason::ProcessingError)
+        << "Processing error in CompositorBridgeChild: " << int(aCode);
+  }
+}
+
+void CompositorManagerChild::SetReplyTimeout() {
+#ifndef DEBUG
+  // Add a timeout for release builds to kill GPU process when it hangs.
+  if (XRE_IsParentProcess() && GPUProcessManager::Get()->GetGPUChild()) {
+    int32_t timeout =
+        StaticPrefs::layers_gpu_process_ipc_reply_timeout_ms_AtStartup();
+    SetReplyTimeoutMs(timeout);
+  }
+#endif
+}
+
+bool CompositorManagerChild::ShouldContinueFromReplyTimeout() {
+  if (XRE_IsParentProcess()) {
+    gfxCriticalNote << "Killing GPU process due to IPC reply timeout";
+    MOZ_DIAGNOSTIC_ASSERT(GPUProcessManager::Get()->GetGPUChild());
+    GPUProcessManager::Get()->KillProcess();
+  }
+  return false;
+}
+
+mozilla::ipc::IPCResult CompositorManagerChild::RecvNotifyWebRenderError(
+    const WebRenderError&& aError) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  GPUProcessManager::Get()->NotifyWebRenderError(aError);
+  return IPC_OK();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositorManagerChild.h b/gfx/layers/ipc/CompositorManagerChild.h
new file mode 100644
index 0000000000..072b0d028e
--- /dev/null
+++ b/gfx/layers/ipc/CompositorManagerChild.h
@@ -0,0 +1,125 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_COMPOSITORMANAGERCHILD_H
+#define MOZILLA_GFX_COMPOSITORMANAGERCHILD_H
+
+#include <stddef.h>  // for size_t
+#include <stdint.h>  // for uint32_t, uint64_t
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"                    // for override
+#include "mozilla/RefPtr.h"                        // for already_AddRefed
+#include "mozilla/StaticPtr.h"                     // for StaticRefPtr
+#include "mozilla/layers/CompositableForwarder.h"  // for FwdTransactionCounter
+#include "mozilla/layers/PCompositorManagerChild.h"
+
+namespace mozilla {
+namespace layers {
+
+class CompositorBridgeChild;
+class CompositorManagerParent;
+class WebRenderLayerManager;
+
+class CompositorManagerChild : public PCompositorManagerChild {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorManagerChild, override)
+
+ public:
+  static bool IsInitialized(uint64_t aProcessToken);
+  static void InitSameProcess(uint32_t aNamespace, uint64_t aProcessToken);
+  static bool Init(Endpoint<PCompositorManagerChild>&& aEndpoint,
+                   uint32_t aNamespace, uint64_t aProcessToken = 0);
+  static void Shutdown();
+  static void OnGPUProcessLost(uint64_t aProcessToken);
+
+  static bool CreateContentCompositorBridge(uint32_t aNamespace);
+
+  static already_AddRefed<CompositorBridgeChild> CreateWidgetCompositorBridge(
+      uint64_t aProcessToken, WebRenderLayerManager* aLayerManager,
+      uint32_t aNamespace, CSSToLayoutDeviceScale aScale,
+      const CompositorOptions& aOptions, bool aUseExternalSurfaceSize,
+      const gfx::IntSize& aSurfaceSize, uint64_t aInnerWindowId);
+
+  static already_AddRefed<CompositorBridgeChild>
+  CreateSameProcessWidgetCompositorBridge(WebRenderLayerManager* aLayerManager,
+                                          uint32_t aNamespace);
+
+  static CompositorManagerChild* GetInstance() {
+    MOZ_ASSERT(NS_IsMainThread());
+    return sInstance;
+  }
+
+  // Threadsafe way to get the compositor process ID.
+  static base::ProcessId GetOtherPid() { return sOtherPid; }
+
+  bool CanSend() const {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mCanSend;
+  }
+
+  bool SameProcess() const {
+    MOZ_ASSERT(NS_IsMainThread());
+    return mSameProcess;
+  }
+
+  uint32_t GetNextResourceId() {
+    MOZ_ASSERT(NS_IsMainThread());
+    return ++mResourceId;
+  }
+
+  uint32_t GetNamespace() const { return mNamespace; }
+
+  bool OwnsExternalImageId(const wr::ExternalImageId& aId) const {
+    return mNamespace == static_cast<uint32_t>(wr::AsUint64(aId) >> 32);
+  }
+
+  wr::ExternalImageId GetNextExternalImageId() {
+    uint64_t id = GetNextResourceId();
+    MOZ_RELEASE_ASSERT(id != 0);
+    id |= (static_cast<uint64_t>(mNamespace) << 32);
+    return wr::ToExternalImageId(id);
+  }
+
+  void ActorDestroy(ActorDestroyReason aReason) override;
+
+  void HandleFatalError(const char* aMsg) override;
+
+  void ProcessingError(Result aCode, const char* aReason) override;
+
+  bool ShouldContinueFromReplyTimeout() override;
+
+  mozilla::ipc::IPCResult RecvNotifyWebRenderError(
+      const WebRenderError&& aError);
+
+  FwdTransactionCounter& GetFwdTransactionCounter() {
+    return mFwdTransactionCounter;
+  }
+
+ private:
+  static StaticRefPtr<CompositorManagerChild> sInstance;
+  static Atomic<base::ProcessId> sOtherPid;
+
+  CompositorManagerChild(CompositorManagerParent* aParent,
+                         uint64_t aProcessToken, uint32_t aNamespace);
+
+  CompositorManagerChild(Endpoint<PCompositorManagerChild>&& aEndpoint,
+                         uint64_t aProcessToken, uint32_t aNamespace);
+
+  virtual ~CompositorManagerChild() = default;
+
+  void SetReplyTimeout();
+
+  uint64_t mProcessToken;
+  uint32_t mNamespace;
+  uint32_t mResourceId;
+  bool mCanSend;
+  bool mSameProcess;
+  FwdTransactionCounter mFwdTransactionCounter;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositorManagerParent.cpp b/gfx/layers/ipc/CompositorManagerParent.cpp
new file mode 100644
index 0000000000..29d9699033
--- /dev/null
+++ b/gfx/layers/ipc/CompositorManagerParent.cpp
@@ -0,0 +1,396 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/gfx/GPUParent.h"
+#include "mozilla/gfx/CanvasManagerParent.h"
+#include "mozilla/webrender/RenderThread.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/ContentCompositorBridgeParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/RemoteTextureMap.h"
+#include "mozilla/layers/SharedSurfacesParent.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "gfxPlatform.h"
+#include "VsyncSource.h"
+
+namespace mozilla {
+namespace layers {
+
+StaticMonitor CompositorManagerParent::sMonitor;
+StaticRefPtr<CompositorManagerParent> CompositorManagerParent::sInstance;
+CompositorManagerParent::ManagerMap CompositorManagerParent::sManagers;
+
+/* static */
+already_AddRefed<CompositorManagerParent>
+CompositorManagerParent::CreateSameProcess(uint32_t aNamespace) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  StaticMonitorAutoLock lock(sMonitor);
+
+  // We are creating a manager for the UI process, inside the combined GPU/UI
+  // process. It is created more-or-less the same but we retain a reference to
+  // the parent to access state.
+  if (NS_WARN_IF(sInstance)) {
+    MOZ_ASSERT_UNREACHABLE("Already initialized");
+    return nullptr;
+  }
+
+  // The child is responsible for setting up the IPC channel in the same
+  // process case because if we open from the child perspective, we can do it
+  // on the main thread and complete before we return the manager handles.
+  RefPtr<CompositorManagerParent> parent =
+      new CompositorManagerParent(dom::ContentParentId(), aNamespace);
+  parent->SetOtherProcessId(base::GetCurrentProcId());
+  return parent.forget();
+}
+
+/* static */
+bool CompositorManagerParent::Create(
+    Endpoint<PCompositorManagerParent>&& aEndpoint,
+    dom::ContentParentId aChildId, uint32_t aNamespace, bool aIsRoot) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // We are creating a manager for the another process, inside the GPU process
+  // (or UI process if it subsumbed the GPU process).
+  MOZ_ASSERT(aEndpoint.OtherPid() != base::GetCurrentProcId());
+
+  if (!CompositorThreadHolder::IsActive()) {
+    return false;
+  }
+
+  RefPtr<CompositorManagerParent> bridge =
+      new CompositorManagerParent(aChildId, aNamespace);
+
+  RefPtr<Runnable> runnable =
+      NewRunnableMethod<Endpoint<PCompositorManagerParent>&&, bool>(
+          "CompositorManagerParent::Bind", bridge,
+          &CompositorManagerParent::Bind, std::move(aEndpoint), aIsRoot);
+  CompositorThread()->Dispatch(runnable.forget());
+  return true;
+}
+
+/* static */
+already_AddRefed<CompositorBridgeParent>
+CompositorManagerParent::CreateSameProcessWidgetCompositorBridge(
+    CSSToLayoutDeviceScale aScale, const CompositorOptions& aOptions,
+    bool aUseExternalSurfaceSize, const gfx::IntSize& aSurfaceSize,
+    uint64_t aInnerWindowId) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // When we are in a combined UI / GPU process, InProcessCompositorSession
+  // requires both the parent and child PCompositorBridge actors for its own
+  // construction, which is done on the main thread. Normally
+  // CompositorBridgeParent is created on the compositor thread via the IPDL
+  // plumbing (CompositorManagerParent::AllocPCompositorBridgeParent). Thus to
+  // actually get a reference to the parent, we would need to block on the
+  // compositor thread until it handles our constructor message. Because only
+  // one one IPDL constructor is permitted per parent and child protocol, we
+  // cannot make the normal case async and this case sync. Instead what we do
+  // is leave the constructor async (a boon to the content process setup) and
+  // create the parent ahead of time. It will pull the preinitialized parent
+  // from the queue when it receives the message and give that to IPDL.
+
+  // Note that the static mutex not only is used to protect sInstance, but also
+  // mPendingCompositorBridges.
+  StaticMonitorAutoLock lock(sMonitor);
+  if (NS_WARN_IF(!sInstance)) {
+    return nullptr;
+  }
+
+  TimeDuration vsyncRate =
+      gfxPlatform::GetPlatform()->GetGlobalVsyncDispatcher()->GetVsyncRate();
+
+  RefPtr<CompositorBridgeParent> bridge = new CompositorBridgeParent(
+      sInstance, aScale, vsyncRate, aOptions, aUseExternalSurfaceSize,
+      aSurfaceSize, aInnerWindowId);
+
+  sInstance->mPendingCompositorBridges.AppendElement(bridge);
+  return bridge.forget();
+}
+
+CompositorManagerParent::CompositorManagerParent(
+    dom::ContentParentId aContentId, uint32_t aNamespace)
+    : mCompositorThreadHolder(CompositorThreadHolder::GetSingleton()),
+      mSharedSurfacesHolder(MakeRefPtr<SharedSurfacesHolder>(aNamespace)),
+      mContentId(aContentId),
+      mNamespace(aNamespace) {}
+
+CompositorManagerParent::~CompositorManagerParent() = default;
+
+void CompositorManagerParent::Bind(
+    Endpoint<PCompositorManagerParent>&& aEndpoint, bool aIsRoot) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (NS_WARN_IF(!aEndpoint.Bind(this))) {
+    return;
+  }
+
+  BindComplete(aIsRoot);
+}
+
+void CompositorManagerParent::BindComplete(bool aIsRoot) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread() ||
+             NS_IsMainThread());
+
+  StaticMonitorAutoLock lock(sMonitor);
+  if (aIsRoot) {
+    MOZ_ASSERT(!sInstance);
+    sInstance = this;
+  }
+
+  MOZ_RELEASE_ASSERT(sManagers.try_emplace(mNamespace, this).second);
+}
+
+void CompositorManagerParent::ActorDestroy(ActorDestroyReason aReason) {
+  GetCurrentSerialEventTarget()->Dispatch(
+      NewRunnableMethod("layers::CompositorManagerParent::DeferredDestroy",
+                        this, &CompositorManagerParent::DeferredDestroy));
+
+  if (mRemoteTextureTxnScheduler) {
+    mRemoteTextureTxnScheduler = nullptr;
+  }
+
+  StaticMonitorAutoLock lock(sMonitor);
+  if (sInstance == this) {
+    sInstance = nullptr;
+  }
+
+  MOZ_RELEASE_ASSERT(sManagers.erase(mNamespace) > 0);
+  sMonitor.NotifyAll();
+}
+
+void CompositorManagerParent::DeferredDestroy() {
+  mCompositorThreadHolder = nullptr;
+}
+
+/* static */
+void CompositorManagerParent::ShutdownInternal() {
+  nsTArray<RefPtr<CompositorManagerParent>> actors;
+
+  // We move here because we may attempt to acquire the same lock during the
+  // destroy to remove the reference in sManagers.
+  {
+    StaticMonitorAutoLock lock(sMonitor);
+    actors.SetCapacity(sManagers.size());
+    for (auto& i : sManagers) {
+      actors.AppendElement(i.second);
+    }
+  }
+
+  for (auto& actor : actors) {
+    actor->Close();
+  }
+}
+
+/* static */
+void CompositorManagerParent::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  CompositorThread()->Dispatch(NS_NewRunnableFunction(
+      "layers::CompositorManagerParent::Shutdown",
+      []() -> void { CompositorManagerParent::ShutdownInternal(); }));
+}
+
+/* static */ void CompositorManagerParent::WaitForSharedSurface(
+    const wr::ExternalImageId& aId) {
+  uint32_t extNamespace = static_cast<uint32_t>(wr::AsUint64(aId) >> 32);
+  uint32_t resourceId = static_cast<uint32_t>(wr::AsUint64(aId));
+
+  StaticMonitorAutoLock lock(sMonitor);
+
+  while (true) {
+    const auto i = sManagers.find(extNamespace);
+    if (NS_WARN_IF(i == sManagers.end())) {
+      break;
+    }
+
+    // We know that when the resource ID is allocated, we either fail to have
+    // shared the surface with the compositor process, and so we don't use the
+    // external image ID, or we have queued an IPDL message over the
+    // corresponding CompositorManagerParent object to map that surface into
+    // memory. They are dispatched in order, so we can safely wait until either
+    // the actor is closed, or the last seen resource ID reaches the target.
+    if (i->second->mLastSharedSurfaceResourceId >= resourceId) {
+      break;
+    }
+
+    lock.Wait();
+  }
+}
+
+already_AddRefed<PCompositorBridgeParent>
+CompositorManagerParent::AllocPCompositorBridgeParent(
+    const CompositorBridgeOptions& aOpt) {
+  switch (aOpt.type()) {
+    case CompositorBridgeOptions::TContentCompositorOptions: {
+      RefPtr<ContentCompositorBridgeParent> bridge =
+          new ContentCompositorBridgeParent(this);
+      return bridge.forget();
+    }
+    case CompositorBridgeOptions::TWidgetCompositorOptions: {
+      // Only the UI process is allowed to create widget compositors in the
+      // compositor process.
+      gfx::GPUParent* gpu = gfx::GPUParent::GetSingleton();
+      if (NS_WARN_IF(!gpu || OtherPid() != gpu->OtherPid())) {
+        MOZ_ASSERT_UNREACHABLE("Child cannot create widget compositor!");
+        break;
+      }
+
+      const WidgetCompositorOptions& opt = aOpt.get_WidgetCompositorOptions();
+      RefPtr<CompositorBridgeParent> bridge = new CompositorBridgeParent(
+          this, opt.scale(), opt.vsyncRate(), opt.options(),
+          opt.useExternalSurfaceSize(), opt.surfaceSize(), opt.innerWindowId());
+      return bridge.forget();
+    }
+    case CompositorBridgeOptions::TSameProcessWidgetCompositorOptions: {
+      // If the GPU and UI process are combined, we actually already created the
+      // CompositorBridgeParent, so we need to reuse that to inject it into the
+      // IPDL framework.
+      if (NS_WARN_IF(OtherPid() != base::GetCurrentProcId())) {
+        MOZ_ASSERT_UNREACHABLE("Child cannot create same process compositor!");
+        break;
+      }
+
+      // Note that the static mutex not only is used to protect sInstance, but
+      // also mPendingCompositorBridges.
+      StaticMonitorAutoLock lock(sMonitor);
+      if (mPendingCompositorBridges.IsEmpty()) {
+        break;
+      }
+
+      RefPtr<CompositorBridgeParent> bridge = mPendingCompositorBridges[0];
+      mPendingCompositorBridges.RemoveElementAt(0);
+      return bridge.forget();
+    }
+    default:
+      break;
+  }
+
+  return nullptr;
+}
+
+/* static */ void CompositorManagerParent::AddSharedSurface(
+    const wr::ExternalImageId& aId, gfx::SourceSurfaceSharedData* aSurface) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  StaticMonitorAutoLock lock(sMonitor);
+  if (NS_WARN_IF(!sInstance)) {
+    return;
+  }
+
+  if (NS_WARN_IF(!sInstance->OwnsExternalImageId(aId))) {
+    MOZ_ASSERT_UNREACHABLE("Wrong namespace?");
+    return;
+  }
+
+  SharedSurfacesParent::AddSameProcess(aId, aSurface);
+
+  uint32_t resourceId = static_cast<uint32_t>(wr::AsUint64(aId));
+  MOZ_RELEASE_ASSERT(sInstance->mLastSharedSurfaceResourceId < resourceId);
+  sInstance->mLastSharedSurfaceResourceId = resourceId;
+  sMonitor.NotifyAll();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvAddSharedSurface(
+    const wr::ExternalImageId& aId, SurfaceDescriptorShared&& aDesc) {
+  if (NS_WARN_IF(!OwnsExternalImageId(aId))) {
+    MOZ_ASSERT_UNREACHABLE("Wrong namespace?");
+    return IPC_OK();
+  }
+
+  SharedSurfacesParent::Add(aId, std::move(aDesc), OtherPid());
+
+  StaticMonitorAutoLock lock(sMonitor);
+  uint32_t resourceId = static_cast<uint32_t>(wr::AsUint64(aId));
+  MOZ_RELEASE_ASSERT(mLastSharedSurfaceResourceId < resourceId);
+  mLastSharedSurfaceResourceId = resourceId;
+  sMonitor.NotifyAll();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvRemoveSharedSurface(
+    const wr::ExternalImageId& aId) {
+  if (NS_WARN_IF(!OwnsExternalImageId(aId))) {
+    MOZ_ASSERT_UNREACHABLE("Wrong namespace?");
+    return IPC_OK();
+  }
+
+  SharedSurfacesParent::Remove(aId);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvReportSharedSurfacesMemory(
+    ReportSharedSurfacesMemoryResolver&& aResolver) {
+  SharedSurfacesMemoryReport report;
+  SharedSurfacesParent::AccumulateMemoryReport(mNamespace, report);
+  aResolver(std::move(report));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvNotifyMemoryPressure() {
+  nsTArray<PCompositorBridgeParent*> compositorBridges;
+  ManagedPCompositorBridgeParent(compositorBridges);
+  for (auto bridge : compositorBridges) {
+    static_cast<CompositorBridgeParentBase*>(bridge)->NotifyMemoryPressure();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvReportMemory(
+    ReportMemoryResolver&& aResolver) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MemoryReport aggregate;
+  PodZero(&aggregate);
+
+  // Accumulate RenderBackend usage.
+  nsTArray<PCompositorBridgeParent*> compositorBridges;
+  ManagedPCompositorBridgeParent(compositorBridges);
+  for (auto bridge : compositorBridges) {
+    static_cast<CompositorBridgeParentBase*>(bridge)->AccumulateMemoryReport(
+        &aggregate);
+  }
+
+  // Accumulate Renderer usage asynchronously, and resolve.
+  //
+  // Note that the IPDL machinery requires aResolver to be called on this
+  // thread, so we can't just pass it over to the renderer thread. We use
+  // an intermediate MozPromise instead.
+  wr::RenderThread::AccumulateMemoryReport(aggregate)->Then(
+      CompositorThread(), __func__,
+      [resolver = std::move(aResolver)](MemoryReport aReport) {
+        resolver(aReport);
+      },
+      [](bool) {
+        MOZ_ASSERT_UNREACHABLE("MemoryReport promises are never rejected");
+      });
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult CompositorManagerParent::RecvInitCanvasManager(
+    Endpoint<PCanvasManagerParent>&& aEndpoint) {
+  gfx::CanvasManagerParent::Init(std::move(aEndpoint), mSharedSurfacesHolder,
+                                 mContentId);
+  mRemoteTextureTxnScheduler = RemoteTextureTxnScheduler::Create(this);
+  return IPC_OK();
+}
+
+/* static */
+void CompositorManagerParent::NotifyWebRenderError(wr::WebRenderError aError) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  StaticMonitorAutoLock lock(sMonitor);
+  if (NS_WARN_IF(!sInstance)) {
+    return;
+  }
+  Unused << sInstance->SendNotifyWebRenderError(aError);
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositorManagerParent.h b/gfx/layers/ipc/CompositorManagerParent.h
new file mode 100644
index 0000000000..17eeb61c8c
--- /dev/null
+++ b/gfx/layers/ipc/CompositorManagerParent.h
@@ -0,0 +1,114 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_COMPOSITORMANAGERPARENT_H
+#define MOZILLA_GFX_COMPOSITORMANAGERPARENT_H
+
+#include <map>
+#include <stdint.h>                 // for uint32_t
+#include "mozilla/Attributes.h"     // for override
+#include "mozilla/StaticPtr.h"      // for StaticRefPtr
+#include "mozilla/StaticMonitor.h"  // for StaticMonitor
+#include "mozilla/RefPtr.h"         // for already_AddRefed
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/layers/PCompositorManagerParent.h"
+#include "nsTArray.h"  // for AutoTArray
+
+namespace mozilla {
+
+namespace gfx {
+class SourceSurfaceSharedData;
+}
+
+namespace layers {
+
+class CompositorBridgeParent;
+class CompositorThreadHolder;
+class RemoteTextureTxnScheduler;
+class SharedSurfacesHolder;
+
+class CompositorManagerParent final : public PCompositorManagerParent {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorManagerParent, final)
+
+ public:
+  static already_AddRefed<CompositorManagerParent> CreateSameProcess(
+      uint32_t aNamespace);
+  static bool Create(Endpoint<PCompositorManagerParent>&& aEndpoint,
+                     dom::ContentParentId aContentId, uint32_t aNamespace,
+                     bool aIsRoot);
+  static void Shutdown();
+
+  static already_AddRefed<CompositorBridgeParent>
+  CreateSameProcessWidgetCompositorBridge(CSSToLayoutDeviceScale aScale,
+                                          const CompositorOptions& aOptions,
+                                          bool aUseExternalSurfaceSize,
+                                          const gfx::IntSize& aSurfaceSize,
+                                          uint64_t aInnerWindowId);
+
+  static void WaitForSharedSurface(const wr::ExternalImageId& aId);
+
+  static void AddSharedSurface(const wr::ExternalImageId& aId,
+                               gfx::SourceSurfaceSharedData* aSurface);
+
+  mozilla::ipc::IPCResult RecvAddSharedSurface(const wr::ExternalImageId& aId,
+                                               SurfaceDescriptorShared&& aDesc);
+  mozilla::ipc::IPCResult RecvRemoveSharedSurface(
+      const wr::ExternalImageId& aId);
+  mozilla::ipc::IPCResult RecvReportSharedSurfacesMemory(
+      ReportSharedSurfacesMemoryResolver&&);
+
+  mozilla::ipc::IPCResult RecvNotifyMemoryPressure();
+
+  mozilla::ipc::IPCResult RecvReportMemory(ReportMemoryResolver&&);
+
+  mozilla::ipc::IPCResult RecvInitCanvasManager(
+      Endpoint<PCanvasManagerParent>&&);
+
+  void BindComplete(bool aIsRoot);
+  void ActorDestroy(ActorDestroyReason aReason) override;
+
+  already_AddRefed<PCompositorBridgeParent> AllocPCompositorBridgeParent(
+      const CompositorBridgeOptions& aOpt);
+
+  static void NotifyWebRenderError(wr::WebRenderError aError);
+
+  const dom::ContentParentId& GetContentId() const { return mContentId; }
+
+  bool OwnsExternalImageId(const wr::ExternalImageId& aId) const {
+    return mNamespace == static_cast<uint32_t>(wr::AsUint64(aId) >> 32);
+  }
+
+ private:
+  static StaticMonitor sMonitor;
+  static StaticRefPtr<CompositorManagerParent> sInstance
+      MOZ_GUARDED_BY(sMonitor);
+
+  // Indexed by namespace.
+  using ManagerMap = std::map<uint32_t, CompositorManagerParent*>;
+  static ManagerMap sManagers MOZ_GUARDED_BY(sMonitor);
+
+  static void ShutdownInternal();
+
+  CompositorManagerParent(dom::ContentParentId aContentId, uint32_t aNamespace);
+  virtual ~CompositorManagerParent();
+
+  void Bind(Endpoint<PCompositorManagerParent>&& aEndpoint, bool aIsRoot);
+
+  void DeferredDestroy();
+
+  RefPtr<CompositorThreadHolder> mCompositorThreadHolder;
+  RefPtr<SharedSurfacesHolder> mSharedSurfacesHolder;
+  AutoTArray<RefPtr<CompositorBridgeParent>, 1> mPendingCompositorBridges;
+  const dom::ContentParentId mContentId;
+  const uint32_t mNamespace;
+  uint32_t mLastSharedSurfaceResourceId MOZ_GUARDED_BY(sMonitor) = 0;
+  RefPtr<RemoteTextureTxnScheduler> mRemoteTextureTxnScheduler;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/CompositorThread.cpp b/gfx/layers/ipc/CompositorThread.cpp
new file mode 100644
index 0000000000..65fbdc66f1
--- /dev/null
+++ b/gfx/layers/ipc/CompositorThread.cpp
@@ -0,0 +1,195 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "CompositorThread.h"
+
+#include "CompositorBridgeParent.h"
+#include "gfxGradientCache.h"
+#include "MainThreadUtils.h"
+#include "VRManagerParent.h"
+#include "mozilla/BackgroundHangMonitor.h"
+#include "mozilla/SpinEventLoopUntil.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/layers/ImageBridgeParent.h"
+#include "mozilla/layers/VideoBridgeParent.h"
+#include "mozilla/media/MediaSystemResourceService.h"
+#include "nsThread.h"
+#include "nsThreadUtils.h"
+
+namespace mozilla {
+namespace layers {
+
+static StaticRefPtr<CompositorThreadHolder> sCompositorThreadHolder;
+static Atomic<bool> sFinishedCompositorShutDown(false);
+static mozilla::BackgroundHangMonitor* sBackgroundHangMonitor;
+static ProfilerThreadId sProfilerThreadId;
+
+nsIThread* CompositorThread() {
+  return sCompositorThreadHolder
+             ? sCompositorThreadHolder->GetCompositorThread()
+             : nullptr;
+}
+
+CompositorThreadHolder* CompositorThreadHolder::GetSingleton() {
+  return sCompositorThreadHolder;
+}
+
+CompositorThreadHolder::CompositorThreadHolder()
+    : mCompositorThread(CreateCompositorThread()) {
+  MOZ_ASSERT(NS_IsMainThread());
+}
+
+CompositorThreadHolder::~CompositorThreadHolder() {
+  sFinishedCompositorShutDown = true;
+}
+
+/* static */ already_AddRefed<nsIThread>
+CompositorThreadHolder::CreateCompositorThread() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  MOZ_ASSERT(!sCompositorThreadHolder,
+             "The compositor thread has already been started!");
+
+  // When the CanvasRenderer thread is disabled, WebGL may be handled on this
+  // thread, requiring a bigger stack size. See: CanvasManagerParent::Init
+  //
+  // This is 4M, which is higher than the default 256K.
+  // Increased with bug 1753349 to accommodate the `chromium/5359` branch of
+  // ANGLE, which has large peak stack usage for some pathological shader
+  // compilations.
+  //
+  // Previously increased to 512K to accommodate Mesa in bug 1753340.
+  //
+  // Previously increased to 320K to avoid a stack overflow in the
+  // Intel Vulkan driver initialization in bug 1716120.
+  //
+  // Note: we only override it if it's limited already.
+  uint32_t stackSize = nsIThreadManager::DEFAULT_STACK_SIZE;
+  if (stackSize) {
+    stackSize =
+        std::max(stackSize, gfx::gfxVars::SupportsThreadsafeGL() &&
+                                    !gfx::gfxVars::UseCanvasRenderThread()
+                                ? 4096U << 10
+                                : 512U << 10);
+  }
+
+  nsCOMPtr<nsIThread> compositorThread;
+  nsresult rv = NS_NewNamedThread(
+      "Compositor", getter_AddRefs(compositorThread),
+      NS_NewRunnableFunction(
+          "CompositorThreadHolder::CompositorThreadHolderSetup",
+          []() {
+            sProfilerThreadId = profiler_current_thread_id();
+            sBackgroundHangMonitor = new mozilla::BackgroundHangMonitor(
+                "Compositor",
+                /* Timeout values are powers-of-two to enable us get better
+                   data. 128ms is chosen for transient hangs because 8Hz should
+                   be the minimally acceptable goal for Compositor
+                   responsiveness (normal goal is 60Hz). */
+                128,
+                /* 2048ms is chosen for permanent hangs because it's longer than
+                 * most Compositor hangs seen in the wild, but is short enough
+                 * to not miss getting native hang stacks. */
+                2048);
+            nsCOMPtr<nsIThread> thread = NS_GetCurrentThread();
+            static_cast<nsThread*>(thread.get())->SetUseHangMonitor(true);
+          }),
+      {.stackSize = stackSize});
+
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  CompositorBridgeParent::Setup();
+  ImageBridgeParent::Setup();
+
+  return compositorThread.forget();
+}
+
+void CompositorThreadHolder::Start() {
+  MOZ_ASSERT(NS_IsMainThread(), "Should be on the main Thread!");
+  MOZ_ASSERT(!sCompositorThreadHolder,
+             "The compositor thread has already been started!");
+
+  // We unset the holder instead of asserting because failing to start the
+  // compositor thread may not be a fatal error. As long as this succeeds in
+  // either the GPU process or the UI process, the user will have a usable
+  // browser. If we get neither, it will crash as soon as we try to post to the
+  // compositor thread for the first time.
+  sProfilerThreadId = ProfilerThreadId();
+  sCompositorThreadHolder = new CompositorThreadHolder();
+  if (!sCompositorThreadHolder->GetCompositorThread()) {
+    gfxCriticalNote << "Compositor thread not started ("
+                    << XRE_IsParentProcess() << ")";
+    sCompositorThreadHolder = nullptr;
+  }
+}
+
+void CompositorThreadHolder::Shutdown() {
+  MOZ_ASSERT(NS_IsMainThread(), "Should be on the main Thread!");
+  if (!sCompositorThreadHolder) {
+    // We've already shutdown or never started.
+    return;
+  }
+
+  ImageBridgeParent::Shutdown();
+  gfx::VRManagerParent::Shutdown();
+  MediaSystemResourceService::Shutdown();
+  CompositorManagerParent::Shutdown();
+  gfx::gfxGradientCache::Shutdown();
+
+  // Ensure there are no pending tasks that would cause an access to the
+  // thread's HangMonitor. APZ and Canvas can keep a reference to the compositor
+  // thread and may continue to dispatch tasks on it as the system shuts down.
+  CompositorThread()->Dispatch(NS_NewRunnableFunction(
+      "CompositorThreadHolder::Shutdown",
+      [compositorThreadHolder =
+           RefPtr<CompositorThreadHolder>(sCompositorThreadHolder),
+       backgroundHangMonitor = UniquePtr<mozilla::BackgroundHangMonitor>(
+           sBackgroundHangMonitor)]() {
+        VideoBridgeParent::UnregisterExternalImages();
+        nsCOMPtr<nsIThread> thread = NS_GetCurrentThread();
+        static_cast<nsThread*>(thread.get())->SetUseHangMonitor(false);
+      }));
+
+  sCompositorThreadHolder = nullptr;
+  sBackgroundHangMonitor = nullptr;
+
+  SpinEventLoopUntil("CompositorThreadHolder::Shutdown"_ns, [&]() {
+    bool finished = sFinishedCompositorShutDown;
+    return finished;
+  });
+
+  // At this point, the CompositorThreadHolder instance will have been
+  // destroyed, but the compositor thread itself may still be running due to
+  // APZ/Canvas code holding a reference to the underlying
+  // nsIThread/nsISerialEventTarget. Any tasks scheduled to run on the
+  // compositor thread earlier in this function will have been run to
+  // completion.
+  CompositorBridgeParent::FinishShutdown();
+}
+
+/* static */
+bool CompositorThreadHolder::IsInCompositorThread() {
+  if (!CompositorThread()) {
+    return false;
+  }
+  bool in = false;
+  MOZ_ALWAYS_SUCCEEDS(CompositorThread()->IsOnCurrentThread(&in));
+  return in;
+}
+
+/* static */
+ProfilerThreadId CompositorThreadHolder::GetThreadId() {
+  return sCompositorThreadHolder ? sProfilerThreadId : ProfilerThreadId();
+}
+
+}  // namespace layers
+}  // namespace mozilla
+
+bool NS_IsInCompositorThread() {
+  return mozilla::layers::CompositorThreadHolder::IsInCompositorThread();
+}
diff --git a/gfx/layers/ipc/CompositorThread.h b/gfx/layers/ipc/CompositorThread.h
new file mode 100644
index 0000000000..3352889982
--- /dev/null
+++ b/gfx/layers/ipc/CompositorThread.h
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef mozilla_layers_CompositorThread_h
+#define mozilla_layers_CompositorThread_h
+
+#include "nsISupportsImpl.h"
+#include "nsIThread.h"
+
+namespace mozilla::baseprofiler {
+class BaseProfilerThreadId;
+}
+using ProfilerThreadId = mozilla::baseprofiler::BaseProfilerThreadId;
+class nsIThread;
+
+namespace mozilla {
+namespace layers {
+
+class CompositorThreadHolder final {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING_WITH_DELETE_ON_MAIN_THREAD(
+      CompositorThreadHolder)
+
+ public:
+  CompositorThreadHolder();
+
+  nsIThread* GetCompositorThread() const { return mCompositorThread; }
+
+  /**
+   * Returns true if the calling thread is the compositor thread. This works
+   * even if the CompositorThread has begun to shutdown.
+   */
+  bool IsInThread() {
+    bool rv = false;
+    MOZ_ALWAYS_TRUE(NS_SUCCEEDED(mCompositorThread->IsOnCurrentThread(&rv)));
+    return rv;
+  }
+
+  nsresult Dispatch(already_AddRefed<nsIRunnable> event,
+                    uint32_t flags = nsIEventTarget::DISPATCH_NORMAL) {
+    return mCompositorThread->Dispatch(std::move(event), flags);
+  }
+
+  static CompositorThreadHolder* GetSingleton();
+
+  static bool IsActive() { return !!GetSingleton(); }
+
+  /**
+   * Creates the compositor thread and the global compositor map.
+   */
+  static void Start();
+
+  /*
+   * Waits for all [CrossProcess]CompositorBridgeParents to shutdown and
+   * releases compositor-thread owned resources.
+   */
+  static void Shutdown();
+
+  // Returns true if the calling thread is the compositor thread.
+  static bool IsInCompositorThread();
+
+  // Thread id to use as a MarkerThreadId option for profiler markers.
+  static ProfilerThreadId GetThreadId();
+
+ private:
+  ~CompositorThreadHolder();
+
+  const nsCOMPtr<nsIThread> mCompositorThread;
+
+  static already_AddRefed<nsIThread> CreateCompositorThread();
+
+  friend class CompositorBridgeParent;
+};
+
+nsIThread* CompositorThread();
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CompositorThread_h
diff --git a/gfx/layers/ipc/CompositorVsyncScheduler.cpp b/gfx/layers/ipc/CompositorVsyncScheduler.cpp
new file mode 100644
index 0000000000..6ef8903015
--- /dev/null
+++ b/gfx/layers/ipc/CompositorVsyncScheduler.cpp
@@ -0,0 +1,382 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/CompositorVsyncScheduler.h"
+
+#include <stdio.h>        // for fprintf, stdout
+#include <stdint.h>       // for uint64_t
+#include "base/task.h"    // for CancelableTask, etc
+#include "base/thread.h"  // for Thread
+#include "gfxPlatform.h"  // for gfxPlatform
+#ifdef MOZ_WIDGET_GTK
+#  include "gfxPlatformGtk.h"  // for gfxPlatform
+#endif
+#include "mozilla/AutoRestore.h"  // for AutoRestore
+#include "mozilla/DebugOnly.h"    // for DebugOnly
+#include "mozilla/StaticPrefs_gfx.h"
+#include "mozilla/StaticPrefs_layers.h"
+#include "mozilla/gfx/2D.h"     // for DrawTarget
+#include "mozilla/gfx/Point.h"  // for IntSize
+#include "mozilla/gfx/Rect.h"   // for IntSize
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/CompositorVsyncSchedulerOwner.h"
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "nsCOMPtr.h"          // for already_AddRefed
+#include "nsDebug.h"           // for NS_ASSERTION, etc
+#include "nsISupportsImpl.h"   // for MOZ_COUNT_CTOR, etc
+#include "nsIWidget.h"         // for nsIWidget
+#include "nsThreadUtils.h"     // for NS_IsMainThread
+#include "mozilla/Telemetry.h"
+#include "mozilla/VsyncDispatcher.h"
+#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
+#  include "VsyncSource.h"
+#endif
+#include "mozilla/widget/CompositorWidget.h"
+#include "VRManager.h"
+
+namespace mozilla {
+
+namespace layers {
+
+using namespace mozilla::gfx;
+
+CompositorVsyncScheduler::Observer::Observer(CompositorVsyncScheduler* aOwner)
+    : mMutex("CompositorVsyncScheduler.Observer.Mutex"), mOwner(aOwner) {}
+
+CompositorVsyncScheduler::Observer::~Observer() { MOZ_ASSERT(!mOwner); }
+
+void CompositorVsyncScheduler::Observer::NotifyVsync(const VsyncEvent& aVsync) {
+  MutexAutoLock lock(mMutex);
+  if (!mOwner) {
+    return;
+  }
+  mOwner->NotifyVsync(aVsync);
+}
+
+void CompositorVsyncScheduler::Observer::Destroy() {
+  MutexAutoLock lock(mMutex);
+  mOwner = nullptr;
+}
+
+CompositorVsyncScheduler::CompositorVsyncScheduler(
+    CompositorVsyncSchedulerOwner* aVsyncSchedulerOwner,
+    widget::CompositorWidget* aWidget)
+    : mVsyncSchedulerOwner(aVsyncSchedulerOwner),
+      mLastComposeTime(SampleTime::FromNow()),
+      mLastVsyncTime(TimeStamp::Now()),
+      mLastVsyncOutputTime(TimeStamp::Now()),
+      mIsObservingVsync(false),
+      mRendersDelayedByVsyncReasons(wr::RenderReasons::NONE),
+      mVsyncNotificationsSkipped(0),
+      mWidget(aWidget),
+      mCurrentCompositeTaskMonitor("CurrentCompositeTaskMonitor"),
+      mCurrentCompositeTask(nullptr),
+      mCurrentCompositeTaskReasons(wr::RenderReasons::NONE),
+      mCurrentVRTaskMonitor("CurrentVRTaskMonitor"),
+      mCurrentVRTask(nullptr) {
+  mVsyncObserver = new Observer(this);
+
+  // mAsapScheduling is set on the main thread during init,
+  // but is only accessed after on the compositor thread.
+  mAsapScheduling =
+      StaticPrefs::layers_offmainthreadcomposition_frame_rate() == 0 ||
+      gfxPlatform::IsInLayoutAsapMode();
+}
+
+CompositorVsyncScheduler::~CompositorVsyncScheduler() {
+  MOZ_ASSERT(!mIsObservingVsync);
+  MOZ_ASSERT(!mVsyncObserver);
+  // The CompositorVsyncDispatcher is cleaned up before this in the
+  // nsBaseWidget, which stops vsync listeners
+  mVsyncSchedulerOwner = nullptr;
+}
+
+void CompositorVsyncScheduler::Destroy() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  if (!mVsyncObserver) {
+    // Destroy was already called on this object.
+    return;
+  }
+  UnobserveVsync();
+  mVsyncObserver->Destroy();
+  mVsyncObserver = nullptr;
+
+  mCompositeRequestedAt = TimeStamp();
+  CancelCurrentCompositeTask();
+  CancelCurrentVRTask();
+}
+
+void CompositorVsyncScheduler::PostCompositeTask(const VsyncEvent& aVsyncEvent,
+                                                 wr::RenderReasons aReasons) {
+  MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+  mCurrentCompositeTaskReasons = mCurrentCompositeTaskReasons | aReasons;
+  if (mCurrentCompositeTask == nullptr && CompositorThread()) {
+    RefPtr<CancelableRunnable> task =
+        NewCancelableRunnableMethod<VsyncEvent, wr::RenderReasons>(
+            "layers::CompositorVsyncScheduler::Composite", this,
+            &CompositorVsyncScheduler::Composite, aVsyncEvent, aReasons);
+    mCurrentCompositeTask = task;
+    CompositorThread()->Dispatch(task.forget());
+  }
+}
+
+void CompositorVsyncScheduler::PostVRTask(TimeStamp aTimestamp) {
+  MonitorAutoLock lockVR(mCurrentVRTaskMonitor);
+  if (mCurrentVRTask == nullptr && CompositorThread()) {
+    RefPtr<CancelableRunnable> task = NewCancelableRunnableMethod<TimeStamp>(
+        "layers::CompositorVsyncScheduler::DispatchVREvents", this,
+        &CompositorVsyncScheduler::DispatchVREvents, aTimestamp);
+    mCurrentVRTask = task;
+    CompositorThread()->Dispatch(task.forget());
+  }
+}
+
+void CompositorVsyncScheduler::ScheduleComposition(wr::RenderReasons aReasons) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (!mVsyncObserver) {
+    // Destroy was already called on this object.
+    return;
+  }
+
+  // Make a synthetic vsync event for the calls to PostCompositeTask below.
+  TimeStamp vsyncTime = TimeStamp::Now();
+  TimeStamp outputTime = vsyncTime + mVsyncSchedulerOwner->GetVsyncInterval();
+  VsyncEvent vsyncEvent(VsyncId(), vsyncTime, outputTime);
+
+  if (mAsapScheduling) {
+    // Used only for performance testing purposes, and when recording/replaying
+    // to ensure that graphics are up to date.
+    PostCompositeTask(vsyncEvent, aReasons);
+  } else {
+    if (!mCompositeRequestedAt) {
+      mCompositeRequestedAt = TimeStamp::Now();
+    }
+    if (!mIsObservingVsync && mCompositeRequestedAt) {
+      ObserveVsync();
+      // Starting to observe vsync is an async operation that goes
+      // through the main thread of the UI process. It's possible that
+      // we're blocking there waiting on a composite, so schedule an initial
+      // one now to get things started.
+      PostCompositeTask(vsyncEvent,
+                        aReasons | wr::RenderReasons::START_OBSERVING_VSYNC);
+    } else {
+      mRendersDelayedByVsyncReasons = aReasons;
+    }
+  }
+}
+
+void CompositorVsyncScheduler::NotifyVsync(const VsyncEvent& aVsync) {
+  // Called from the vsync dispatch thread. When in the GPU Process, that's
+  // the same as the compositor thread.
+#ifdef DEBUG
+#  ifdef MOZ_WAYLAND
+  // On Wayland, we dispatch vsync from the main thread, without a GPU process.
+  // To allow this, we skip the following asserts if we're currently utilizing
+  // the Wayland backend. The IsParentProcess guard is needed to ensure that
+  // we don't accidentally attempt to initialize the gfxPlatform in the GPU
+  // process on X11.
+  if (!XRE_IsParentProcess() ||
+      !gfxPlatformGtk::GetPlatform()->IsWaylandDisplay())
+#  endif  // MOZ_WAYLAND
+  {
+    MOZ_ASSERT_IF(XRE_IsParentProcess(),
+                  !CompositorThreadHolder::IsInCompositorThread());
+    MOZ_ASSERT(!NS_IsMainThread());
+  }
+
+  MOZ_ASSERT_IF(XRE_GetProcessType() == GeckoProcessType_GPU,
+                CompositorThreadHolder::IsInCompositorThread());
+#endif  // DEBUG
+
+#if defined(MOZ_WIDGET_ANDROID)
+  gfx::VRManager* vm = gfx::VRManager::Get();
+  if (!vm->IsPresenting()) {
+    PostCompositeTask(aVsync, wr::RenderReasons::VSYNC);
+  }
+#else
+  PostCompositeTask(aVsync, wr::RenderReasons::VSYNC);
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  PostVRTask(aVsync.mTime);
+}
+
+void CompositorVsyncScheduler::CancelCurrentVRTask() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread() ||
+             NS_IsMainThread());
+  MonitorAutoLock lock(mCurrentVRTaskMonitor);
+  if (mCurrentVRTask) {
+    mCurrentVRTask->Cancel();
+    mCurrentVRTask = nullptr;
+  }
+}
+
+wr::RenderReasons CompositorVsyncScheduler::CancelCurrentCompositeTask() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread() ||
+             NS_IsMainThread());
+  MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+  wr::RenderReasons canceledTaskRenderReasons = mCurrentCompositeTaskReasons;
+  mCurrentCompositeTaskReasons = wr::RenderReasons::NONE;
+  if (mCurrentCompositeTask) {
+    mCurrentCompositeTask->Cancel();
+    mCurrentCompositeTask = nullptr;
+  }
+
+  return canceledTaskRenderReasons;
+}
+
+void CompositorVsyncScheduler::Composite(const VsyncEvent& aVsyncEvent,
+                                         wr::RenderReasons aReasons) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MOZ_ASSERT(mVsyncSchedulerOwner);
+
+  {  // scope lock
+    MonitorAutoLock lock(mCurrentCompositeTaskMonitor);
+    aReasons =
+        aReasons | mCurrentCompositeTaskReasons | mRendersDelayedByVsyncReasons;
+    mCurrentCompositeTaskReasons = wr::RenderReasons::NONE;
+    mRendersDelayedByVsyncReasons = wr::RenderReasons::NONE;
+    mCurrentCompositeTask = nullptr;
+  }
+
+  mLastVsyncTime = aVsyncEvent.mTime;
+  mLastVsyncOutputTime = aVsyncEvent.mOutputTime;
+  mLastVsyncId = aVsyncEvent.mId;
+
+  if (!mAsapScheduling) {
+    // Some early exit conditions if we're not in ASAP mode
+    if (aVsyncEvent.mTime < mLastComposeTime.Time()) {
+      // We can sometimes get vsync timestamps that are in the past
+      // compared to the last compose with force composites.
+      // In those cases, wait until the next vsync;
+      return;
+    }
+
+    if (mVsyncSchedulerOwner->IsPendingComposite()) {
+      // If previous composite is still on going, finish it and wait for the
+      // next vsync.
+      mVsyncSchedulerOwner->FinishPendingComposite();
+      return;
+    }
+  }
+
+  if (mCompositeRequestedAt || mAsapScheduling) {
+    mCompositeRequestedAt = TimeStamp();
+    mLastComposeTime = SampleTime::FromVsync(aVsyncEvent.mTime);
+
+    // Tell the owner to do a composite
+    mVsyncSchedulerOwner->CompositeToTarget(aVsyncEvent.mId, aReasons, nullptr,
+                                            nullptr);
+
+    mVsyncNotificationsSkipped = 0;
+
+    TimeDuration compositeFrameTotal = TimeStamp::Now() - aVsyncEvent.mTime;
+    mozilla::Telemetry::Accumulate(
+        mozilla::Telemetry::COMPOSITE_FRAME_ROUNDTRIP_TIME,
+        compositeFrameTotal.ToMilliseconds());
+  } else if (mVsyncNotificationsSkipped++ >
+             StaticPrefs::gfx_vsync_compositor_unobserve_count_AtStartup()) {
+    UnobserveVsync();
+  }
+}
+
+void CompositorVsyncScheduler::ForceComposeToTarget(wr::RenderReasons aReasons,
+                                                    gfx::DrawTarget* aTarget,
+                                                    const IntRect* aRect) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+
+  /**
+   * bug 1138502 - There are cases such as during long-running window resizing
+   * events where we receive many force-composites. We also continue to get
+   * vsync notifications. Because the force-composites trigger compositing and
+   * clear the mCompositeRequestedAt timestamp, the vsync notifications will not
+   * need to do anything and so will increment the mVsyncNotificationsSkipped
+   * counter to indicate the vsync was ignored. If this happens enough times, we
+   * will disable listening for vsync entirely. On the next force-composite we
+   * will enable listening for vsync again, and continued force-composites and
+   * vsyncs will cause oscillation between observing vsync and not. On some
+   * platforms, enabling/disabling vsync is not free and this oscillating
+   * behavior causes a performance hit. In order to avoid this problem, we reset
+   * the mVsyncNotificationsSkipped counter to keep vsync enabled.
+   */
+  mVsyncNotificationsSkipped = 0;
+
+  mLastComposeTime = SampleTime::FromNow();
+  MOZ_ASSERT(mVsyncSchedulerOwner);
+  mVsyncSchedulerOwner->CompositeToTarget(VsyncId(), aReasons, aTarget, aRect);
+}
+
+bool CompositorVsyncScheduler::NeedsComposite() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return (bool)mCompositeRequestedAt;
+}
+
+bool CompositorVsyncScheduler::FlushPendingComposite() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (mCompositeRequestedAt) {
+    wr::RenderReasons reasons = CancelCurrentCompositeTask();
+    ForceComposeToTarget(reasons, nullptr, nullptr);
+    return true;
+  }
+  return false;
+}
+
+void CompositorVsyncScheduler::ObserveVsync() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mWidget->ObserveVsync(mVsyncObserver);
+  mIsObservingVsync = true;
+}
+
+void CompositorVsyncScheduler::UnobserveVsync() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mWidget->ObserveVsync(nullptr);
+  mIsObservingVsync = false;
+}
+
+void CompositorVsyncScheduler::DispatchVREvents(TimeStamp aVsyncTimestamp) {
+  {
+    MonitorAutoLock lock(mCurrentVRTaskMonitor);
+    mCurrentVRTask = nullptr;
+  }
+  // This only allows to be called by CompositorVsyncScheduler::PostVRTask()
+  // When the process is going to shutdown, the runnable has chance to be
+  // executed by other threads, we only want it to be run in the compositor
+  // thread.
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    return;
+  }
+
+  VRManager* vm = VRManager::Get();
+  vm->NotifyVsync(aVsyncTimestamp);
+}
+
+const SampleTime& CompositorVsyncScheduler::GetLastComposeTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastComposeTime;
+}
+
+const TimeStamp& CompositorVsyncScheduler::GetLastVsyncTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncTime;
+}
+
+const TimeStamp& CompositorVsyncScheduler::GetLastVsyncOutputTime() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncOutputTime;
+}
+
+const VsyncId& CompositorVsyncScheduler::GetLastVsyncId() const {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  return mLastVsyncId;
+}
+
+void CompositorVsyncScheduler::UpdateLastComposeTime() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  mLastComposeTime = SampleTime::FromNow();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/CompositorVsyncScheduler.h b/gfx/layers/ipc/CompositorVsyncScheduler.h
new file mode 100644
index 0000000000..da0d3d453a
--- /dev/null
+++ b/gfx/layers/ipc/CompositorVsyncScheduler.h
@@ -0,0 +1,187 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorVsyncScheduler_h
+#define mozilla_layers_CompositorVsyncScheduler_h
+
+#include <stdint.h>  // for uint64_t
+
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/Monitor.h"     // for Monitor
+#include "mozilla/RefPtr.h"      // for RefPtr
+#include "mozilla/TimeStamp.h"   // for TimeStamp
+#include "mozilla/gfx/Point.h"   // for IntSize
+#include "mozilla/layers/SampleTime.h"
+#include "mozilla/webrender/webrender_ffi.h"
+#include "mozilla/VsyncDispatcher.h"
+#include "mozilla/widget/CompositorWidget.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+class CancelableRunnable;
+class Runnable;
+
+namespace gfx {
+class DrawTarget;
+}  // namespace gfx
+
+namespace layers {
+
+class CompositorVsyncSchedulerOwner;
+
+/**
+ * Manages the vsync (de)registration and tracking on behalf of the
+ * compositor when it need to paint.
+ * Turns vsync notifications into scheduled composites.
+ **/
+class CompositorVsyncScheduler {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncScheduler)
+
+ public:
+  CompositorVsyncScheduler(CompositorVsyncSchedulerOwner* aVsyncSchedulerOwner,
+                           widget::CompositorWidget* aWidget);
+
+  /**
+   * Notify this class of a vsync. This will trigger a composite if one is
+   * needed. This must be called from the vsync dispatch thread.
+   */
+  void NotifyVsync(const VsyncEvent& aVsync);
+
+  /**
+   * Do cleanup. This must be called on the compositor thread.
+   */
+  void Destroy();
+
+  /**
+   * Notify this class that a composition is needed. This will trigger a
+   * composition soon (likely at the next vsync). This must be called on the
+   * compositor thread.
+   */
+  void ScheduleComposition(wr::RenderReasons aReasons);
+
+  /**
+   * Cancel any composite task that has been scheduled but hasn't run yet.
+   *
+   * Returns the render reasons of the canceled task if any.
+   */
+  wr::RenderReasons CancelCurrentCompositeTask();
+
+  /**
+   * Check if a composite is pending. This is generally true between a call
+   * to ScheduleComposition() and the time the composite happens.
+   */
+  bool NeedsComposite();
+
+  /**
+   * Force a composite to happen right away, without waiting for the next vsync.
+   * This must be called on the compositor thread.
+   */
+  void ForceComposeToTarget(wr::RenderReasons aReasons,
+                            gfx::DrawTarget* aTarget,
+                            const gfx::IntRect* aRect);
+
+  /**
+   * If a composite is pending, force it to trigger right away. This must be
+   * called on the compositor thread. Returns true if there was a composite
+   * flushed.
+   */
+  bool FlushPendingComposite();
+
+  /**
+   * Return the vsync timestamp of the last or ongoing composite. Must be called
+   * on the compositor thread.
+   */
+  const SampleTime& GetLastComposeTime() const;
+
+  /**
+   * Return the vsync timestamp and id of the most recently received
+   * vsync event. Must be called on the compositor thread.
+   */
+  const TimeStamp& GetLastVsyncTime() const;
+  const TimeStamp& GetLastVsyncOutputTime() const;
+  const VsyncId& GetLastVsyncId() const;
+
+  /**
+   * Update LastCompose TimeStamp to current timestamp.
+   * The function is typically used when composition is handled outside the
+   * CompositorVsyncScheduler.
+   */
+  void UpdateLastComposeTime();
+
+ private:
+  virtual ~CompositorVsyncScheduler();
+
+  // Post a task to run Composite() on the compositor thread, if there isn't
+  // such a task already queued. Can be called from any thread.
+  void PostCompositeTask(const VsyncEvent& aVsyncEvent,
+                         wr::RenderReasons aReasons);
+
+  // Post a task to run DispatchVREvents() on the VR thread, if there isn't
+  // such a task already queued. Can be called from any thread.
+  void PostVRTask(TimeStamp aTimestamp);
+
+  /**
+   * Cancel any VR task that has been scheduled but hasn't run yet.
+   */
+  void CancelCurrentVRTask();
+
+  // This gets run at vsync time and "does" a composite (which really means
+  // update internal state and call the owner to do the composite).
+  void Composite(const VsyncEvent& aVsyncEvent, wr::RenderReasons aReasons);
+
+  void ObserveVsync();
+  void UnobserveVsync();
+
+  void DispatchVREvents(TimeStamp aVsyncTimestamp);
+
+  class Observer final : public VsyncObserver {
+    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(CompositorVsyncScheduler::Observer,
+                                          override)
+
+   public:
+    explicit Observer(CompositorVsyncScheduler* aOwner);
+    void NotifyVsync(const VsyncEvent& aVsync) override;
+    void Destroy();
+
+   private:
+    virtual ~Observer();
+
+    Mutex mMutex;
+    // Hold raw pointer to avoid mutual reference.
+    CompositorVsyncScheduler* mOwner;
+  };
+
+  CompositorVsyncSchedulerOwner* mVsyncSchedulerOwner;
+  SampleTime mLastComposeTime;
+  TimeStamp mLastVsyncTime;
+  TimeStamp mLastVsyncOutputTime;
+  VsyncId mLastVsyncId;
+
+  bool mAsapScheduling;
+  bool mIsObservingVsync;
+  // Accessed on the compositor thread.
+  wr::RenderReasons mRendersDelayedByVsyncReasons;
+  TimeStamp mCompositeRequestedAt;
+  int32_t mVsyncNotificationsSkipped;
+  widget::CompositorWidget* mWidget;
+  RefPtr<CompositorVsyncScheduler::Observer> mVsyncObserver;
+
+  mozilla::Monitor mCurrentCompositeTaskMonitor;
+  RefPtr<CancelableRunnable> mCurrentCompositeTask
+      MOZ_GUARDED_BY(mCurrentCompositeTaskMonitor);
+  // Accessed on multiple threads, guarded by mCurrentCompositeTaskMonitor.
+  wr::RenderReasons mCurrentCompositeTaskReasons
+      MOZ_GUARDED_BY(mCurrentCompositeTaskMonitor);
+
+  mozilla::Monitor mCurrentVRTaskMonitor;
+  RefPtr<CancelableRunnable> mCurrentVRTask
+      MOZ_GUARDED_BY(mCurrentVRTaskMonitor);
+};
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CompositorVsyncScheduler_h
diff --git a/gfx/layers/ipc/CompositorVsyncSchedulerOwner.h b/gfx/layers/ipc/CompositorVsyncSchedulerOwner.h
new file mode 100644
index 0000000000..ac147fd241
--- /dev/null
+++ b/gfx/layers/ipc/CompositorVsyncSchedulerOwner.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorVsyncSchedulerOwner_h
+#define mozilla_layers_CompositorVsyncSchedulerOwner_h
+
+#include "mozilla/VsyncDispatcher.h"
+#include "mozilla/webrender/webrender_ffi.h"
+
+namespace mozilla {
+
+namespace gfx {
+class DrawTarget;
+}  // namespace gfx
+
+namespace layers {
+
+class CompositorVsyncSchedulerOwner {
+ public:
+  virtual bool IsPendingComposite() = 0;
+  virtual void FinishPendingComposite() = 0;
+  virtual void CompositeToTarget(VsyncId aId, wr::RenderReasons aReasons,
+                                 gfx::DrawTarget* aTarget,
+                                 const gfx::IntRect* aRect = nullptr) = 0;
+  virtual TimeDuration GetVsyncInterval() const = 0;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_CompositorVsyncSchedulerOwner_h
diff --git a/gfx/layers/ipc/ContentCompositorBridgeParent.cpp b/gfx/layers/ipc/ContentCompositorBridgeParent.cpp
new file mode 100644
index 0000000000..4936cbbbb8
--- /dev/null
+++ b/gfx/layers/ipc/ContentCompositorBridgeParent.cpp
@@ -0,0 +1,438 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/ContentCompositorBridgeParent.h"
+
+#include <stdint.h>  // for uint64_t
+
+#include "apz/src/APZCTreeManager.h"  // for APZCTreeManager
+#include "gfxUtils.h"
+#ifdef XP_WIN
+#  include "mozilla/gfx/DeviceManagerDx.h"  // for DeviceManagerDx
+#  include "mozilla/layers/ImageDataSerializer.h"
+#endif
+#include "mozilla/layers/AnimationHelper.h"  // for CompositorAnimationStorage
+#include "mozilla/layers/APZCTreeManagerParent.h"  // for APZCTreeManagerParent
+#include "mozilla/layers/APZUpdater.h"             // for APZUpdater
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/layers/CompositorOptions.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/LayerTreeOwnerTracker.h"
+#include "mozilla/layers/RemoteContentController.h"
+#include "mozilla/layers/WebRenderBridgeParent.h"
+#include "mozilla/layers/AsyncImagePipelineManager.h"
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "nsDebug.h"           // for NS_ASSERTION, etc
+#include "nsTArray.h"          // for nsTArray
+#include "nsXULAppAPI.h"       // for XRE_GetIOMessageLoop
+#include "mozilla/Unused.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/BaseProfilerMarkerTypes.h"
+#include "GeckoProfiler.h"
+
+namespace mozilla::layers {
+
+void EraseLayerState(LayersId aId);
+
+void ContentCompositorBridgeParent::ActorDestroy(ActorDestroyReason aWhy) {
+  mCanSend = false;
+
+  // We must keep this object alive untill the code handling message
+  // reception is finished on this thread.
+  GetCurrentSerialEventTarget()->Dispatch(NewRunnableMethod(
+      "layers::ContentCompositorBridgeParent::DeferredDestroy", this,
+      &ContentCompositorBridgeParent::DeferredDestroy));
+}
+
+PAPZCTreeManagerParent*
+ContentCompositorBridgeParent::AllocPAPZCTreeManagerParent(
+    const LayersId& aLayersId) {
+  // Check to see if this child process has access to this layer tree.
+  if (!LayerTreeOwnerTracker::Get()->IsMapped(aLayersId, OtherPid())) {
+    NS_ERROR(
+        "Unexpected layers id in AllocPAPZCTreeManagerParent; dropping "
+        "message...");
+    return nullptr;
+  }
+
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState& state =
+      CompositorBridgeParent::sIndirectLayerTrees[aLayersId];
+
+  // If the widget has shutdown its compositor, we may not have had a chance yet
+  // to unmap our layers id, and we could get here without a parent compositor.
+  // In this case return an empty APZCTM.
+  if (!state.mParent) {
+    // Note: we immediately call ClearTree since otherwise the APZCTM will
+    // retain a reference to itself, through the checkerboard observer.
+    LayersId dummyId{0};
+    const bool connectedToWebRender = false;
+    RefPtr<APZCTreeManager> temp = APZCTreeManager::Create(dummyId);
+    RefPtr<APZUpdater> tempUpdater = new APZUpdater(temp, connectedToWebRender);
+    tempUpdater->ClearTree(dummyId);
+    return new APZCTreeManagerParent(aLayersId, temp, tempUpdater);
+  }
+
+  // If we do not have APZ enabled, we should gracefully fail.
+  if (!state.mParent->GetOptions().UseAPZ()) {
+    return nullptr;
+  }
+
+  state.mParent->AllocateAPZCTreeManagerParent(lock, aLayersId, state);
+  return state.mApzcTreeManagerParent;
+}
+
+bool ContentCompositorBridgeParent::DeallocPAPZCTreeManagerParent(
+    PAPZCTreeManagerParent* aActor) {
+  APZCTreeManagerParent* parent = static_cast<APZCTreeManagerParent*>(aActor);
+
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  auto iter =
+      CompositorBridgeParent::sIndirectLayerTrees.find(parent->GetLayersId());
+  if (iter != CompositorBridgeParent::sIndirectLayerTrees.end()) {
+    CompositorBridgeParent::LayerTreeState& state = iter->second;
+    MOZ_ASSERT(state.mApzcTreeManagerParent == parent);
+    state.mApzcTreeManagerParent = nullptr;
+  }
+
+  delete parent;
+
+  return true;
+}
+
+PAPZParent* ContentCompositorBridgeParent::AllocPAPZParent(
+    const LayersId& aLayersId) {
+  // Check to see if this child process has access to this layer tree.
+  if (!LayerTreeOwnerTracker::Get()->IsMapped(aLayersId, OtherPid())) {
+    NS_ERROR("Unexpected layers id in AllocPAPZParent; dropping message...");
+    return nullptr;
+  }
+
+  RemoteContentController* controller = new RemoteContentController();
+
+  // Increment the controller's refcount before we return it. This will keep the
+  // controller alive until it is released by IPDL in DeallocPAPZParent.
+  controller->AddRef();
+
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  CompositorBridgeParent::LayerTreeState& state =
+      CompositorBridgeParent::sIndirectLayerTrees[aLayersId];
+  MOZ_ASSERT(!state.mController);
+  state.mController = controller;
+
+  return controller;
+}
+
+bool ContentCompositorBridgeParent::DeallocPAPZParent(PAPZParent* aActor) {
+  RemoteContentController* controller =
+      static_cast<RemoteContentController*>(aActor);
+  controller->Release();
+  return true;
+}
+
+PWebRenderBridgeParent*
+ContentCompositorBridgeParent::AllocPWebRenderBridgeParent(
+    const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize& aSize,
+    const WindowKind& aWindowKind) {
+  LayersId layersId = wr::AsLayersId(aPipelineId);
+  // Check to see if this child process has access to this layer tree.
+  if (!LayerTreeOwnerTracker::Get()->IsMapped(layersId, OtherPid())) {
+    NS_ERROR(
+        "Unexpected layers id in AllocPWebRenderBridgeParent; dropping "
+        "message...");
+    return nullptr;
+  }
+
+  RefPtr<CompositorBridgeParent> cbp = nullptr;
+  RefPtr<WebRenderBridgeParent> root = nullptr;
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+    MOZ_ASSERT(CompositorBridgeParent::sIndirectLayerTrees.find(layersId) !=
+               CompositorBridgeParent::sIndirectLayerTrees.end());
+    MOZ_ASSERT(
+        CompositorBridgeParent::sIndirectLayerTrees[layersId].mWrBridge ==
+        nullptr);
+    cbp = CompositorBridgeParent::sIndirectLayerTrees[layersId].mParent;
+    if (cbp) {
+      root = CompositorBridgeParent::sIndirectLayerTrees[cbp->RootLayerTreeId()]
+                 .mWrBridge;
+    }
+  }
+
+  RefPtr<wr::WebRenderAPI> api;
+  if (root) {
+    api = root->GetWebRenderAPI();
+  }
+
+  if (!root || !api) {
+    // This could happen when this function is called after
+    // CompositorBridgeParent destruction. This was observed during Tab move
+    // between different windows.
+    NS_WARNING(
+        nsPrintfCString("Created child without a matching parent? root %p",
+                        root.get())
+            .get());
+    nsCString error("NO_PARENT");
+    WebRenderBridgeParent* parent =
+        WebRenderBridgeParent::CreateDestroyed(aPipelineId, std::move(error));
+    parent->AddRef();  // IPDL reference
+    return parent;
+  }
+
+  api = api->Clone();
+  RefPtr<AsyncImagePipelineManager> holder = root->AsyncImageManager();
+  WebRenderBridgeParent* parent = new WebRenderBridgeParent(
+      this, aPipelineId, nullptr, root->CompositorScheduler(), std::move(api),
+      std::move(holder), cbp->GetVsyncInterval());
+  parent->AddRef();  // IPDL reference
+
+  {  // scope lock
+    StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+    CompositorBridgeParent::sIndirectLayerTrees[layersId]
+        .mContentCompositorBridgeParent = this;
+    CompositorBridgeParent::sIndirectLayerTrees[layersId].mWrBridge = parent;
+  }
+
+  return parent;
+}
+
+bool ContentCompositorBridgeParent::DeallocPWebRenderBridgeParent(
+    PWebRenderBridgeParent* aActor) {
+  WebRenderBridgeParent* parent = static_cast<WebRenderBridgeParent*>(aActor);
+  EraseLayerState(wr::AsLayersId(parent->PipelineId()));
+  parent->Release();  // IPDL reference
+  return true;
+}
+
+mozilla::ipc::IPCResult ContentCompositorBridgeParent::RecvNotifyChildCreated(
+    const LayersId& child, CompositorOptions* aOptions) {
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  for (auto it = CompositorBridgeParent::sIndirectLayerTrees.begin();
+       it != CompositorBridgeParent::sIndirectLayerTrees.end(); it++) {
+    CompositorBridgeParent::LayerTreeState& lts = it->second;
+    if (lts.mParent && lts.mContentCompositorBridgeParent == this) {
+      lts.mParent->NotifyChildCreated(child);
+      *aOptions = lts.mParent->GetOptions();
+      return IPC_OK();
+    }
+  }
+  return IPC_FAIL_NO_REASON(this);
+}
+
+mozilla::ipc::IPCResult
+ContentCompositorBridgeParent::RecvMapAndNotifyChildCreated(
+    const LayersId& child, const base::ProcessId& pid,
+    CompositorOptions* aOptions) {
+  // This can only be called from the browser process, as the mapping
+  // ensures proper window ownership of layer trees.
+  return IPC_FAIL_NO_REASON(this);
+}
+
+mozilla::ipc::IPCResult
+ContentCompositorBridgeParent::RecvNotifyMemoryPressure() {
+  // This can only be called from the browser process.
+  return IPC_FAIL_NO_REASON(this);
+}
+
+mozilla::ipc::IPCResult ContentCompositorBridgeParent::RecvCheckContentOnlyTDR(
+    const uint32_t& sequenceNum, bool* isContentOnlyTDR) {
+  *isContentOnlyTDR = false;
+#ifdef XP_WIN
+  gfx::ContentDeviceData compositor;
+
+  gfx::DeviceManagerDx* dm = gfx::DeviceManagerDx::Get();
+
+  // Check that the D3D11 device sequence numbers match.
+  gfx::D3D11DeviceStatus status;
+  dm->ExportDeviceInfo(&status);
+
+  if (sequenceNum == static_cast<uint32_t>(status.sequenceNumber()) &&
+      !dm->HasDeviceReset()) {
+    *isContentOnlyTDR = true;
+  }
+
+#endif
+  return IPC_OK();
+};
+
+void ContentCompositorBridgeParent::DidCompositeLocked(
+    LayersId aId, const VsyncId& aVsyncId, TimeStamp& aCompositeStart,
+    TimeStamp& aCompositeEnd) {
+  CompositorBridgeParent::sIndirectLayerTreesLock.AssertCurrentThreadOwns();
+  if (CompositorBridgeParent::sIndirectLayerTrees[aId].mWrBridge) {
+    MOZ_ASSERT(false);  // this should never get called for a WR compositor
+  }
+}
+
+bool ContentCompositorBridgeParent::SetTestSampleTime(const LayersId& aId,
+                                                      const TimeStamp& aTime) {
+  MOZ_ASSERT(aId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aId);
+  if (!state) {
+    return false;
+  }
+
+  MOZ_ASSERT(state->mParent);
+  return state->mParent->SetTestSampleTime(aId, aTime);
+}
+
+void ContentCompositorBridgeParent::LeaveTestMode(const LayersId& aId) {
+  MOZ_ASSERT(aId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aId);
+  if (!state) {
+    return;
+  }
+
+  MOZ_ASSERT(state->mParent);
+  state->mParent->LeaveTestMode(aId);
+}
+
+void ContentCompositorBridgeParent::SetTestAsyncScrollOffset(
+    const LayersId& aLayersId, const ScrollableLayerGuid::ViewID& aScrollId,
+    const CSSPoint& aPoint) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state) {
+    return;
+  }
+
+  MOZ_ASSERT(state->mParent);
+  state->mParent->SetTestAsyncScrollOffset(aLayersId, aScrollId, aPoint);
+}
+
+void ContentCompositorBridgeParent::SetTestAsyncZoom(
+    const LayersId& aLayersId, const ScrollableLayerGuid::ViewID& aScrollId,
+    const LayerToParentLayerScale& aZoom) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state) {
+    return;
+  }
+
+  MOZ_ASSERT(state->mParent);
+  state->mParent->SetTestAsyncZoom(aLayersId, aScrollId, aZoom);
+}
+
+void ContentCompositorBridgeParent::FlushApzRepaints(
+    const LayersId& aLayersId) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state || !state->mParent) {
+    return;
+  }
+
+  state->mParent->FlushApzRepaints(aLayersId);
+}
+
+void ContentCompositorBridgeParent::GetAPZTestData(const LayersId& aLayersId,
+                                                   APZTestData* aOutData) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state || !state->mParent) {
+    return;
+  }
+
+  state->mParent->GetAPZTestData(aLayersId, aOutData);
+}
+
+void ContentCompositorBridgeParent::GetFrameUniformity(
+    const LayersId& aLayersId, FrameUniformityData* aOutData) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state || !state->mParent) {
+    return;
+  }
+
+  state->mParent->GetFrameUniformity(aLayersId, aOutData);
+}
+
+void ContentCompositorBridgeParent::SetConfirmedTargetAPZC(
+    const LayersId& aLayersId, const uint64_t& aInputBlockId,
+    nsTArray<ScrollableLayerGuid>&& aTargets) {
+  MOZ_ASSERT(aLayersId.IsValid());
+  const CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state || !state->mParent) {
+    return;
+  }
+
+  state->mParent->SetConfirmedTargetAPZC(aLayersId, aInputBlockId,
+                                         std::move(aTargets));
+}
+
+void ContentCompositorBridgeParent::DeferredDestroy() { mSelfRef = nullptr; }
+
+ContentCompositorBridgeParent::~ContentCompositorBridgeParent() {
+  MOZ_ASSERT(XRE_GetIOMessageLoop());
+}
+
+PTextureParent* ContentCompositorBridgeParent::AllocPTextureParent(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+    const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+    const LayersId& aId, const uint64_t& aSerial,
+    const wr::MaybeExternalImageId& aExternalImageId) {
+  CompositorBridgeParent::LayerTreeState* state = nullptr;
+
+  StaticMonitorAutoLock lock(CompositorBridgeParent::sIndirectLayerTreesLock);
+  auto itr = CompositorBridgeParent::sIndirectLayerTrees.find(aId);
+  if (CompositorBridgeParent::sIndirectLayerTrees.end() != itr) {
+    state = &itr->second;
+  }
+
+  TextureFlags flags = aFlags;
+
+  LayersBackend actualBackend = LayersBackend::LAYERS_NONE;
+  if (!state) {
+    // The compositor was recreated, and we're receiving layers updates for a
+    // a layer manager that will soon be discarded or invalidated. We can't
+    // return null because this will mess up deserialization later and we'll
+    // kill the content process. Instead, we signal that the underlying
+    // TextureHost should not attempt to access the compositor.
+    flags |= TextureFlags::INVALID_COMPOSITOR;
+  } else if (actualBackend != LayersBackend::LAYERS_NONE &&
+             aLayersBackend != actualBackend) {
+    gfxDevCrash(gfx::LogReason::PAllocTextureBackendMismatch)
+        << "Texture backend is wrong";
+  }
+
+  return TextureHost::CreateIPDLActor(
+      this, aSharedData, std::move(aReadLock), aLayersBackend, aFlags,
+      mCompositorManager->GetContentId(), aSerial, aExternalImageId);
+}
+
+bool ContentCompositorBridgeParent::DeallocPTextureParent(
+    PTextureParent* actor) {
+  return TextureHost::DestroyIPDLActor(actor);
+}
+
+bool ContentCompositorBridgeParent::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void ContentCompositorBridgeParent::ObserveLayersUpdate(LayersId aLayersId,
+                                                        bool aActive) {
+  MOZ_ASSERT(aLayersId.IsValid());
+
+  CompositorBridgeParent::LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(aLayersId);
+  if (!state || !state->mParent) {
+    return;
+  }
+
+  Unused << state->mParent->SendObserveLayersUpdate(aLayersId, aActive);
+}
+
+}  // namespace mozilla::layers
diff --git a/gfx/layers/ipc/ContentCompositorBridgeParent.h b/gfx/layers/ipc/ContentCompositorBridgeParent.h
new file mode 100644
index 0000000000..2425b33c7b
--- /dev/null
+++ b/gfx/layers/ipc/ContentCompositorBridgeParent.h
@@ -0,0 +1,175 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_ContentCompositorBridgeParent_h
+#define mozilla_layers_ContentCompositorBridgeParent_h
+
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/UniquePtr.h"
+
+namespace mozilla::layers {
+
+class CompositorOptions;
+
+/**
+ * This class handles layer updates pushed directly from child processes to
+ * the compositor thread. It's associated with a CompositorBridgeParent on the
+ * compositor thread. While it uses the PCompositorBridge protocol to manage
+ * these updates, it doesn't actually drive compositing itself. For that it
+ * hands off work to the CompositorBridgeParent it's associated with.
+ */
+class ContentCompositorBridgeParent final : public CompositorBridgeParentBase {
+  friend class CompositorBridgeParent;
+
+ public:
+  explicit ContentCompositorBridgeParent(CompositorManagerParent* aManager)
+      : CompositorBridgeParentBase(aManager), mDestroyCalled(false) {}
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // FIXME/bug 774388: work out what shutdown protocol we need.
+  mozilla::ipc::IPCResult RecvInitialize(
+      const LayersId& aRootLayerTreeId) override {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  mozilla::ipc::IPCResult RecvWillClose() override { return IPC_OK(); }
+  mozilla::ipc::IPCResult RecvPause() override { return IPC_OK(); }
+  mozilla::ipc::IPCResult RecvRequestFxrOutput() override {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  mozilla::ipc::IPCResult RecvResume() override { return IPC_OK(); }
+  mozilla::ipc::IPCResult RecvResumeAsync() override { return IPC_OK(); }
+  mozilla::ipc::IPCResult RecvNotifyChildCreated(
+      const LayersId& child, CompositorOptions* aOptions) override;
+  mozilla::ipc::IPCResult RecvMapAndNotifyChildCreated(
+      const LayersId& child, const base::ProcessId& pid,
+      CompositorOptions* aOptions) override;
+  mozilla::ipc::IPCResult RecvNotifyChildRecreated(
+      const LayersId& child, CompositorOptions* aOptions) override {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  mozilla::ipc::IPCResult RecvAdoptChild(const LayersId& child) override {
+    return IPC_FAIL_NO_REASON(this);
+  }
+  mozilla::ipc::IPCResult RecvFlushRendering(
+      const wr::RenderReasons&) override {
+    return IPC_OK();
+  }
+  mozilla::ipc::IPCResult RecvFlushRenderingAsync(
+      const wr::RenderReasons&) override {
+    return IPC_OK();
+  }
+  mozilla::ipc::IPCResult RecvForcePresent(const wr::RenderReasons&) override {
+    return IPC_OK();
+  }
+  mozilla::ipc::IPCResult RecvWaitOnTransactionProcessed() override {
+    return IPC_OK();
+  }
+  mozilla::ipc::IPCResult RecvStartFrameTimeRecording(
+      const int32_t& aBufferSize, uint32_t* aOutStartIndex) override {
+    return IPC_OK();
+  }
+  mozilla::ipc::IPCResult RecvStopFrameTimeRecording(
+      const uint32_t& aStartIndex, nsTArray<float>* intervals) override {
+    return IPC_OK();
+  }
+
+  mozilla::ipc::IPCResult RecvNotifyMemoryPressure() override;
+
+  mozilla::ipc::IPCResult RecvCheckContentOnlyTDR(
+      const uint32_t& sequenceNum, bool* isContentOnlyTDR) override;
+
+  mozilla::ipc::IPCResult RecvBeginRecording(
+      const TimeStamp& aRecordingStart,
+      BeginRecordingResolver&& aResolve) override {
+    aResolve(false);
+    return IPC_OK();
+  }
+
+  mozilla::ipc::IPCResult RecvEndRecording(
+      EndRecordingResolver&& aResolve) override {
+    aResolve(Nothing());
+    return IPC_OK();
+  }
+
+  bool SetTestSampleTime(const LayersId& aId, const TimeStamp& aTime) override;
+  void LeaveTestMode(const LayersId& aId) override;
+  void SetTestAsyncScrollOffset(const LayersId& aLayersId,
+                                const ScrollableLayerGuid::ViewID& aScrollId,
+                                const CSSPoint& aPoint) override;
+  void SetTestAsyncZoom(const LayersId& aLayersId,
+                        const ScrollableLayerGuid::ViewID& aScrollId,
+                        const LayerToParentLayerScale& aZoom) override;
+  void FlushApzRepaints(const LayersId& aLayersId) override;
+  void GetAPZTestData(const LayersId& aLayersId,
+                      APZTestData* aOutData) override;
+  void GetFrameUniformity(const LayersId& aLayersId,
+                          FrameUniformityData* aOutData) override;
+  void SetConfirmedTargetAPZC(
+      const LayersId& aLayersId, const uint64_t& aInputBlockId,
+      nsTArray<ScrollableLayerGuid>&& aTargets) override;
+
+  // Use DidCompositeLocked if you already hold a lock on
+  // sIndirectLayerTreesLock; Otherwise use DidComposite, which would request
+  // the lock automatically.
+  void DidCompositeLocked(LayersId aId, const VsyncId& aVsyncId,
+                          TimeStamp& aCompositeStart, TimeStamp& aCompositeEnd);
+
+  PTextureParent* AllocPTextureParent(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+      const LayersId& aId, const uint64_t& aSerial,
+      const wr::MaybeExternalImageId& aExternalImageId) override;
+
+  bool DeallocPTextureParent(PTextureParent* actor) override;
+
+  bool IsSameProcess() const override;
+
+  PCompositorWidgetParent* AllocPCompositorWidgetParent(
+      const CompositorWidgetInitData& aInitData) override {
+    // Not allowed.
+    return nullptr;
+  }
+  bool DeallocPCompositorWidgetParent(
+      PCompositorWidgetParent* aActor) override {
+    // Not allowed.
+    return false;
+  }
+
+  PAPZCTreeManagerParent* AllocPAPZCTreeManagerParent(
+      const LayersId& aLayersId) override;
+  bool DeallocPAPZCTreeManagerParent(PAPZCTreeManagerParent* aActor) override;
+
+  PAPZParent* AllocPAPZParent(const LayersId& aLayersId) override;
+  bool DeallocPAPZParent(PAPZParent* aActor) override;
+
+  PWebRenderBridgeParent* AllocPWebRenderBridgeParent(
+      const wr::PipelineId& aPipelineId, const LayoutDeviceIntSize& aSize,
+      const WindowKind& aWindowKind) override;
+  bool DeallocPWebRenderBridgeParent(PWebRenderBridgeParent* aActor) override;
+
+  void ObserveLayersUpdate(LayersId aLayersId, bool aActive) override;
+
+  bool IsRemote() const override { return true; }
+
+ private:
+  // Private destructor, to discourage deletion outside of Release():
+  virtual ~ContentCompositorBridgeParent();
+
+  void DeferredDestroy();
+
+  // There can be many CPCPs, and IPDL-generated code doesn't hold a
+  // reference to top-level actors.  So we hold a reference to
+  // ourself.  This is released (deferred) in ActorDestroy().
+  RefPtr<ContentCompositorBridgeParent> mSelfRef;
+
+  bool mDestroyCalled;
+};
+
+}  // namespace mozilla::layers
+
+#endif  // mozilla_layers_ContentCompositorBridgeParent_h
diff --git a/gfx/layers/ipc/ISurfaceAllocator.cpp b/gfx/layers/ipc/ISurfaceAllocator.cpp
new file mode 100644
index 0000000000..9e3a66f977
--- /dev/null
+++ b/gfx/layers/ipc/ISurfaceAllocator.cpp
@@ -0,0 +1,222 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ISurfaceAllocator.h"
+
+#include "mozilla/layers/ImageBridgeParent.h"  // for ImageBridgeParent
+#include "mozilla/layers/TextureHost.h"        // for TextureHost
+#include "mozilla/layers/TextureForwarder.h"
+#include "mozilla/layers/CompositableForwarder.h"
+
+namespace mozilla {
+namespace layers {
+
+NS_IMPL_ISUPPORTS(GfxMemoryImageReporter, nsIMemoryReporter)
+
+mozilla::Atomic<ptrdiff_t> GfxMemoryImageReporter::sAmount(0);
+
+void HostIPCAllocator::SendPendingAsyncMessages() {
+  if (mPendingAsyncMessage.empty()) {
+    return;
+  }
+
+  // Some type of AsyncParentMessageData message could have
+  // one file descriptor (e.g. OpDeliverFence).
+  // A number of file descriptors per gecko ipc message have a limitation
+  // on XP_UNIX (MACOSX or LINUX).
+  static const uint32_t kMaxMessageNumber =
+      IPC::Message::MAX_DESCRIPTORS_PER_MESSAGE;
+
+  nsTArray<AsyncParentMessageData> messages;
+  messages.SetCapacity(mPendingAsyncMessage.size());
+  for (size_t i = 0; i < mPendingAsyncMessage.size(); i++) {
+    messages.AppendElement(mPendingAsyncMessage[i]);
+    // Limit maximum number of messages.
+    if (messages.Length() >= kMaxMessageNumber) {
+      SendAsyncMessage(messages);
+      // Initialize Messages.
+      messages.Clear();
+    }
+  }
+
+  if (messages.Length() > 0) {
+    SendAsyncMessage(messages);
+  }
+  mPendingAsyncMessage.clear();
+}
+
+// XXX - We should actually figure out the minimum shmem allocation size on
+// a certain platform and use that.
+const uint32_t sShmemPageSize = 4096;
+
+#ifdef DEBUG
+const uint32_t sSupportedBlockSize = 4;
+#endif
+
+FixedSizeSmallShmemSectionAllocator::FixedSizeSmallShmemSectionAllocator(
+    LayersIPCChannel* aShmProvider)
+    : mShmProvider(aShmProvider) {
+  MOZ_ASSERT(mShmProvider);
+}
+
+FixedSizeSmallShmemSectionAllocator::~FixedSizeSmallShmemSectionAllocator() {
+  ShrinkShmemSectionHeap();
+}
+
+bool FixedSizeSmallShmemSectionAllocator::IPCOpen() const {
+  return mShmProvider->IPCOpen();
+}
+
+bool FixedSizeSmallShmemSectionAllocator::AllocShmemSection(
+    uint32_t aSize, ShmemSection* aShmemSection) {
+  // For now we only support sizes of 4. If we want to support different sizes
+  // some more complicated bookkeeping should be added.
+  NS_ASSERT_OWNINGTHREAD(FixedSizeSmallShmemSectionAllocator);
+  MOZ_ASSERT(aSize == sSupportedBlockSize);
+  MOZ_ASSERT(aShmemSection);
+
+  if (!IPCOpen()) {
+    gfxCriticalError() << "Attempt to allocate a ShmemSection after shutdown.";
+    return false;
+  }
+
+  uint32_t allocationSize = (aSize + sizeof(ShmemSectionHeapAllocation));
+
+  for (size_t i = 0; i < mUsedShmems.size(); i++) {
+    ShmemSectionHeapHeader* header =
+        mUsedShmems[i].get<ShmemSectionHeapHeader>();
+    if ((header->mAllocatedBlocks + 1) * allocationSize +
+            sizeof(ShmemSectionHeapHeader) <
+        sShmemPageSize) {
+      aShmemSection->shmem() = mUsedShmems[i];
+      MOZ_ASSERT(mUsedShmems[i].IsWritable());
+      break;
+    }
+  }
+
+  if (!aShmemSection->shmem().IsWritable()) {
+    ipc::Shmem tmp;
+    if (!mShmProvider->AllocUnsafeShmem(sShmemPageSize, &tmp)) {
+      return false;
+    }
+
+    ShmemSectionHeapHeader* header = tmp.get<ShmemSectionHeapHeader>();
+    header->mTotalBlocks = 0;
+    header->mAllocatedBlocks = 0;
+
+    mUsedShmems.push_back(tmp);
+    aShmemSection->shmem() = tmp;
+  }
+
+  MOZ_ASSERT(aShmemSection->shmem().IsWritable());
+
+  ShmemSectionHeapHeader* header =
+      aShmemSection->shmem().get<ShmemSectionHeapHeader>();
+  uint8_t* heap =
+      aShmemSection->shmem().get<uint8_t>() + sizeof(ShmemSectionHeapHeader);
+
+  ShmemSectionHeapAllocation* allocHeader = nullptr;
+
+  if (header->mTotalBlocks > header->mAllocatedBlocks) {
+    // Search for the first available block.
+    for (size_t i = 0; i < header->mTotalBlocks; i++) {
+      allocHeader = reinterpret_cast<ShmemSectionHeapAllocation*>(heap);
+
+      if (allocHeader->mStatus == STATUS_FREED) {
+        break;
+      }
+      heap += allocationSize;
+    }
+    MOZ_ASSERT(allocHeader && allocHeader->mStatus == STATUS_FREED);
+    MOZ_ASSERT(allocHeader->mSize == sSupportedBlockSize);
+  } else {
+    heap += header->mTotalBlocks * allocationSize;
+
+    header->mTotalBlocks++;
+    allocHeader = reinterpret_cast<ShmemSectionHeapAllocation*>(heap);
+    allocHeader->mSize = aSize;
+  }
+
+  MOZ_ASSERT(allocHeader);
+  header->mAllocatedBlocks++;
+  allocHeader->mStatus = STATUS_ALLOCATED;
+
+  aShmemSection->size() = aSize;
+  aShmemSection->offset() = (heap + sizeof(ShmemSectionHeapAllocation)) -
+                            aShmemSection->shmem().get<uint8_t>();
+  ShrinkShmemSectionHeap();
+  return true;
+}
+
+void FixedSizeSmallShmemSectionAllocator::FreeShmemSection(
+    mozilla::layers::ShmemSection& aShmemSection) {
+  MOZ_ASSERT(aShmemSection.size() == sSupportedBlockSize);
+  MOZ_ASSERT(aShmemSection.offset() < sShmemPageSize - sSupportedBlockSize);
+
+  if (!aShmemSection.shmem().IsWritable()) {
+    return;
+  }
+
+  ShmemSectionHeapAllocation* allocHeader =
+      reinterpret_cast<ShmemSectionHeapAllocation*>(
+          aShmemSection.shmem().get<char>() + aShmemSection.offset() -
+          sizeof(ShmemSectionHeapAllocation));
+
+  MOZ_ASSERT(allocHeader->mSize == aShmemSection.size());
+
+  DebugOnly<bool> success =
+      allocHeader->mStatus.compareExchange(STATUS_ALLOCATED, STATUS_FREED);
+  // If this fails something really weird is going on.
+  MOZ_ASSERT(success);
+
+  ShmemSectionHeapHeader* header =
+      aShmemSection.shmem().get<ShmemSectionHeapHeader>();
+  header->mAllocatedBlocks--;
+}
+
+void FixedSizeSmallShmemSectionAllocator::DeallocShmemSection(
+    mozilla::layers::ShmemSection& aShmemSection) {
+  NS_ASSERT_OWNINGTHREAD(FixedSizeSmallShmemSectionAllocator);
+
+  if (!IPCOpen()) {
+    gfxCriticalNote << "Attempt to dealloc a ShmemSections after shutdown.";
+    return;
+  }
+
+  FreeShmemSection(aShmemSection);
+  ShrinkShmemSectionHeap();
+}
+
+void FixedSizeSmallShmemSectionAllocator::ShrinkShmemSectionHeap() {
+  NS_ASSERT_OWNINGTHREAD(FixedSizeSmallShmemSectionAllocator);
+
+  if (!IPCOpen()) {
+    mUsedShmems.clear();
+    return;
+  }
+
+  // The loop will terminate as we either increase i, or decrease size
+  // every time through.
+  size_t i = 0;
+  while (i < mUsedShmems.size()) {
+    ShmemSectionHeapHeader* header =
+        mUsedShmems[i].get<ShmemSectionHeapHeader>();
+    if (header->mAllocatedBlocks == 0) {
+      mShmProvider->DeallocShmem(mUsedShmems[i]);
+      // We don't particularly care about order, move the last one in the array
+      // to this position.
+      if (i < mUsedShmems.size() - 1) {
+        mUsedShmems[i] = mUsedShmems[mUsedShmems.size() - 1];
+      }
+      mUsedShmems.pop_back();
+    } else {
+      i++;
+    }
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/ISurfaceAllocator.h b/gfx/layers/ipc/ISurfaceAllocator.h
new file mode 100644
index 0000000000..7faa3aeab9
--- /dev/null
+++ b/gfx/layers/ipc/ISurfaceAllocator.h
@@ -0,0 +1,287 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef GFX_LAYERS_ISURFACEDEALLOCATOR
+#define GFX_LAYERS_ISURFACEDEALLOCATOR
+
+#include <stddef.h>  // for size_t
+#include <stdint.h>  // for uint32_t
+#include "gfxTypes.h"
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/gfx/Point.h"         // for IntSize
+#include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
+#include "mozilla/RefPtr.h"
+#include "nsIMemoryReporter.h"              // for nsIMemoryReporter
+#include "mozilla/Atomics.h"                // for Atomic
+#include "mozilla/layers/LayersMessages.h"  // for ShmemSection
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+class IShmemAllocator;
+}  // namespace ipc
+namespace gfx {
+class DataSourceSurface;
+}  // namespace gfx
+
+namespace layers {
+
+class CompositableForwarder;
+class CompositorBridgeParentBase;
+class TextureForwarder;
+
+class ShmemSectionAllocator;
+class LegacySurfaceDescriptorAllocator;
+class ClientIPCAllocator;
+class HostIPCAllocator;
+class LayersIPCChannel;
+
+enum BufferCapabilities {
+  DEFAULT_BUFFER_CAPS = 0,
+  /**
+   * The allocated buffer must be efficiently mappable as a DataSourceSurface.
+   */
+  MAP_AS_IMAGE_SURFACE = 1 << 0,
+  /**
+   * The allocated buffer will be used for GL rendering only
+   */
+  USING_GL_RENDERING_ONLY = 1 << 1
+};
+
+class SurfaceDescriptor;
+
+/**
+ * An interface used to create and destroy surfaces that are shared with the
+ * Compositor process (using shmem, or other platform specific memory)
+ *
+ * Most of the methods here correspond to methods that are implemented by IPDL
+ * actors without a common polymorphic interface.
+ * These methods should be only called in the ipdl implementor's thread, unless
+ * specified otherwise in the implementing class.
+ */
+class ISurfaceAllocator {
+ public:
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(ISurfaceAllocator)
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ISurfaceAllocator)
+
+  ISurfaceAllocator() = default;
+
+  // down-casting
+
+  virtual mozilla::ipc::IShmemAllocator* AsShmemAllocator() { return nullptr; }
+
+  virtual ShmemSectionAllocator* AsShmemSectionAllocator() { return nullptr; }
+
+  virtual CompositableForwarder* AsCompositableForwarder() { return nullptr; }
+
+  virtual TextureForwarder* GetTextureForwarder() { return nullptr; }
+
+  virtual ClientIPCAllocator* AsClientAllocator() { return nullptr; }
+
+  virtual HostIPCAllocator* AsHostIPCAllocator() { return nullptr; }
+
+  virtual LegacySurfaceDescriptorAllocator*
+  AsLegacySurfaceDescriptorAllocator() {
+    return nullptr;
+  }
+
+  virtual CompositorBridgeParentBase* AsCompositorBridgeParentBase() {
+    return nullptr;
+  }
+
+  // ipc info
+
+  virtual bool IPCOpen() const { return true; }
+
+  virtual bool IsSameProcess() const = 0;
+
+  virtual bool UsesImageBridge() const { return false; }
+
+  virtual bool UsesWebRenderBridge() const { return false; }
+
+  virtual dom::ContentParentId GetContentId() { return dom::ContentParentId(); }
+
+ protected:
+  void Finalize() {}
+
+  virtual ~ISurfaceAllocator() = default;
+};
+
+/// Methods that are specific to the client/child side.
+class ClientIPCAllocator : public ISurfaceAllocator {
+ public:
+  ClientIPCAllocator() = default;
+
+  ClientIPCAllocator* AsClientAllocator() override { return this; }
+
+  virtual base::ProcessId GetParentPid() const = 0;
+
+  virtual MessageLoop* GetMessageLoop() const = 0;
+
+  virtual void CancelWaitForNotifyNotUsed(uint64_t aTextureId) = 0;
+};
+
+/// Methods that are specific to the host/parent side.
+class HostIPCAllocator : public ISurfaceAllocator {
+ public:
+  HostIPCAllocator() = default;
+
+  HostIPCAllocator* AsHostIPCAllocator() override { return this; }
+
+  /**
+   * Get child side's process Id.
+   */
+  virtual base::ProcessId GetChildProcessId() = 0;
+
+  virtual void NotifyNotUsed(PTextureParent* aTexture,
+                             uint64_t aTransactionId) = 0;
+
+  virtual void SendAsyncMessage(
+      const nsTArray<AsyncParentMessageData>& aMessage) = 0;
+
+  virtual void SendPendingAsyncMessages();
+
+  virtual void SetAboutToSendAsyncMessages() {
+    mAboutToSendAsyncMessages = true;
+  }
+
+  bool IsAboutToSendAsyncMessages() { return mAboutToSendAsyncMessages; }
+
+ protected:
+  std::vector<AsyncParentMessageData> mPendingAsyncMessage;
+  bool mAboutToSendAsyncMessages = false;
+};
+
+/// An allocator that can group allocations in bigger chunks of shared memory.
+///
+/// The allocated shmem sections can only be deallocated by the same allocator
+/// instance (and only in the child process).
+class ShmemSectionAllocator {
+ public:
+  virtual bool AllocShmemSection(uint32_t aSize,
+                                 ShmemSection* aShmemSection) = 0;
+
+  virtual void DeallocShmemSection(ShmemSection& aShmemSection) = 0;
+
+  virtual void MemoryPressure() {}
+};
+
+/// Some old stuff that's still around and used for screenshots.
+///
+/// New code should not need this (see TextureClient).
+class LegacySurfaceDescriptorAllocator {
+ public:
+  virtual bool AllocSurfaceDescriptor(const gfx::IntSize& aSize,
+                                      gfxContentType aContent,
+                                      SurfaceDescriptor* aBuffer) = 0;
+
+  virtual bool AllocSurfaceDescriptorWithCaps(const gfx::IntSize& aSize,
+                                              gfxContentType aContent,
+                                              uint32_t aCaps,
+                                              SurfaceDescriptor* aBuffer) = 0;
+
+  virtual void DestroySurfaceDescriptor(SurfaceDescriptor* aSurface) = 0;
+};
+
+bool IsSurfaceDescriptorValid(const SurfaceDescriptor& aSurface);
+
+already_AddRefed<gfx::DataSourceSurface> GetSurfaceForDescriptor(
+    const SurfaceDescriptor& aDescriptor);
+
+uint8_t* GetAddressFromDescriptor(const SurfaceDescriptor& aDescriptor);
+
+void DestroySurfaceDescriptor(mozilla::ipc::IShmemAllocator* aAllocator,
+                              SurfaceDescriptor* aSurface);
+
+class GfxMemoryImageReporter final : public nsIMemoryReporter {
+  ~GfxMemoryImageReporter() = default;
+
+ public:
+  NS_DECL_ISUPPORTS
+
+  GfxMemoryImageReporter() {
+#ifdef DEBUG
+    // There must be only one instance of this class, due to |sAmount|
+    // being static.
+    static bool hasRun = false;
+    MOZ_ASSERT(!hasRun);
+    hasRun = true;
+#endif
+  }
+
+  MOZ_DEFINE_MALLOC_SIZE_OF_ON_ALLOC(MallocSizeOfOnAlloc)
+  MOZ_DEFINE_MALLOC_SIZE_OF_ON_FREE(MallocSizeOfOnFree)
+
+  static void DidAlloc(void* aPointer) {
+    sAmount += MallocSizeOfOnAlloc(aPointer);
+  }
+
+  static void WillFree(void* aPointer) {
+    sAmount -= MallocSizeOfOnFree(aPointer);
+  }
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override {
+    MOZ_COLLECT_REPORT(
+        "explicit/gfx/heap-textures", KIND_HEAP, UNITS_BYTES, sAmount,
+        "Heap memory shared between threads by texture clients and hosts.");
+
+    return NS_OK;
+  }
+
+ private:
+  // Typically we use |size_t| in memory reporters, but in the past this
+  // variable has sometimes gone negative due to missing DidAlloc() calls.
+  // Therefore, we use a signed type so that any such negative values show up
+  // as negative in about:memory, rather than as enormous positive numbers.
+  static mozilla::Atomic<ptrdiff_t> sAmount;
+};
+
+/// A simple shmem section allocator that can only allocate small
+/// fixed size elements (only intended to be used to store tile
+/// copy-on-write locks for now).
+class FixedSizeSmallShmemSectionAllocator final : public ShmemSectionAllocator {
+ public:
+  NS_DECL_OWNINGTHREAD
+
+  enum AllocationStatus { STATUS_ALLOCATED, STATUS_FREED };
+
+  struct ShmemSectionHeapHeader {
+    Atomic<uint32_t> mTotalBlocks;
+    Atomic<uint32_t> mAllocatedBlocks;
+  };
+
+  struct ShmemSectionHeapAllocation {
+    Atomic<uint32_t> mStatus;
+    uint32_t mSize;
+  };
+
+  explicit FixedSizeSmallShmemSectionAllocator(LayersIPCChannel* aShmProvider);
+
+  ~FixedSizeSmallShmemSectionAllocator();
+
+  bool AllocShmemSection(uint32_t aSize, ShmemSection* aShmemSection) override;
+
+  void DeallocShmemSection(ShmemSection& aShmemSection) override;
+
+  void MemoryPressure() override { ShrinkShmemSectionHeap(); }
+
+  // can be called on the compositor process.
+  static void FreeShmemSection(ShmemSection& aShmemSection);
+
+  void ShrinkShmemSectionHeap();
+
+  bool IPCOpen() const;
+
+ protected:
+  std::vector<mozilla::ipc::Shmem> mUsedShmems;
+  LayersIPCChannel* mShmProvider;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/ImageBridgeChild.cpp b/gfx/layers/ipc/ImageBridgeChild.cpp
new file mode 100644
index 0000000000..32489afabd
--- /dev/null
+++ b/gfx/layers/ipc/ImageBridgeChild.cpp
@@ -0,0 +1,975 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImageBridgeChild.h"
+
+#include <vector>  // for vector
+
+#include "ImageBridgeParent.h"  // for ImageBridgeParent
+#include "ImageContainer.h"     // for ImageContainer
+#include "SynchronousTask.h"
+#include "mozilla/Assertions.h"        // for MOZ_ASSERT, etc
+#include "mozilla/Monitor.h"           // for Monitor, MonitorAutoLock
+#include "mozilla/ReentrantMonitor.h"  // for ReentrantMonitor, etc
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"  // for StaticRefPtr
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/gfx/Point.h"  // for IntSize
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/ipc/MessageChannel.h"         // for MessageChannel, etc
+#include "mozilla/layers/CompositableClient.h"  // for CompositableChild, etc
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/ISurfaceAllocator.h"  // for ISurfaceAllocator
+#include "mozilla/layers/ImageClient.h"        // for ImageClient
+#include "mozilla/layers/LayersMessages.h"     // for CompositableOperation
+#include "mozilla/layers/TextureClient.h"      // for TextureClient
+#include "mozilla/layers/TextureClient.h"
+#include "mozilla/media/MediaSystemResourceManager.h"  // for MediaSystemResourceManager
+#include "mozilla/media/MediaSystemResourceManagerChild.h"  // for MediaSystemResourceManagerChild
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "transport/runnable_utils.h"
+#include "nsContentUtils.h"
+#include "nsGlobalWindowInner.h"
+#include "nsISupportsImpl.h"         // for ImageContainer::AddRef, etc
+#include "nsTArray.h"                // for AutoTArray, nsTArray, etc
+#include "nsTArrayForwardDeclare.h"  // for AutoTArray
+#include "nsThreadUtils.h"           // for NS_IsMainThread
+#include "WindowRenderer.h"
+
+#if defined(XP_WIN)
+#  include "mozilla/gfx/DeviceManagerDx.h"
+#endif
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+}  // namespace ipc
+
+namespace layers {
+
+using namespace mozilla::ipc;
+using namespace mozilla::gfx;
+using namespace mozilla::media;
+
+typedef std::vector<CompositableOperation> OpVector;
+typedef nsTArray<OpDestroy> OpDestroyVector;
+
+struct CompositableTransaction {
+  CompositableTransaction() : mFinished(true) {}
+  ~CompositableTransaction() { End(); }
+  bool Finished() const { return mFinished; }
+  void Begin() {
+    MOZ_ASSERT(mFinished);
+    mFinished = false;
+  }
+  void End() {
+    mFinished = true;
+    mOperations.clear();
+    mDestroyedActors.Clear();
+  }
+  bool IsEmpty() const {
+    return mOperations.empty() && mDestroyedActors.IsEmpty();
+  }
+  void AddNoSwapEdit(const CompositableOperation& op) {
+    MOZ_ASSERT(!Finished(), "forgot BeginTransaction?");
+    mOperations.push_back(op);
+  }
+
+  OpVector mOperations;
+  OpDestroyVector mDestroyedActors;
+
+  bool mFinished;
+};
+
+struct AutoEndTransaction final {
+  explicit AutoEndTransaction(CompositableTransaction* aTxn) : mTxn(aTxn) {}
+  ~AutoEndTransaction() { mTxn->End(); }
+  CompositableTransaction* mTxn;
+};
+
+void ImageBridgeChild::UseTextures(
+    CompositableClient* aCompositable,
+    const nsTArray<TimedTextureClient>& aTextures) {
+  MOZ_ASSERT(aCompositable);
+  MOZ_ASSERT(aCompositable->GetIPCHandle());
+  MOZ_ASSERT(aCompositable->IsConnected());
+
+  AutoTArray<TimedTexture, 4> textures;
+
+  for (auto& t : aTextures) {
+    MOZ_ASSERT(t.mTextureClient);
+    MOZ_ASSERT(t.mTextureClient->GetIPDLActor());
+
+    if (!t.mTextureClient->IsSharedWithCompositor()) {
+      return;
+    }
+
+    bool readLocked = t.mTextureClient->OnForwardedToHost();
+
+    textures.AppendElement(TimedTexture(
+        WrapNotNull(t.mTextureClient->GetIPDLActor()), t.mTimeStamp,
+        t.mPictureRect, t.mFrameID, t.mProducerID, readLocked));
+
+    // Wait end of usage on host side if TextureFlags::RECYCLE is set
+    HoldUntilCompositableRefReleasedIfNecessary(t.mTextureClient);
+  }
+  mTxn->AddNoSwapEdit(CompositableOperation(aCompositable->GetIPCHandle(),
+                                            OpUseTexture(textures)));
+}
+
+void ImageBridgeChild::UseRemoteTexture(
+    CompositableClient* aCompositable, const RemoteTextureId aTextureId,
+    const RemoteTextureOwnerId aOwnerId, const gfx::IntSize aSize,
+    const TextureFlags aFlags, const RefPtr<FwdTransactionTracker>& aTracker) {
+  MOZ_ASSERT(aCompositable);
+  MOZ_ASSERT(aCompositable->GetIPCHandle());
+  MOZ_ASSERT(aCompositable->IsConnected());
+
+  mTxn->AddNoSwapEdit(CompositableOperation(
+      aCompositable->GetIPCHandle(),
+      OpUseRemoteTexture(aTextureId, aOwnerId, aSize, aFlags)));
+  TrackFwdTransaction(aTracker);
+}
+
+void ImageBridgeChild::HoldUntilCompositableRefReleasedIfNecessary(
+    TextureClient* aClient) {
+  if (!aClient) {
+    return;
+  }
+
+  // Wait ReleaseCompositableRef only when TextureFlags::RECYCLE or
+  // TextureFlags::WAIT_HOST_USAGE_END is set on ImageBridge.
+  bool waitNotifyNotUsed =
+      aClient->GetFlags() & TextureFlags::RECYCLE ||
+      aClient->GetFlags() & TextureFlags::WAIT_HOST_USAGE_END;
+  if (!waitNotifyNotUsed) {
+    return;
+  }
+
+  aClient->SetLastFwdTransactionId(GetFwdTransactionId());
+  mTexturesWaitingNotifyNotUsed.emplace(aClient->GetSerial(), aClient);
+}
+
+void ImageBridgeChild::NotifyNotUsed(uint64_t aTextureId,
+                                     uint64_t aFwdTransactionId) {
+  auto it = mTexturesWaitingNotifyNotUsed.find(aTextureId);
+  if (it != mTexturesWaitingNotifyNotUsed.end()) {
+    if (aFwdTransactionId < it->second->GetLastFwdTransactionId()) {
+      // Released on host side, but client already requested newer use texture.
+      return;
+    }
+    mTexturesWaitingNotifyNotUsed.erase(it);
+  }
+}
+
+void ImageBridgeChild::CancelWaitForNotifyNotUsed(uint64_t aTextureId) {
+  MOZ_ASSERT(InImageBridgeChildThread());
+  mTexturesWaitingNotifyNotUsed.erase(aTextureId);
+}
+
+// Singleton
+static StaticMutex sImageBridgeSingletonLock MOZ_UNANNOTATED;
+static StaticRefPtr<ImageBridgeChild> sImageBridgeChildSingleton;
+static StaticRefPtr<nsIThread> sImageBridgeChildThread;
+
+// dispatched function
+void ImageBridgeChild::ShutdownStep1(SynchronousTask* aTask) {
+  AutoCompleteTask complete(aTask);
+
+  MOZ_ASSERT(InImageBridgeChildThread(),
+             "Should be in ImageBridgeChild thread.");
+
+  MediaSystemResourceManager::Shutdown();
+
+  // Force all managed protocols to shut themselves down cleanly
+  nsTArray<PTextureChild*> textures;
+  ManagedPTextureChild(textures);
+  for (int i = textures.Length() - 1; i >= 0; --i) {
+    RefPtr<TextureClient> client = TextureClient::AsTextureClient(textures[i]);
+    if (client) {
+      client->Destroy();
+    }
+  }
+
+  if (mCanSend) {
+    SendWillClose();
+  }
+  MarkShutDown();
+
+  // From now on, no message can be sent through the image bridge from the
+  // client side except the final Stop message.
+}
+
+// dispatched function
+void ImageBridgeChild::ShutdownStep2(SynchronousTask* aTask) {
+  AutoCompleteTask complete(aTask);
+
+  MOZ_ASSERT(InImageBridgeChildThread(),
+             "Should be in ImageBridgeChild thread.");
+
+  mSectionAllocator = nullptr;
+
+  if (!mDestroyed) {
+    Close();
+  }
+}
+
+void ImageBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mCanSend = false;
+  mDestroyed = true;
+  {
+    MutexAutoLock lock(mContainerMapLock);
+    mImageContainerListeners.clear();
+  }
+}
+
+void ImageBridgeChild::CreateImageClientSync(SynchronousTask* aTask,
+                                             RefPtr<ImageClient>* result,
+                                             CompositableType aType,
+                                             ImageContainer* aImageContainer) {
+  AutoCompleteTask complete(aTask);
+  *result = CreateImageClientNow(aType, aImageContainer);
+}
+
+ImageBridgeChild::ImageBridgeChild(uint32_t aNamespace)
+    : mNamespace(aNamespace),
+      mCanSend(false),
+      mDestroyed(false),
+      mFwdTransactionCounter(this),
+      mContainerMapLock("ImageBridgeChild.mContainerMapLock") {
+  MOZ_ASSERT(mNamespace);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  mTxn = new CompositableTransaction();
+}
+
+ImageBridgeChild::~ImageBridgeChild() { delete mTxn; }
+
+void ImageBridgeChild::MarkShutDown() {
+  mTexturesWaitingNotifyNotUsed.clear();
+
+  mCanSend = false;
+}
+
+void ImageBridgeChild::Connect(CompositableClient* aCompositable,
+                               ImageContainer* aImageContainer) {
+  MOZ_ASSERT(aCompositable);
+  MOZ_ASSERT(InImageBridgeChildThread());
+  MOZ_ASSERT(CanSend());
+
+  CompositableHandle handle = CompositableHandle::GetNext();
+
+  // ImageClient of ImageContainer provides aImageContainer.
+  // But offscreen canvas does not provide it.
+  if (aImageContainer) {
+    MutexAutoLock lock(mContainerMapLock);
+    MOZ_ASSERT(mImageContainerListeners.find(uint64_t(handle)) ==
+               mImageContainerListeners.end());
+    mImageContainerListeners.emplace(
+        uint64_t(handle), aImageContainer->GetImageContainerListener());
+  }
+
+  aCompositable->InitIPDL(handle);
+  SendNewCompositable(handle, aCompositable->GetTextureInfo());
+}
+
+void ImageBridgeChild::ForgetImageContainer(const CompositableHandle& aHandle) {
+  MutexAutoLock lock(mContainerMapLock);
+  mImageContainerListeners.erase(aHandle.Value());
+}
+
+/* static */
+RefPtr<ImageBridgeChild> ImageBridgeChild::GetSingleton() {
+  StaticMutexAutoLock lock(sImageBridgeSingletonLock);
+  return sImageBridgeChildSingleton;
+}
+
+void ImageBridgeChild::UpdateImageClient(RefPtr<ImageContainer> aContainer) {
+  if (!aContainer) {
+    return;
+  }
+
+  if (!InImageBridgeChildThread()) {
+    RefPtr<Runnable> runnable =
+        WrapRunnable(RefPtr<ImageBridgeChild>(this),
+                     &ImageBridgeChild::UpdateImageClient, aContainer);
+    GetThread()->Dispatch(runnable.forget());
+    return;
+  }
+
+  if (!CanSend()) {
+    return;
+  }
+
+  RefPtr<ImageClient> client = aContainer->GetImageClient();
+  if (NS_WARN_IF(!client)) {
+    return;
+  }
+
+  // If the client has become disconnected before this event was dispatched,
+  // early return now.
+  if (!client->IsConnected()) {
+    return;
+  }
+
+  BeginTransaction();
+  client->UpdateImage(aContainer);
+  EndTransaction();
+}
+
+void ImageBridgeChild::UpdateCompositable(
+    const RefPtr<ImageContainer> aContainer, const RemoteTextureId aTextureId,
+    const RemoteTextureOwnerId aOwnerId, const gfx::IntSize aSize,
+    const TextureFlags aFlags, const RefPtr<FwdTransactionTracker> aTracker) {
+  if (!aContainer) {
+    return;
+  }
+
+  if (!InImageBridgeChildThread()) {
+    RefPtr<Runnable> runnable = WrapRunnable(
+        RefPtr<ImageBridgeChild>(this), &ImageBridgeChild::UpdateCompositable,
+        aContainer, aTextureId, aOwnerId, aSize, aFlags, aTracker);
+    GetThread()->Dispatch(runnable.forget());
+    return;
+  }
+
+  if (!CanSend()) {
+    return;
+  }
+
+  RefPtr<ImageClient> client = aContainer->GetImageClient();
+  if (NS_WARN_IF(!client)) {
+    return;
+  }
+
+  // If the client has become disconnected before this event was dispatched,
+  // early return now.
+  if (!client->IsConnected()) {
+    return;
+  }
+
+  BeginTransaction();
+  UseRemoteTexture(client, aTextureId, aOwnerId, aSize, aFlags, aTracker);
+  EndTransaction();
+}
+
+void ImageBridgeChild::FlushAllImagesSync(SynchronousTask* aTask,
+                                          ImageClient* aClient,
+                                          ImageContainer* aContainer) {
+  AutoCompleteTask complete(aTask);
+
+  if (!CanSend()) {
+    return;
+  }
+
+  MOZ_ASSERT(aClient);
+  BeginTransaction();
+  if (aContainer) {
+    aContainer->ClearImagesFromImageBridge();
+  }
+  aClient->FlushAllImages();
+  EndTransaction();
+}
+
+void ImageBridgeChild::FlushAllImages(ImageClient* aClient,
+                                      ImageContainer* aContainer) {
+  MOZ_ASSERT(aClient);
+  MOZ_ASSERT(!InImageBridgeChildThread());
+
+  if (InImageBridgeChildThread()) {
+    NS_ERROR(
+        "ImageBridgeChild::FlushAllImages() is called on ImageBridge thread.");
+    return;
+  }
+
+  SynchronousTask task("FlushAllImages Lock");
+
+  // RefPtrs on arguments are not needed since this dispatches synchronously.
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<ImageBridgeChild>(this), &ImageBridgeChild::FlushAllImagesSync,
+      &task, aClient, aContainer);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+}
+
+void ImageBridgeChild::SyncWithCompositor(const Maybe<uint64_t>& aWindowID) {
+  if (NS_WARN_IF(InImageBridgeChildThread())) {
+    MOZ_ASSERT_UNREACHABLE("Cannot call on ImageBridge thread!");
+    return;
+  }
+
+  if (!aWindowID) {
+    return;
+  }
+
+  const auto fnSyncWithWindow = [&]() {
+    if (auto* window = nsGlobalWindowInner::GetInnerWindowWithId(*aWindowID)) {
+      if (auto* widget = window->GetNearestWidget()) {
+        if (auto* renderer = widget->GetWindowRenderer()) {
+          if (auto* kc = renderer->AsKnowsCompositor()) {
+            kc->SyncWithCompositor();
+          }
+        }
+      }
+    }
+  };
+
+  if (NS_IsMainThread()) {
+    fnSyncWithWindow();
+    return;
+  }
+
+  SynchronousTask task("SyncWithCompositor Lock");
+  RefPtr<Runnable> runnable =
+      NS_NewRunnableFunction("ImageBridgeChild::SyncWithCompositor", [&]() {
+        AutoCompleteTask complete(&task);
+        fnSyncWithWindow();
+      });
+  NS_DispatchToMainThread(runnable.forget());
+  task.Wait();
+}
+
+void ImageBridgeChild::BeginTransaction() {
+  MOZ_ASSERT(CanSend());
+  MOZ_ASSERT(mTxn->Finished(), "uncommitted txn?");
+  UpdateFwdTransactionId();
+  mTxn->Begin();
+}
+
+void ImageBridgeChild::EndTransaction() {
+  MOZ_ASSERT(CanSend());
+  MOZ_ASSERT(!mTxn->Finished(), "forgot BeginTransaction?");
+
+  AutoEndTransaction _(mTxn);
+
+  if (mTxn->IsEmpty()) {
+    return;
+  }
+
+  AutoTArray<CompositableOperation, 10> cset;
+  cset.SetCapacity(mTxn->mOperations.size());
+  if (!mTxn->mOperations.empty()) {
+    cset.AppendElements(&mTxn->mOperations.front(), mTxn->mOperations.size());
+  }
+
+  if (!SendUpdate(cset, mTxn->mDestroyedActors, GetFwdTransactionId())) {
+    NS_WARNING("could not send async texture transaction");
+    return;
+  }
+}
+
+bool ImageBridgeChild::InitForContent(Endpoint<PImageBridgeChild>&& aEndpoint,
+                                      uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  gfxPlatform::GetPlatform();
+
+  if (!sImageBridgeChildThread) {
+    nsCOMPtr<nsIThread> thread;
+    nsresult rv = NS_NewNamedThread("ImageBridgeChld", getter_AddRefs(thread));
+    MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv),
+                       "Failed to start ImageBridgeChild thread!");
+    sImageBridgeChildThread = thread.forget();
+  }
+
+  RefPtr<ImageBridgeChild> child = new ImageBridgeChild(aNamespace);
+
+  child->GetThread()->Dispatch(NS_NewRunnableFunction(
+      "layers::ImageBridgeChild::Bind",
+      [child, endpoint = std::move(aEndpoint)]() mutable {
+        child->Bind(std::move(endpoint));
+      }));
+
+  // Assign this after so other threads can't post messages before we connect to
+  // IPDL.
+  {
+    StaticMutexAutoLock lock(sImageBridgeSingletonLock);
+    sImageBridgeChildSingleton = child;
+  }
+
+  return true;
+}
+
+bool ImageBridgeChild::ReinitForContent(Endpoint<PImageBridgeChild>&& aEndpoint,
+                                        uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Note that at this point, ActorDestroy may not have been called yet,
+  // meaning mCanSend is still true. In this case we will try to send a
+  // synchronous WillClose message to the parent, and will certainly get a
+  // false result and a MsgDropped processing error. This is okay.
+  ShutdownSingleton();
+
+  return InitForContent(std::move(aEndpoint), aNamespace);
+}
+
+void ImageBridgeChild::Bind(Endpoint<PImageBridgeChild>&& aEndpoint) {
+  if (!aEndpoint.Bind(this)) {
+    return;
+  }
+
+  mSectionAllocator = MakeUnique<FixedSizeSmallShmemSectionAllocator>(this);
+  mCanSend = true;
+}
+
+void ImageBridgeChild::BindSameProcess(RefPtr<ImageBridgeParent> aParent) {
+  Open(aParent, aParent->GetThread(), mozilla::ipc::ChildSide);
+
+  mSectionAllocator = MakeUnique<FixedSizeSmallShmemSectionAllocator>(this);
+  mCanSend = true;
+}
+
+/* static */
+void ImageBridgeChild::ShutDown() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  ShutdownSingleton();
+
+  if (sImageBridgeChildThread) {
+    sImageBridgeChildThread->Shutdown();
+    sImageBridgeChildThread = nullptr;
+  }
+}
+
+/* static */
+void ImageBridgeChild::ShutdownSingleton() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (RefPtr<ImageBridgeChild> child = GetSingleton()) {
+    child->WillShutdown();
+
+    StaticMutexAutoLock lock(sImageBridgeSingletonLock);
+    sImageBridgeChildSingleton = nullptr;
+  }
+}
+
+void ImageBridgeChild::WillShutdown() {
+  {
+    SynchronousTask task("ImageBridge ShutdownStep1 lock");
+
+    RefPtr<Runnable> runnable =
+        WrapRunnable(RefPtr<ImageBridgeChild>(this),
+                     &ImageBridgeChild::ShutdownStep1, &task);
+    GetThread()->Dispatch(runnable.forget());
+
+    task.Wait();
+  }
+
+  {
+    SynchronousTask task("ImageBridge ShutdownStep2 lock");
+
+    RefPtr<Runnable> runnable =
+        WrapRunnable(RefPtr<ImageBridgeChild>(this),
+                     &ImageBridgeChild::ShutdownStep2, &task);
+    GetThread()->Dispatch(runnable.forget());
+
+    task.Wait();
+  }
+}
+
+void ImageBridgeChild::InitSameProcess(uint32_t aNamespace) {
+  NS_ASSERTION(NS_IsMainThread(), "Should be on the main Thread!");
+
+  MOZ_ASSERT(!sImageBridgeChildSingleton);
+  MOZ_ASSERT(!sImageBridgeChildThread);
+
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewNamedThread("ImageBridgeChld", getter_AddRefs(thread));
+  MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv),
+                     "Failed to start ImageBridgeChild thread!");
+  sImageBridgeChildThread = thread.forget();
+
+  RefPtr<ImageBridgeChild> child = new ImageBridgeChild(aNamespace);
+  RefPtr<ImageBridgeParent> parent = ImageBridgeParent::CreateSameProcess();
+
+  RefPtr<Runnable> runnable =
+      WrapRunnable(child, &ImageBridgeChild::BindSameProcess, parent);
+  child->GetThread()->Dispatch(runnable.forget());
+
+  // Assign this after so other threads can't post messages before we connect to
+  // IPDL.
+  {
+    StaticMutexAutoLock lock(sImageBridgeSingletonLock);
+    sImageBridgeChildSingleton = child;
+  }
+}
+
+/* static */
+void ImageBridgeChild::InitWithGPUProcess(
+    Endpoint<PImageBridgeChild>&& aEndpoint, uint32_t aNamespace) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(!sImageBridgeChildSingleton);
+  MOZ_ASSERT(!sImageBridgeChildThread);
+
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewNamedThread("ImageBridgeChld", getter_AddRefs(thread));
+  MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv),
+                     "Failed to start ImageBridgeChild thread!");
+  sImageBridgeChildThread = thread.forget();
+
+  RefPtr<ImageBridgeChild> child = new ImageBridgeChild(aNamespace);
+
+  child->GetThread()->Dispatch(NS_NewRunnableFunction(
+      "layers::ImageBridgeChild::Bind",
+      [child, endpoint = std::move(aEndpoint)]() mutable {
+        child->Bind(std::move(endpoint));
+      }));
+
+  // Assign this after so other threads can't post messages before we connect to
+  // IPDL.
+  {
+    StaticMutexAutoLock lock(sImageBridgeSingletonLock);
+    sImageBridgeChildSingleton = child;
+  }
+}
+
+bool InImageBridgeChildThread() {
+  return sImageBridgeChildThread &&
+         sImageBridgeChildThread->IsOnCurrentThread();
+}
+
+FixedSizeSmallShmemSectionAllocator* ImageBridgeChild::GetTileLockAllocator() {
+  return mSectionAllocator.get();
+}
+
+nsISerialEventTarget* ImageBridgeChild::GetThread() const {
+  return sImageBridgeChildThread;
+}
+
+/* static */
+void ImageBridgeChild::IdentifyCompositorTextureHost(
+    const TextureFactoryIdentifier& aIdentifier) {
+  if (RefPtr<ImageBridgeChild> child = GetSingleton()) {
+    child->UpdateTextureFactoryIdentifier(aIdentifier);
+  }
+}
+
+void ImageBridgeChild::UpdateTextureFactoryIdentifier(
+    const TextureFactoryIdentifier& aIdentifier) {
+  IdentifyTextureHost(aIdentifier);
+}
+
+RefPtr<ImageClient> ImageBridgeChild::CreateImageClient(
+    CompositableType aType, ImageContainer* aImageContainer) {
+  if (InImageBridgeChildThread()) {
+    return CreateImageClientNow(aType, aImageContainer);
+  }
+
+  SynchronousTask task("CreateImageClient Lock");
+
+  RefPtr<ImageClient> result = nullptr;
+
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<ImageBridgeChild>(this), &ImageBridgeChild::CreateImageClientSync,
+      &task, &result, aType, aImageContainer);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+
+  return result;
+}
+
+RefPtr<ImageClient> ImageBridgeChild::CreateImageClientNow(
+    CompositableType aType, ImageContainer* aImageContainer) {
+  MOZ_ASSERT(InImageBridgeChildThread());
+  if (!CanSend()) {
+    return nullptr;
+  }
+
+  RefPtr<ImageClient> client =
+      ImageClient::CreateImageClient(aType, this, TextureFlags::NO_FLAGS);
+  MOZ_ASSERT(client, "failed to create ImageClient");
+  if (client) {
+    client->Connect(aImageContainer);
+  }
+  return client;
+}
+
+bool ImageBridgeChild::AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) {
+  if (!InImageBridgeChildThread()) {
+    return DispatchAllocShmemInternal(aSize, aShmem,
+                                      true);  // true: unsafe
+  }
+
+  if (!CanSend()) {
+    return false;
+  }
+  return PImageBridgeChild::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool ImageBridgeChild::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  if (!InImageBridgeChildThread()) {
+    return DispatchAllocShmemInternal(aSize, aShmem,
+                                      false);  // false: unsafe
+  }
+
+  if (!CanSend()) {
+    return false;
+  }
+  return PImageBridgeChild::AllocShmem(aSize, aShmem);
+}
+
+void ImageBridgeChild::ProxyAllocShmemNow(SynchronousTask* aTask, size_t aSize,
+                                          ipc::Shmem* aShmem, bool aUnsafe,
+                                          bool* aSuccess) {
+  AutoCompleteTask complete(aTask);
+
+  if (!CanSend()) {
+    return;
+  }
+
+  bool ok = false;
+  if (aUnsafe) {
+    ok = AllocUnsafeShmem(aSize, aShmem);
+  } else {
+    ok = AllocShmem(aSize, aShmem);
+  }
+  *aSuccess = ok;
+}
+
+bool ImageBridgeChild::DispatchAllocShmemInternal(size_t aSize,
+                                                  ipc::Shmem* aShmem,
+                                                  bool aUnsafe) {
+  SynchronousTask task("AllocatorProxy alloc");
+
+  bool success = false;
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<ImageBridgeChild>(this), &ImageBridgeChild::ProxyAllocShmemNow,
+      &task, aSize, aShmem, aUnsafe, &success);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+
+  return success;
+}
+
+void ImageBridgeChild::ProxyDeallocShmemNow(SynchronousTask* aTask,
+                                            ipc::Shmem* aShmem, bool* aResult) {
+  AutoCompleteTask complete(aTask);
+
+  if (!CanSend()) {
+    return;
+  }
+  *aResult = DeallocShmem(*aShmem);
+}
+
+bool ImageBridgeChild::DeallocShmem(ipc::Shmem& aShmem) {
+  if (InImageBridgeChildThread()) {
+    if (!CanSend()) {
+      return false;
+    }
+    return PImageBridgeChild::DeallocShmem(aShmem);
+  }
+
+  // If we can't post a task, then we definitely cannot send, so there's
+  // no reason to queue up this send.
+  if (!CanPostTask()) {
+    return false;
+  }
+
+  SynchronousTask task("AllocatorProxy Dealloc");
+  bool result = false;
+
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<ImageBridgeChild>(this), &ImageBridgeChild::ProxyDeallocShmemNow,
+      &task, &aShmem, &result);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+  return result;
+}
+
+PTextureChild* ImageBridgeChild::AllocPTextureChild(
+    const SurfaceDescriptor&, ReadLockDescriptor&, const LayersBackend&,
+    const TextureFlags&, const uint64_t& aSerial,
+    const wr::MaybeExternalImageId& aExternalImageId) {
+  MOZ_ASSERT(CanSend());
+  return TextureClient::CreateIPDLActor();
+}
+
+bool ImageBridgeChild::DeallocPTextureChild(PTextureChild* actor) {
+  return TextureClient::DestroyIPDLActor(actor);
+}
+
+PMediaSystemResourceManagerChild*
+ImageBridgeChild::AllocPMediaSystemResourceManagerChild() {
+  MOZ_ASSERT(CanSend());
+  return new mozilla::media::MediaSystemResourceManagerChild();
+}
+
+bool ImageBridgeChild::DeallocPMediaSystemResourceManagerChild(
+    PMediaSystemResourceManagerChild* aActor) {
+  MOZ_ASSERT(aActor);
+  delete static_cast<mozilla::media::MediaSystemResourceManagerChild*>(aActor);
+  return true;
+}
+
+mozilla::ipc::IPCResult ImageBridgeChild::RecvParentAsyncMessages(
+    nsTArray<AsyncParentMessageData>&& aMessages) {
+  for (AsyncParentMessageArray::index_type i = 0; i < aMessages.Length(); ++i) {
+    const AsyncParentMessageData& message = aMessages[i];
+
+    switch (message.type()) {
+      case AsyncParentMessageData::TOpNotifyNotUsed: {
+        const OpNotifyNotUsed& op = message.get_OpNotifyNotUsed();
+        NotifyNotUsed(op.TextureId(), op.fwdTransactionId());
+        break;
+      }
+      default:
+        NS_ERROR("unknown AsyncParentMessageData type");
+        return IPC_FAIL_NO_REASON(this);
+    }
+  }
+  return IPC_OK();
+}
+
+RefPtr<ImageContainerListener> ImageBridgeChild::FindListener(
+    const CompositableHandle& aHandle) {
+  RefPtr<ImageContainerListener> listener;
+  MutexAutoLock lock(mContainerMapLock);
+  auto it = mImageContainerListeners.find(aHandle.Value());
+  if (it != mImageContainerListeners.end()) {
+    listener = it->second;
+  }
+  return listener;
+}
+
+mozilla::ipc::IPCResult ImageBridgeChild::RecvDidComposite(
+    nsTArray<ImageCompositeNotification>&& aNotifications) {
+  for (auto& n : aNotifications) {
+    RefPtr<ImageContainerListener> listener = FindListener(n.compositable());
+    if (listener) {
+      listener->NotifyComposite(n);
+    }
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ImageBridgeChild::RecvReportFramesDropped(
+    const CompositableHandle& aHandle, const uint32_t& aFrames) {
+  RefPtr<ImageContainerListener> listener = FindListener(aHandle);
+  if (listener) {
+    listener->NotifyDropped(aFrames);
+  }
+
+  return IPC_OK();
+}
+
+PTextureChild* ImageBridgeChild::CreateTexture(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+    LayersBackend aLayersBackend, TextureFlags aFlags,
+    const dom::ContentParentId& aContentId, uint64_t aSerial,
+    wr::MaybeExternalImageId& aExternalImageId) {
+  MOZ_ASSERT(CanSend());
+  return SendPTextureConstructor(aSharedData, std::move(aReadLock),
+                                 aLayersBackend, aFlags, aSerial,
+                                 aExternalImageId);
+}
+
+static bool IBCAddOpDestroy(CompositableTransaction* aTxn,
+                            const OpDestroy& op) {
+  if (aTxn->Finished()) {
+    return false;
+  }
+
+  aTxn->mDestroyedActors.AppendElement(op);
+  return true;
+}
+
+bool ImageBridgeChild::DestroyInTransaction(PTextureChild* aTexture) {
+  return IBCAddOpDestroy(mTxn, OpDestroy(WrapNotNull(aTexture)));
+}
+
+bool ImageBridgeChild::DestroyInTransaction(const CompositableHandle& aHandle) {
+  return IBCAddOpDestroy(mTxn, OpDestroy(aHandle));
+}
+
+void ImageBridgeChild::RemoveTextureFromCompositable(
+    CompositableClient* aCompositable, TextureClient* aTexture) {
+  MOZ_ASSERT(CanSend());
+  MOZ_ASSERT(aTexture);
+  MOZ_ASSERT(aTexture->IsSharedWithCompositor());
+  MOZ_ASSERT(aCompositable->IsConnected());
+  if (!aTexture || !aTexture->IsSharedWithCompositor() ||
+      !aCompositable->IsConnected()) {
+    return;
+  }
+
+  mTxn->AddNoSwapEdit(CompositableOperation(
+      aCompositable->GetIPCHandle(),
+      OpRemoveTexture(WrapNotNull(aTexture->GetIPDLActor()))));
+}
+
+bool ImageBridgeChild::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+bool ImageBridgeChild::CanPostTask() const {
+  // During shutdown, the cycle collector may free objects that are holding a
+  // reference to ImageBridgeChild. Since this happens on the main thread,
+  // ImageBridgeChild will attempt to post a task to the ImageBridge thread.
+  // However the thread manager has already been shut down, so the task cannot
+  // post.
+  //
+  // It's okay if this races. We only care about the shutdown case where
+  // everything's happening on the main thread. Even if it races outside of
+  // shutdown, it's still harmless to post the task, since the task must
+  // check CanSend().
+  return !mDestroyed;
+}
+
+void ImageBridgeChild::ReleaseCompositable(const CompositableHandle& aHandle) {
+  if (!InImageBridgeChildThread()) {
+    // If we can't post a task, then we definitely cannot send, so there's
+    // no reason to queue up this send.
+    if (!CanPostTask()) {
+      return;
+    }
+
+    RefPtr<Runnable> runnable =
+        WrapRunnable(RefPtr<ImageBridgeChild>(this),
+                     &ImageBridgeChild::ReleaseCompositable, aHandle);
+    GetThread()->Dispatch(runnable.forget());
+    return;
+  }
+
+  if (!CanSend()) {
+    return;
+  }
+
+  if (!DestroyInTransaction(aHandle)) {
+    SendReleaseCompositable(aHandle);
+  }
+
+  {
+    MutexAutoLock lock(mContainerMapLock);
+    mImageContainerListeners.erase(aHandle.Value());
+  }
+}
+
+bool ImageBridgeChild::CanSend() const {
+  MOZ_ASSERT(InImageBridgeChildThread());
+  return mCanSend;
+}
+
+void ImageBridgeChild::HandleFatalError(const char* aMsg) {
+  dom::ContentChild::FatalErrorIfNotUsingGPUProcess(aMsg, OtherPid());
+}
+
+wr::MaybeExternalImageId ImageBridgeChild::GetNextExternalImageId() {
+  static uint32_t sNextID = 1;
+  ++sNextID;
+  MOZ_RELEASE_ASSERT(sNextID != UINT32_MAX);
+
+  uint64_t imageId = mNamespace;
+  imageId = imageId << 32 | sNextID;
+  return Some(wr::ToExternalImageId(imageId));
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/ImageBridgeChild.h b/gfx/layers/ipc/ImageBridgeChild.h
new file mode 100644
index 0000000000..d5a8b7199d
--- /dev/null
+++ b/gfx/layers/ipc/ImageBridgeChild.h
@@ -0,0 +1,380 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_IMAGEBRIDGECHILD_H
+#define MOZILLA_GFX_IMAGEBRIDGECHILD_H
+
+#include <stddef.h>  // for size_t
+#include <stdint.h>  // for uint32_t, uint64_t
+#include <unordered_map>
+
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/Atomics.h"
+#include "mozilla/RefPtr.h"            // for already_AddRefed
+#include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
+#include "mozilla/layers/CompositableForwarder.h"
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/PImageBridgeChild.h"
+#include "mozilla/layers/TextureForwarder.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/webrender/WebRenderTypes.h"
+#include "nsRegion.h"  // for nsIntRegion
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/ReentrantMonitor.h"  // for ReentrantMonitor, etc
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+}  // namespace ipc
+
+namespace layers {
+
+class ImageClient;
+class ImageContainer;
+class ImageContainerListener;
+class ImageBridgeParent;
+class CompositableClient;
+struct CompositableTransaction;
+class Image;
+class TextureClient;
+class SynchronousTask;
+
+/**
+ * Returns true if the current thread is the ImageBrdigeChild's thread.
+ *
+ * Can be called from any thread.
+ */
+bool InImageBridgeChildThread();
+
+/**
+ * The ImageBridge protocol is meant to allow ImageContainers to forward images
+ * directly to the compositor thread/process without using the main thread.
+ *
+ * ImageBridgeChild is a CompositableForwarder just like ShadowLayerForwarder.
+ * This means it also does transactions with the compositor thread/process,
+ * except that the transactions are restricted to operations on the
+ * Compositables and cannot contain messages affecting layers directly.
+ *
+ * ImageBridgeChild is also a ISurfaceAllocator. It can be used to allocate or
+ * deallocate data that is shared with the compositor. The main differerence
+ * with other ISurfaceAllocators is that some of its overriden methods can be
+ * invoked from any thread.
+ *
+ * There are three important phases in the ImageBridge protocol. These three
+ * steps can do different things depending if (A) the ImageContainer uses
+ * ImageBridge or (B) it does not use ImageBridge:
+ *
+ * - When an ImageContainer calls its method SetCurrentImage:
+ *   - (A) The image is sent directly to the compositor process through the
+ *   ImageBridge IPDL protocol.
+ *   On the compositor side the image is stored in a global table that
+ *   associates the image with an ID corresponding to the ImageContainer, and a
+ *   composition is triggered.
+ *   - (B) Since it does not have an ImageBridge, the image is not sent yet.
+ *   instead the will be sent to the compositor during the next layer
+ *   transaction (on the main thread).
+ *
+ * - During a Layer transaction:
+ *   - (A) The ImageContainer uses ImageBridge. The image is already available
+ *   to the compositor process because it has been sent with SetCurrentImage.
+ *   Yet, the CompositableHost on the compositor side will needs the ID
+ *   referring to the ImageContainer to access the Image. So during the Swap
+ *   operation that happens in the transaction, we swap the container ID rather
+ *   than the image data.
+ *   - (B) Since the ImageContainer does not use ImageBridge, the image data is
+ *   swaped.
+ *
+ * - During composition:
+ *   - (A) The CompositableHost has an AsyncID, it looks up the ID in the
+ *   global table to see if there is an image. If there is no image, nothing is
+ *   rendered.
+ *   - (B) The CompositableHost has image data rather than an ID (meaning it is
+ *   not using ImageBridge), then it just composites the image data normally.
+ *
+ * This means that there might be a possibility for the ImageBridge to send the
+ * first frame before the first layer transaction that will pass the container
+ * ID to the CompositableHost happens. In this (unlikely) case the layer is not
+ * composited until the layer transaction happens. This means this scenario is
+ * not harmful.
+ *
+ * Since sending an image through imageBridge triggers compositing, the main
+ * thread is not used at all (except for the very first transaction that
+ * provides the CompositableHost with an AsyncID).
+ */
+class ImageBridgeChild final : public PImageBridgeChild,
+                               public CompositableForwarder,
+                               public TextureForwarder {
+  friend class ImageContainer;
+
+  typedef nsTArray<AsyncParentMessageData> AsyncParentMessageArray;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageBridgeChild, override);
+
+  TextureForwarder* GetTextureForwarder() override { return this; }
+  LayersIPCActor* GetLayersIPCActor() override { return this; }
+
+  /**
+   * Creates the image bridge with a dedicated thread for ImageBridgeChild.
+   *
+   * We may want to use a specifi thread in the future. In this case, use
+   * CreateWithThread instead.
+   */
+  static void InitSameProcess(uint32_t aNamespace);
+
+  static void InitWithGPUProcess(Endpoint<PImageBridgeChild>&& aEndpoint,
+                                 uint32_t aNamespace);
+  static bool InitForContent(Endpoint<PImageBridgeChild>&& aEndpoint,
+                             uint32_t aNamespace);
+  static bool ReinitForContent(Endpoint<PImageBridgeChild>&& aEndpoint,
+                               uint32_t aNamespace);
+
+  /**
+   * Destroys the image bridge by calling DestroyBridge, and destroys the
+   * ImageBridge's thread.
+   *
+   * If you don't want to destroy the thread, call DestroyBridge directly
+   * instead.
+   */
+  static void ShutDown();
+
+  /**
+   * returns the singleton instance.
+   *
+   * can be called from any thread.
+   */
+  static RefPtr<ImageBridgeChild> GetSingleton();
+
+  static void IdentifyCompositorTextureHost(
+      const TextureFactoryIdentifier& aIdentifier);
+
+  void BeginTransaction();
+  void EndTransaction();
+
+  FixedSizeSmallShmemSectionAllocator* GetTileLockAllocator() override;
+
+  /**
+   * Returns the ImageBridgeChild's thread.
+   *
+   * Can be called from any thread.
+   */
+  nsISerialEventTarget* GetThread() const override;
+
+  base::ProcessId GetParentPid() const override { return OtherPid(); }
+
+  void SyncWithCompositor(
+      const Maybe<uint64_t>& aWindowID = Nothing()) override;
+
+  PTextureChild* AllocPTextureChild(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+      const uint64_t& aSerial,
+      const wr::MaybeExternalImageId& aExternalImageId);
+
+  bool DeallocPTextureChild(PTextureChild* actor);
+
+  PMediaSystemResourceManagerChild* AllocPMediaSystemResourceManagerChild();
+  bool DeallocPMediaSystemResourceManagerChild(
+      PMediaSystemResourceManagerChild* aActor);
+
+  mozilla::ipc::IPCResult RecvParentAsyncMessages(
+      nsTArray<AsyncParentMessageData>&& aMessages);
+
+  mozilla::ipc::IPCResult RecvDidComposite(
+      nsTArray<ImageCompositeNotification>&& aNotifications);
+
+  mozilla::ipc::IPCResult RecvReportFramesDropped(
+      const CompositableHandle& aHandle, const uint32_t& aFrames);
+
+  // Create an ImageClient from any thread.
+  RefPtr<ImageClient> CreateImageClient(CompositableType aType,
+                                        ImageContainer* aImageContainer);
+
+  // Create an ImageClient from the ImageBridge thread.
+  RefPtr<ImageClient> CreateImageClientNow(CompositableType aType,
+                                           ImageContainer* aImageContainer);
+
+  void UpdateImageClient(RefPtr<ImageContainer> aContainer);
+
+  void UpdateCompositable(const RefPtr<ImageContainer> aContainer,
+                          const RemoteTextureId aTextureId,
+                          const RemoteTextureOwnerId aOwnerId,
+                          const gfx::IntSize aSize, const TextureFlags aFlags,
+                          const RefPtr<FwdTransactionTracker> aTracker);
+
+  /**
+   * Flush all Images sent to CompositableHost.
+   */
+  void FlushAllImages(ImageClient* aClient, ImageContainer* aContainer);
+
+  bool IPCOpen() const override { return mCanSend; }
+
+ private:
+  /**
+   * This must be called by the static function DeleteImageBridgeSync defined
+   * in ImageBridgeChild.cpp ONLY.
+   */
+  virtual ~ImageBridgeChild();
+
+  // Helpers for dispatching.
+  void CreateImageClientSync(SynchronousTask* aTask,
+                             RefPtr<ImageClient>* result,
+                             CompositableType aType,
+                             ImageContainer* aImageContainer);
+
+  void FlushAllImagesSync(SynchronousTask* aTask, ImageClient* aClient,
+                          ImageContainer* aContainer);
+
+  void ProxyAllocShmemNow(SynchronousTask* aTask, size_t aSize,
+                          mozilla::ipc::Shmem* aShmem, bool aUnsafe,
+                          bool* aSuccess);
+  void ProxyDeallocShmemNow(SynchronousTask* aTask, mozilla::ipc::Shmem* aShmem,
+                            bool* aResult);
+
+  void UpdateTextureFactoryIdentifier(
+      const TextureFactoryIdentifier& aIdentifier);
+
+ public:
+  // CompositableForwarder
+
+  void Connect(CompositableClient* aCompositable,
+               ImageContainer* aImageContainer) override;
+
+  bool UsesImageBridge() const override { return true; }
+
+  /**
+   * See CompositableForwarder::UseTextures
+   */
+  void UseTextures(CompositableClient* aCompositable,
+                   const nsTArray<TimedTextureClient>& aTextures) override;
+
+  void UseRemoteTexture(CompositableClient* aCompositable,
+                        const RemoteTextureId aTextureId,
+                        const RemoteTextureOwnerId aOwnerId,
+                        const gfx::IntSize aSize, const TextureFlags aFlags,
+                        const RefPtr<FwdTransactionTracker>& aTracker) override;
+
+  void ReleaseCompositable(const CompositableHandle& aHandle) override;
+
+  void ForgetImageContainer(const CompositableHandle& aHandle);
+
+  /**
+   * Hold TextureClient ref until end of usage on host side if
+   * TextureFlags::RECYCLE is set. Host side's usage is checked via
+   * CompositableRef.
+   */
+  void HoldUntilCompositableRefReleasedIfNecessary(TextureClient* aClient);
+
+  /**
+   * Notify id of Texture When host side end its use. Transaction id is used to
+   * make sure if there is no newer usage.
+   */
+  void NotifyNotUsed(uint64_t aTextureId, uint64_t aFwdTransactionId);
+
+  void CancelWaitForNotifyNotUsed(uint64_t aTextureId) override;
+
+  bool DestroyInTransaction(PTextureChild* aTexture) override;
+  bool DestroyInTransaction(const CompositableHandle& aHandle);
+
+  void RemoveTextureFromCompositable(CompositableClient* aCompositable,
+                                     TextureClient* aTexture) override;
+
+  // ISurfaceAllocator
+
+  /**
+   * See ISurfaceAllocator.h
+   * Can be used from any thread.
+   * If used outside the ImageBridgeChild thread, it will proxy a synchronous
+   * call on the ImageBridgeChild thread.
+   */
+  bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+
+  /**
+   * See ISurfaceAllocator.h
+   * Can be used from any thread.
+   * If used outside the ImageBridgeChild thread, it will proxy a synchronous
+   * call on the ImageBridgeChild thread.
+   */
+  bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+  PTextureChild* CreateTexture(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+      LayersBackend aLayersBackend, TextureFlags aFlags,
+      const dom::ContentParentId& aContentId, uint64_t aSerial,
+      wr::MaybeExternalImageId& aExternalImageId) override;
+
+  bool IsSameProcess() const override;
+
+  FwdTransactionCounter& GetFwdTransactionCounter() override {
+    return mFwdTransactionCounter;
+  }
+
+  bool InForwarderThread() override { return InImageBridgeChildThread(); }
+
+  void HandleFatalError(const char* aMsg) override;
+
+  wr::MaybeExternalImageId GetNextExternalImageId() override;
+
+ protected:
+  explicit ImageBridgeChild(uint32_t aNamespace);
+  bool DispatchAllocShmemInternal(size_t aSize, Shmem* aShmem, bool aUnsafe);
+
+  void Bind(Endpoint<PImageBridgeChild>&& aEndpoint);
+  void BindSameProcess(RefPtr<ImageBridgeParent> aParent);
+
+  void SendImageBridgeThreadId();
+
+  void WillShutdown();
+  void ShutdownStep1(SynchronousTask* aTask);
+  void ShutdownStep2(SynchronousTask* aTask);
+  void MarkShutDown();
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  bool CanSend() const;
+  bool CanPostTask() const;
+
+  static void ShutdownSingleton();
+
+ private:
+  uint32_t mNamespace;
+
+  CompositableTransaction* mTxn;
+  UniquePtr<FixedSizeSmallShmemSectionAllocator> mSectionAllocator;
+
+  mozilla::Atomic<bool> mCanSend;
+  mozilla::Atomic<bool> mDestroyed;
+
+  /**
+   * Transaction id of CompositableForwarder.
+   * It is incrementaed by UpdateFwdTransactionId() in each BeginTransaction()
+   * call.
+   */
+  FwdTransactionCounter mFwdTransactionCounter;
+
+  /**
+   * Hold TextureClients refs until end of their usages on host side.
+   * It defer calling of TextureClient recycle callback.
+   */
+  std::unordered_map<uint64_t, RefPtr<TextureClient>>
+      mTexturesWaitingNotifyNotUsed;
+
+  /**
+   * Mapping from async compositable IDs to image containers.
+   */
+  Mutex mContainerMapLock MOZ_UNANNOTATED;
+  std::unordered_map<uint64_t, RefPtr<ImageContainerListener>>
+      mImageContainerListeners;
+  RefPtr<ImageContainerListener> FindListener(
+      const CompositableHandle& aHandle);
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/ImageBridgeParent.cpp b/gfx/layers/ipc/ImageBridgeParent.cpp
new file mode 100644
index 0000000000..0f2bbee4f4
--- /dev/null
+++ b/gfx/layers/ipc/ImageBridgeParent.cpp
@@ -0,0 +1,440 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ImageBridgeParent.h"
+#include <stdint.h>            // for uint64_t, uint32_t
+#include "CompositableHost.h"  // for CompositableParent, Create
+#include "base/process.h"      // for ProcessId
+#include "base/task.h"         // for CancelableTask, DeleteTask, etc
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/gfx/Point.h"  // for IntSize
+#include "mozilla/Hal.h"        // for hal::SetCurrentThreadPriority()
+#include "mozilla/HalTypes.h"   // for hal::THREAD_PRIORITY_COMPOSITOR
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/ipc/MessageChannel.h"  // for MessageChannel, etc
+#include "mozilla/media/MediaSystemResourceManagerParent.h"  // for MediaSystemResourceManagerParent
+#include "mozilla/layers/BufferTexture.h"
+#include "mozilla/layers/CompositableTransactionParent.h"
+#include "mozilla/layers/LayersMessages.h"  // for EditReply
+#include "mozilla/layers/PImageBridgeParent.h"
+#include "mozilla/layers/TextureHostOGL.h"  // for TextureHostOGL
+#include "mozilla/layers/Compositor.h"
+#include "mozilla/layers/RemoteTextureMap.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/mozalloc.h"  // for operator new, etc
+#include "mozilla/ProfilerLabels.h"
+#include "mozilla/ProfilerMarkers.h"
+#include "mozilla/Unused.h"
+#include "nsDebug.h"                 // for NS_ASSERTION, etc
+#include "nsISupportsImpl.h"         // for ImageBridgeParent::Release, etc
+#include "nsTArray.h"                // for nsTArray, nsTArray_Impl
+#include "nsTArrayForwardDeclare.h"  // for nsTArray
+#include "nsXULAppAPI.h"             // for XRE_GetIOMessageLoop
+#include "mozilla/layers/TextureHost.h"
+#include "nsThreadUtils.h"
+
+#if defined(XP_WIN)
+#  include "mozilla/layers/TextureD3D11.h"
+#endif
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::ipc;
+using namespace mozilla::gfx;
+using namespace mozilla::media;
+
+ImageBridgeParent::ImageBridgeMap ImageBridgeParent::sImageBridges;
+
+StaticAutoPtr<mozilla::Monitor> sImageBridgesLock;
+
+static StaticRefPtr<ImageBridgeParent> sImageBridgeParentSingleton;
+
+/* static */
+void ImageBridgeParent::Setup() {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!sImageBridgesLock) {
+    sImageBridgesLock = new Monitor("ImageBridges");
+    mozilla::ClearOnShutdown(&sImageBridgesLock);
+  }
+}
+
+ImageBridgeParent::ImageBridgeParent(nsISerialEventTarget* aThread,
+                                     ProcessId aChildProcessId,
+                                     dom::ContentParentId aContentId)
+    : mThread(aThread),
+      mContentId(aContentId),
+      mClosed(false),
+      mCompositorThreadHolder(CompositorThreadHolder::GetSingleton()) {
+  MOZ_ASSERT(NS_IsMainThread());
+  SetOtherProcessId(aChildProcessId);
+  mRemoteTextureTxnScheduler = RemoteTextureTxnScheduler::Create(this);
+}
+
+ImageBridgeParent::~ImageBridgeParent() = default;
+
+/* static */
+ImageBridgeParent* ImageBridgeParent::CreateSameProcess() {
+  base::ProcessId pid = base::GetCurrentProcId();
+  RefPtr<ImageBridgeParent> parent =
+      new ImageBridgeParent(CompositorThread(), pid, dom::ContentParentId());
+
+  {
+    MonitorAutoLock lock(*sImageBridgesLock);
+    MOZ_RELEASE_ASSERT(sImageBridges.count(pid) == 0);
+    sImageBridges[pid] = parent;
+  }
+
+  sImageBridgeParentSingleton = parent;
+  return parent;
+}
+
+/* static */
+bool ImageBridgeParent::CreateForGPUProcess(
+    Endpoint<PImageBridgeParent>&& aEndpoint) {
+  MOZ_ASSERT(XRE_GetProcessType() == GeckoProcessType_GPU);
+
+  nsCOMPtr<nsISerialEventTarget> compositorThread = CompositorThread();
+  if (!compositorThread) {
+    return false;
+  }
+
+  RefPtr<ImageBridgeParent> parent = new ImageBridgeParent(
+      compositorThread, aEndpoint.OtherPid(), dom::ContentParentId());
+
+  compositorThread->Dispatch(NewRunnableMethod<Endpoint<PImageBridgeParent>&&>(
+      "layers::ImageBridgeParent::Bind", parent, &ImageBridgeParent::Bind,
+      std::move(aEndpoint)));
+
+  sImageBridgeParentSingleton = parent;
+  return true;
+}
+
+/* static */
+void ImageBridgeParent::ShutdownInternal() {
+  // We make a copy because we don't want to hold the lock while closing and we
+  // don't want the object to get freed underneath us.
+  nsTArray<RefPtr<ImageBridgeParent>> actors;
+  {
+    MonitorAutoLock lock(*sImageBridgesLock);
+    for (const auto& iter : sImageBridges) {
+      actors.AppendElement(iter.second);
+    }
+  }
+
+  for (auto const& actor : actors) {
+    MOZ_RELEASE_ASSERT(!actor->mClosed);
+    actor->Close();
+  }
+
+  sImageBridgeParentSingleton = nullptr;
+}
+
+/* static */
+void ImageBridgeParent::Shutdown() {
+  CompositorThread()->Dispatch(NS_NewRunnableFunction(
+      "ImageBridgeParent::Shutdown",
+      []() -> void { ImageBridgeParent::ShutdownInternal(); }));
+}
+
+void ImageBridgeParent::ActorDestroy(ActorDestroyReason aWhy) {
+  // Can't alloc/dealloc shmems from now on.
+  mClosed = true;
+
+  if (mRemoteTextureTxnScheduler) {
+    mRemoteTextureTxnScheduler = nullptr;
+  }
+  for (const auto& entry : mCompositables) {
+    entry.second->OnReleased();
+  }
+  mCompositables.clear();
+  {
+    MonitorAutoLock lock(*sImageBridgesLock);
+    sImageBridges.erase(OtherPid());
+  }
+  GetThread()->Dispatch(
+      NewRunnableMethod("layers::ImageBridgeParent::DeferredDestroy", this,
+                        &ImageBridgeParent::DeferredDestroy));
+
+  // It is very important that this method gets called at shutdown (be it a
+  // clean or an abnormal shutdown), because DeferredDestroy is what clears
+  // mCompositorThreadHolder. If mCompositorThreadHolder is not null and
+  // ActorDestroy is not called, the ImageBridgeParent is leaked which causes
+  // the CompositorThreadHolder to be leaked and CompsoitorParent's shutdown
+  // ends up spinning the event loop forever, waiting for the compositor thread
+  // to terminate.
+}
+
+class MOZ_STACK_CLASS AutoImageBridgeParentAsyncMessageSender final {
+ public:
+  explicit AutoImageBridgeParentAsyncMessageSender(
+      ImageBridgeParent* aImageBridge,
+      nsTArray<OpDestroy>* aToDestroy = nullptr)
+      : mImageBridge(aImageBridge), mToDestroy(aToDestroy) {
+    mImageBridge->SetAboutToSendAsyncMessages();
+  }
+
+  ~AutoImageBridgeParentAsyncMessageSender() {
+    mImageBridge->SendPendingAsyncMessages();
+    if (mToDestroy) {
+      for (const auto& op : *mToDestroy) {
+        mImageBridge->DestroyActor(op);
+      }
+    }
+  }
+
+ private:
+  ImageBridgeParent* mImageBridge;
+  nsTArray<OpDestroy>* mToDestroy;
+};
+
+mozilla::ipc::IPCResult ImageBridgeParent::RecvUpdate(
+    EditArray&& aEdits, OpDestroyArray&& aToDestroy,
+    const uint64_t& aFwdTransactionId) {
+  AUTO_PROFILER_TRACING_MARKER("Paint", "ImageBridgeTransaction", GRAPHICS);
+  AUTO_PROFILER_LABEL("ImageBridgeParent::RecvUpdate", GRAPHICS);
+
+  // This ensures that destroy operations are always processed. It is not safe
+  // to early-return from RecvUpdate without doing so.
+  AutoImageBridgeParentAsyncMessageSender autoAsyncMessageSender(this,
+                                                                 &aToDestroy);
+  UpdateFwdTransactionId(aFwdTransactionId);
+
+  auto result = IPC_OK();
+
+  for (const auto& edit : aEdits) {
+    RefPtr<CompositableHost> compositable =
+        FindCompositable(edit.compositable());
+    if (!compositable ||
+        !ReceiveCompositableUpdate(edit.detail(), WrapNotNull(compositable),
+                                   edit.compositable())) {
+      result = IPC_FAIL_NO_REASON(this);
+      break;
+    }
+    uint32_t dropped = compositable->GetDroppedFrames();
+    if (dropped) {
+      Unused << SendReportFramesDropped(edit.compositable(), dropped);
+    }
+  }
+
+  if (mRemoteTextureTxnScheduler) {
+    mRemoteTextureTxnScheduler->NotifyTxn(aFwdTransactionId);
+  }
+
+  return result;
+}
+
+/* static */
+bool ImageBridgeParent::CreateForContent(
+    Endpoint<PImageBridgeParent>&& aEndpoint, dom::ContentParentId aContentId) {
+  nsCOMPtr<nsISerialEventTarget> compositorThread = CompositorThread();
+  if (!compositorThread) {
+    return false;
+  }
+
+  RefPtr<ImageBridgeParent> bridge =
+      new ImageBridgeParent(compositorThread, aEndpoint.OtherPid(), aContentId);
+  compositorThread->Dispatch(NewRunnableMethod<Endpoint<PImageBridgeParent>&&>(
+      "layers::ImageBridgeParent::Bind", bridge, &ImageBridgeParent::Bind,
+      std::move(aEndpoint)));
+
+  return true;
+}
+
+void ImageBridgeParent::Bind(Endpoint<PImageBridgeParent>&& aEndpoint) {
+  if (!aEndpoint.Bind(this)) return;
+
+  // If the child process ID was reused by the OS before the ImageBridgeParent
+  // object was destroyed, we need to clean it up first.
+  RefPtr<ImageBridgeParent> oldActor;
+  {
+    MonitorAutoLock lock(*sImageBridgesLock);
+    ImageBridgeMap::const_iterator i = sImageBridges.find(OtherPid());
+    if (i != sImageBridges.end()) {
+      oldActor = i->second;
+    }
+  }
+
+  // We can't hold the lock during Close because it erases itself from the map.
+  if (oldActor) {
+    MOZ_RELEASE_ASSERT(!oldActor->mClosed);
+    oldActor->Close();
+  }
+
+  {
+    MonitorAutoLock lock(*sImageBridgesLock);
+    sImageBridges[OtherPid()] = this;
+  }
+}
+
+mozilla::ipc::IPCResult ImageBridgeParent::RecvWillClose() {
+  // If there is any texture still alive we have to force it to deallocate the
+  // device data (GL textures, etc.) now because shortly after SenStop() returns
+  // on the child side the widget will be destroyed along with it's associated
+  // GL context.
+  nsTArray<PTextureParent*> textures;
+  ManagedPTextureParent(textures);
+  for (unsigned int i = 0; i < textures.Length(); ++i) {
+    RefPtr<TextureHost> tex = TextureHost::AsTextureHost(textures[i]);
+    tex->DeallocateDeviceData();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ImageBridgeParent::RecvNewCompositable(
+    const CompositableHandle& aHandle, const TextureInfo& aInfo) {
+  RefPtr<CompositableHost> host = AddCompositable(aHandle, aInfo);
+  if (!host) {
+    return IPC_FAIL_NO_REASON(this);
+  }
+
+  host->SetAsyncRef(AsyncCompositableRef(OtherPid(), aHandle));
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ImageBridgeParent::RecvReleaseCompositable(
+    const CompositableHandle& aHandle) {
+  ReleaseCompositable(aHandle);
+  return IPC_OK();
+}
+
+PTextureParent* ImageBridgeParent::AllocPTextureParent(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+    const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+    const uint64_t& aSerial, const wr::MaybeExternalImageId& aExternalImageId) {
+  return TextureHost::CreateIPDLActor(this, aSharedData, std::move(aReadLock),
+                                      aLayersBackend, aFlags, mContentId,
+                                      aSerial, aExternalImageId);
+}
+
+bool ImageBridgeParent::DeallocPTextureParent(PTextureParent* actor) {
+  return TextureHost::DestroyIPDLActor(actor);
+}
+
+PMediaSystemResourceManagerParent*
+ImageBridgeParent::AllocPMediaSystemResourceManagerParent() {
+  return new mozilla::media::MediaSystemResourceManagerParent();
+}
+
+bool ImageBridgeParent::DeallocPMediaSystemResourceManagerParent(
+    PMediaSystemResourceManagerParent* aActor) {
+  MOZ_ASSERT(aActor);
+  delete static_cast<mozilla::media::MediaSystemResourceManagerParent*>(aActor);
+  return true;
+}
+
+void ImageBridgeParent::SendAsyncMessage(
+    const nsTArray<AsyncParentMessageData>& aMessage) {
+  mozilla::Unused << SendParentAsyncMessages(aMessage);
+}
+
+class ProcessIdComparator {
+ public:
+  bool Equals(const ImageCompositeNotificationInfo& aA,
+              const ImageCompositeNotificationInfo& aB) const {
+    return aA.mImageBridgeProcessId == aB.mImageBridgeProcessId;
+  }
+  bool LessThan(const ImageCompositeNotificationInfo& aA,
+                const ImageCompositeNotificationInfo& aB) const {
+    return aA.mImageBridgeProcessId < aB.mImageBridgeProcessId;
+  }
+};
+
+/* static */
+bool ImageBridgeParent::NotifyImageComposites(
+    nsTArray<ImageCompositeNotificationInfo>& aNotifications) {
+  // Group the notifications by destination process ID and then send the
+  // notifications in one message per group.
+  aNotifications.Sort(ProcessIdComparator());
+  uint32_t i = 0;
+  bool ok = true;
+  while (i < aNotifications.Length()) {
+    AutoTArray<ImageCompositeNotification, 1> notifications;
+    notifications.AppendElement(aNotifications[i].mNotification);
+    uint32_t end = i + 1;
+    MOZ_ASSERT(aNotifications[i].mNotification.compositable());
+    ProcessId pid = aNotifications[i].mImageBridgeProcessId;
+    while (end < aNotifications.Length() &&
+           aNotifications[end].mImageBridgeProcessId == pid) {
+      notifications.AppendElement(aNotifications[end].mNotification);
+      ++end;
+    }
+    RefPtr<ImageBridgeParent> bridge = GetInstance(pid);
+    if (!bridge || bridge->mClosed) {
+      i = end;
+      continue;
+    }
+    bridge->SendPendingAsyncMessages();
+    if (!bridge->SendDidComposite(notifications)) {
+      ok = false;
+    }
+    i = end;
+  }
+  return ok;
+}
+
+void ImageBridgeParent::DeferredDestroy() { mCompositorThreadHolder = nullptr; }
+
+already_AddRefed<ImageBridgeParent> ImageBridgeParent::GetInstance(
+    ProcessId aId) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MonitorAutoLock lock(*sImageBridgesLock);
+  ImageBridgeMap::const_iterator i = sImageBridges.find(aId);
+  if (i == sImageBridges.end()) {
+    NS_WARNING("Cannot find image bridge for process!");
+    return nullptr;
+  }
+  RefPtr<ImageBridgeParent> bridge = i->second;
+  return bridge.forget();
+}
+
+bool ImageBridgeParent::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  if (mClosed) {
+    return false;
+  }
+  return PImageBridgeParent::AllocShmem(aSize, aShmem);
+}
+
+bool ImageBridgeParent::AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) {
+  if (mClosed) {
+    return false;
+  }
+  return PImageBridgeParent::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool ImageBridgeParent::DeallocShmem(ipc::Shmem& aShmem) {
+  if (mClosed) {
+    return false;
+  }
+  return PImageBridgeParent::DeallocShmem(aShmem);
+}
+
+bool ImageBridgeParent::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void ImageBridgeParent::NotifyNotUsed(PTextureParent* aTexture,
+                                      uint64_t aTransactionId) {
+  RefPtr<TextureHost> texture = TextureHost::AsTextureHost(aTexture);
+  if (!texture) {
+    return;
+  }
+
+  if (!(texture->GetFlags() & TextureFlags::RECYCLE) &&
+      !(texture->GetFlags() & TextureFlags::WAIT_HOST_USAGE_END)) {
+    return;
+  }
+
+  uint64_t textureId = TextureHost::GetTextureSerial(aTexture);
+  mPendingAsyncMessage.push_back(OpNotifyNotUsed(textureId, aTransactionId));
+
+  if (!IsAboutToSendAsyncMessages()) {
+    SendPendingAsyncMessages();
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/ImageBridgeParent.h b/gfx/layers/ipc/ImageBridgeParent.h
new file mode 100644
index 0000000000..0267be3eaa
--- /dev/null
+++ b/gfx/layers/ipc/ImageBridgeParent.h
@@ -0,0 +1,154 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef gfx_layers_ipc_ImageBridgeParent_h_
+#define gfx_layers_ipc_ImageBridgeParent_h_
+
+#include <stddef.h>  // for size_t
+#include <stdint.h>  // for uint32_t, uint64_t
+#include "CompositableTransactionParent.h"
+#include "mozilla/Assertions.h"  // for MOZ_ASSERT_HELPER2
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/PImageBridgeParent.h"
+#include "nsISupportsImpl.h"
+#include "nsTArrayForwardDeclare.h"  // for nsTArray
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+}  // namespace ipc
+
+namespace layers {
+
+struct ImageCompositeNotificationInfo;
+class RemoteTextureTxnScheduler;
+
+/**
+ * ImageBridgeParent is the manager Protocol of async Compositables.
+ */
+class ImageBridgeParent final : public PImageBridgeParent,
+                                public CompositableParentManager,
+                                public mozilla::ipc::IShmemAllocator {
+ public:
+  typedef nsTArray<CompositableOperation> EditArray;
+  typedef nsTArray<OpDestroy> OpDestroyArray;
+
+ protected:
+  ImageBridgeParent(nsISerialEventTarget* aThread, ProcessId aChildProcessId,
+                    dom::ContentParentId aContentId);
+
+ public:
+  NS_IMETHOD_(MozExternalRefCountType) AddRef() override {
+    return ISurfaceAllocator::AddRef();
+  }
+  NS_IMETHOD_(MozExternalRefCountType) Release() override {
+    return ISurfaceAllocator::Release();
+  }
+
+  /**
+   * Creates the globals of ImageBridgeParent.
+   */
+  static void Setup();
+
+  static ImageBridgeParent* CreateSameProcess();
+  static bool CreateForGPUProcess(Endpoint<PImageBridgeParent>&& aEndpoint);
+  static bool CreateForContent(Endpoint<PImageBridgeParent>&& aEndpoint,
+                               dom::ContentParentId aContentId);
+  static void Shutdown();
+
+  IShmemAllocator* AsShmemAllocator() override { return this; }
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // CompositableParentManager
+  void SendAsyncMessage(
+      const nsTArray<AsyncParentMessageData>& aMessage) override;
+
+  void NotifyNotUsed(PTextureParent* aTexture,
+                     uint64_t aTransactionId) override;
+
+  base::ProcessId GetChildProcessId() override { return OtherPid(); }
+  dom::ContentParentId GetContentId() override { return mContentId; }
+
+  // PImageBridge
+  mozilla::ipc::IPCResult RecvUpdate(EditArray&& aEdits,
+                                     OpDestroyArray&& aToDestroy,
+                                     const uint64_t& aFwdTransactionId);
+
+  PTextureParent* AllocPTextureParent(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+      const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+      const uint64_t& aSerial,
+      const wr::MaybeExternalImageId& aExternalImageId);
+  bool DeallocPTextureParent(PTextureParent* actor);
+
+  mozilla::ipc::IPCResult RecvNewCompositable(const CompositableHandle& aHandle,
+                                              const TextureInfo& aInfo);
+  mozilla::ipc::IPCResult RecvReleaseCompositable(
+      const CompositableHandle& aHandle);
+
+  PMediaSystemResourceManagerParent* AllocPMediaSystemResourceManagerParent();
+  bool DeallocPMediaSystemResourceManagerParent(
+      PMediaSystemResourceManagerParent* aActor);
+
+  // Shutdown step 1
+  mozilla::ipc::IPCResult RecvWillClose();
+
+  nsISerialEventTarget* GetThread() const { return mThread; }
+
+  // IShmemAllocator
+
+  bool AllocShmem(size_t aSize, ipc::Shmem* aShmem) override;
+
+  bool AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) override;
+
+  bool DeallocShmem(ipc::Shmem& aShmem) override;
+
+  bool IsSameProcess() const override;
+
+  static already_AddRefed<ImageBridgeParent> GetInstance(ProcessId aId);
+
+  static bool NotifyImageComposites(
+      nsTArray<ImageCompositeNotificationInfo>& aNotifications);
+
+  bool UsesImageBridge() const override { return true; }
+
+  bool IPCOpen() const override { return !mClosed; }
+
+ protected:
+  void Bind(Endpoint<PImageBridgeParent>&& aEndpoint);
+
+ private:
+  virtual ~ImageBridgeParent();
+
+  static void ShutdownInternal();
+
+  void DeferredDestroy();
+  nsCOMPtr<nsISerialEventTarget> mThread;
+
+  dom::ContentParentId mContentId;
+
+  bool mClosed;
+
+  /**
+   * Map of all living ImageBridgeParent instances
+   */
+  typedef std::map<base::ProcessId, ImageBridgeParent*> ImageBridgeMap;
+  static ImageBridgeMap sImageBridges;
+
+  RefPtr<CompositorThreadHolder> mCompositorThreadHolder;
+
+  RefPtr<RemoteTextureTxnScheduler> mRemoteTextureTxnScheduler;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // gfx_layers_ipc_ImageBridgeParent_h_
diff --git a/gfx/layers/ipc/KnowsCompositor.cpp b/gfx/layers/ipc/KnowsCompositor.cpp
new file mode 100644
index 0000000000..8099c4de88
--- /dev/null
+++ b/gfx/layers/ipc/KnowsCompositor.cpp
@@ -0,0 +1,108 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "KnowsCompositor.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/ImageBridgeChild.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+
+namespace mozilla::layers {
+
+void KnowsCompositor::IdentifyTextureHost(
+    const TextureFactoryIdentifier& aIdentifier) {
+  auto lock = mData.Lock();
+  lock.ref().mTextureFactoryIdentifier = aIdentifier;
+
+  lock.ref().mSyncObject =
+      SyncObjectClient::CreateSyncObjectClientForContentDevice(
+          aIdentifier.mSyncHandle);
+}
+
+KnowsCompositor::KnowsCompositor()
+    : mData("KnowsCompositorMutex"), mSerial(++sSerialCounter) {}
+
+KnowsCompositor::~KnowsCompositor() = default;
+
+KnowsCompositorMediaProxy::KnowsCompositorMediaProxy(
+    const TextureFactoryIdentifier& aIdentifier) {
+  auto lock = mData.Lock();
+  lock.ref().mTextureFactoryIdentifier = aIdentifier;
+  // overwrite mSerial's value set by the parent class because we use the same
+  // serial as the KnowsCompositor we are proxying.
+  mThreadSafeAllocator = ImageBridgeChild::GetSingleton();
+  lock.ref().mSyncObject = mThreadSafeAllocator->GetSyncObject();
+}
+
+KnowsCompositorMediaProxy::~KnowsCompositorMediaProxy() = default;
+
+TextureForwarder* KnowsCompositorMediaProxy::GetTextureForwarder() {
+  return mThreadSafeAllocator->GetTextureForwarder();
+}
+
+LayersIPCActor* KnowsCompositorMediaProxy::GetLayersIPCActor() {
+  return mThreadSafeAllocator->GetLayersIPCActor();
+}
+
+void KnowsCompositorMediaProxy::SyncWithCompositor(
+    const Maybe<uint64_t>& aWindowID) {
+  mThreadSafeAllocator->SyncWithCompositor(aWindowID);
+}
+
+bool IsSurfaceDescriptorValid(const SurfaceDescriptor& aSurface) {
+  return aSurface.type() != SurfaceDescriptor::T__None &&
+         aSurface.type() != SurfaceDescriptor::Tnull_t;
+}
+
+uint8_t* GetAddressFromDescriptor(const SurfaceDescriptor& aDescriptor) {
+  MOZ_ASSERT(IsSurfaceDescriptorValid(aDescriptor));
+  MOZ_RELEASE_ASSERT(
+      aDescriptor.type() == SurfaceDescriptor::TSurfaceDescriptorBuffer,
+      "GFX: surface descriptor is not the right type.");
+
+  auto memOrShmem = aDescriptor.get_SurfaceDescriptorBuffer().data();
+  if (memOrShmem.type() == MemoryOrShmem::TShmem) {
+    return memOrShmem.get_Shmem().get<uint8_t>();
+  } else {
+    return reinterpret_cast<uint8_t*>(memOrShmem.get_uintptr_t());
+  }
+}
+
+already_AddRefed<gfx::DataSourceSurface> GetSurfaceForDescriptor(
+    const SurfaceDescriptor& aDescriptor) {
+  if (aDescriptor.type() != SurfaceDescriptor::TSurfaceDescriptorBuffer) {
+    return nullptr;
+  }
+  uint8_t* data = GetAddressFromDescriptor(aDescriptor);
+  auto rgb =
+      aDescriptor.get_SurfaceDescriptorBuffer().desc().get_RGBDescriptor();
+  uint32_t stride = ImageDataSerializer::GetRGBStride(rgb);
+  return gfx::Factory::CreateWrappingDataSourceSurface(data, stride, rgb.size(),
+                                                       rgb.format());
+}
+
+void DestroySurfaceDescriptor(ipc::IShmemAllocator* aAllocator,
+                              SurfaceDescriptor* aSurface) {
+  MOZ_ASSERT(aSurface);
+
+  SurfaceDescriptorBuffer& desc = aSurface->get_SurfaceDescriptorBuffer();
+  switch (desc.data().type()) {
+    case MemoryOrShmem::TShmem: {
+      aAllocator->DeallocShmem(desc.data().get_Shmem());
+      break;
+    }
+    case MemoryOrShmem::Tuintptr_t: {
+      uint8_t* ptr = (uint8_t*)desc.data().get_uintptr_t();
+      GfxMemoryImageReporter::WillFree(ptr);
+      delete[] ptr;
+      break;
+    }
+    default:
+      MOZ_CRASH("surface type not implemented!");
+  }
+  *aSurface = SurfaceDescriptor();
+}
+
+}  // namespace mozilla::layers
diff --git a/gfx/layers/ipc/KnowsCompositor.h b/gfx/layers/ipc/KnowsCompositor.h
new file mode 100644
index 0000000000..2f79a3c171
--- /dev/null
+++ b/gfx/layers/ipc/KnowsCompositor.h
@@ -0,0 +1,233 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_KNOWSCOMPOSITOR
+#define MOZILLA_LAYERS_KNOWSCOMPOSITOR
+
+#include "mozilla/layers/LayersTypes.h"  // for LayersBackend
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/DataMutex.h"
+#include "mozilla/layers/SyncObject.h"
+
+namespace mozilla::layers {
+
+class TextureForwarder;
+class LayersIPCActor;
+class ImageBridgeChild;
+
+/**
+ * An abstract interface for classes that are tied to a specific Compositor
+ * across IPDL and uses TextureFactoryIdentifier to describe this Compositor.
+ */
+class KnowsCompositor {
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  KnowsCompositor();
+  virtual ~KnowsCompositor();
+
+  void IdentifyTextureHost(const TextureFactoryIdentifier& aIdentifier);
+
+  // The sync object for the global content device.
+  RefPtr<SyncObjectClient> GetSyncObject() {
+    auto lock = mData.Lock();
+    if (lock.ref().mSyncObject) {
+      lock.ref().mSyncObject->EnsureInitialized();
+    }
+    return lock.ref().mSyncObject;
+  }
+
+  /// And by "thread-safe" here we merely mean "okay to hold strong references
+  /// to from multiple threads". Not all methods actually are thread-safe.
+  virtual bool IsThreadSafe() const { return true; }
+
+  virtual RefPtr<KnowsCompositor> GetForMedia() {
+    return RefPtr<KnowsCompositor>(this);
+  }
+
+  int32_t GetMaxTextureSize() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mMaxTextureSize;
+  }
+
+  /**
+   * Returns the type of backend that is used off the main thread.
+   * We only don't allow changing the backend type at runtime so this value can
+   * be queried once and will not change until Gecko is restarted.
+   */
+  LayersBackend GetCompositorBackendType() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mParentBackend;
+  }
+
+  WebRenderCompositor GetWebRenderCompositorType() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mWebRenderCompositor;
+  }
+
+  bool SupportsTextureBlitting() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mSupportsTextureBlitting;
+  }
+
+  bool SupportsPartialUploads() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mSupportsPartialUploads;
+  }
+
+  bool SupportsComponentAlpha() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mSupportsComponentAlpha;
+  }
+
+  bool SupportsD3D11NV12() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mSupportsD3D11NV12;
+  }
+
+  bool SupportsD3D11() const {
+    auto lock = mData.Lock();
+    return SupportsD3D11(lock.ref().mTextureFactoryIdentifier);
+  }
+
+  static bool SupportsD3D11(
+      const TextureFactoryIdentifier aTextureFactoryIdentifier) {
+    return aTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR &&
+           (aTextureFactoryIdentifier.mCompositorUseANGLE ||
+            aTextureFactoryIdentifier.mWebRenderCompositor ==
+                layers::WebRenderCompositor::D3D11);
+  }
+
+  bool GetCompositorUseANGLE() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mCompositorUseANGLE;
+  }
+
+  bool GetCompositorUseDComp() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mCompositorUseDComp;
+  }
+
+  bool GetUseCompositorWnd() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mUseCompositorWnd;
+  }
+
+  WebRenderBackend GetWebRenderBackend() const {
+    auto lock = mData.Lock();
+    MOZ_ASSERT(lock.ref().mTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR);
+    return lock.ref().mTextureFactoryIdentifier.mWebRenderBackend;
+  }
+
+  bool UsingHardwareWebRender() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderBackend ==
+               WebRenderBackend::HARDWARE;
+  }
+
+  bool UsingSoftwareWebRender() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderBackend ==
+               WebRenderBackend::SOFTWARE;
+  }
+
+  bool UsingSoftwareWebRenderD3D11() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderBackend ==
+               WebRenderBackend::SOFTWARE &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderCompositor ==
+               layers::WebRenderCompositor::D3D11;
+  }
+
+  bool UsingSoftwareWebRenderOpenGL() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier.mParentBackend ==
+               layers::LayersBackend::LAYERS_WR &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderBackend ==
+               WebRenderBackend::SOFTWARE &&
+           lock.ref().mTextureFactoryIdentifier.mWebRenderCompositor ==
+               layers::WebRenderCompositor::OPENGL;
+  }
+
+  TextureFactoryIdentifier GetTextureFactoryIdentifier() const {
+    auto lock = mData.Lock();
+    return lock.ref().mTextureFactoryIdentifier;
+  }
+
+  int32_t GetSerial() const { return mSerial; }
+
+  /**
+   * Sends a synchronous ping to the compsoitor.
+   *
+   * This is bad for performance and should only be called as a last resort if
+   * the compositor may be blocked for a long period of time, to avoid that the
+   * content process accumulates resource allocations that the compositor is not
+   * consuming and releasing.
+   */
+  virtual void SyncWithCompositor(
+      const Maybe<uint64_t>& aWindowID = Nothing()) {
+    MOZ_ASSERT_UNREACHABLE("Unimplemented");
+  }
+
+  /**
+   * Helpers for finding other related interface. These are infallible.
+   */
+  virtual TextureForwarder* GetTextureForwarder() = 0;
+  virtual LayersIPCActor* GetLayersIPCActor() = 0;
+
+ protected:
+  struct SharedData {
+    TextureFactoryIdentifier mTextureFactoryIdentifier;
+    RefPtr<SyncObjectClient> mSyncObject;
+  };
+  mutable DataMutex<SharedData> mData;
+
+  const int32_t mSerial;
+  static mozilla::Atomic<int32_t> sSerialCounter;
+};
+
+/// Some implementations of KnowsCompositor can be used off their IPDL thread
+/// like the ImageBridgeChild, and others just can't. Instead of passing them
+/// we create a proxy KnowsCompositor that has information about compositor
+/// backend but proxies allocations to the ImageBridge.
+/// This is kind of specific to the needs of media which wants to allocate
+/// textures, usually through the Image Bridge accessed by KnowsCompositor but
+/// also wants access to the compositor backend information that ImageBridge
+/// doesn't know about.
+///
+/// This is really a band aid to what turned into a class hierarchy horror show.
+/// Hopefully we can come back and simplify this some way.
+class KnowsCompositorMediaProxy : public KnowsCompositor {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(KnowsCompositorMediaProxy, override);
+
+  explicit KnowsCompositorMediaProxy(
+      const TextureFactoryIdentifier& aIdentifier);
+
+  TextureForwarder* GetTextureForwarder() override;
+
+  LayersIPCActor* GetLayersIPCActor() override;
+
+  void SyncWithCompositor(
+      const Maybe<uint64_t>& aWindowID = Nothing()) override;
+
+ protected:
+  virtual ~KnowsCompositorMediaProxy();
+
+  RefPtr<ImageBridgeChild> mThreadSafeAllocator;
+};
+
+}  // namespace mozilla::layers
+
+#endif
diff --git a/gfx/layers/ipc/LayerTreeOwnerTracker.cpp b/gfx/layers/ipc/LayerTreeOwnerTracker.cpp
new file mode 100644
index 0000000000..ab3551ad29
--- /dev/null
+++ b/gfx/layers/ipc/LayerTreeOwnerTracker.cpp
@@ -0,0 +1,68 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "LayerTreeOwnerTracker.h"
+
+#include "mozilla/StaticPtr.h"              // for StaticAutoPtr
+#include "mozilla/gfx/GPUChild.h"           // for GPUChild
+#include "mozilla/gfx/GPUProcessManager.h"  // for GPUProcessManager
+
+#include <functional>
+#include <utility>  // for std::make_pair
+
+namespace mozilla {
+namespace layers {
+
+static StaticAutoPtr<LayerTreeOwnerTracker> sSingleton;
+
+LayerTreeOwnerTracker::LayerTreeOwnerTracker()
+    : mLayerIdsLock("LayerTreeOwnerTrackerLock") {}
+
+void LayerTreeOwnerTracker::Initialize() {
+  MOZ_ASSERT(!sSingleton);
+  sSingleton = new LayerTreeOwnerTracker();
+}
+
+void LayerTreeOwnerTracker::Shutdown() { sSingleton = nullptr; }
+
+LayerTreeOwnerTracker* LayerTreeOwnerTracker::Get() { return sSingleton; }
+
+void LayerTreeOwnerTracker::Map(LayersId aLayersId,
+                                base::ProcessId aProcessId) {
+  MutexAutoLock lock(mLayerIdsLock);
+
+  // Add the mapping to the list
+  mLayerIds[aLayersId] = aProcessId;
+}
+
+void LayerTreeOwnerTracker::Unmap(LayersId aLayersId,
+                                  base::ProcessId aProcessId) {
+  MutexAutoLock lock(mLayerIdsLock);
+
+  MOZ_ASSERT(mLayerIds[aLayersId] == aProcessId);
+  mLayerIds.erase(aLayersId);
+}
+
+bool LayerTreeOwnerTracker::IsMapped(LayersId aLayersId,
+                                     base::ProcessId aProcessId) {
+  MutexAutoLock lock(mLayerIdsLock);
+
+  auto iter = mLayerIds.find(aLayersId);
+  return iter != mLayerIds.end() && iter->second == aProcessId;
+}
+
+void LayerTreeOwnerTracker::Iterate(
+    const std::function<void(LayersId aLayersId, base::ProcessId aProcessId)>&
+        aCallback) {
+  MutexAutoLock lock(mLayerIdsLock);
+
+  for (const auto& iter : mLayerIds) {
+    aCallback(iter.first, iter.second);
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/LayerTreeOwnerTracker.h b/gfx/layers/ipc/LayerTreeOwnerTracker.h
new file mode 100644
index 0000000000..651c695309
--- /dev/null
+++ b/gfx/layers/ipc/LayerTreeOwnerTracker.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_LayerTreeOwnerTracker_h
+#define mozilla_layers_LayerTreeOwnerTracker_h
+
+#include "base/process.h"   // for base::ProcessId
+#include "LayersTypes.h"    // for LayersId
+#include "mozilla/Mutex.h"  // for mozilla::Mutex
+
+#include <functional>
+#include <map>
+
+namespace mozilla {
+
+namespace dom {
+class ContentParent;
+}
+
+namespace layers {
+
+/**
+ * A utility class for tracking which content processes should be allowed
+ * to access which layer trees.
+ *
+ * ProcessId's are used to track which content process can access the layer
+ * tree, and in the case of nested browser's we use the top level content
+ * processes' ProcessId.
+ *
+ * This class is only available in the main process and gpu process. Mappings
+ * are synced from main process to the gpu process. The actual syncing happens
+ * in GPUProcessManager, and so this class should not be used directly.
+ */
+class LayerTreeOwnerTracker final {
+ public:
+  static void Initialize();
+  static void Shutdown();
+  static LayerTreeOwnerTracker* Get();
+
+  /**
+   * Map aLayersId and aProcessId together so that that process
+   * can access that layer tree.
+   */
+  void Map(LayersId aLayersId, base::ProcessId aProcessId);
+
+  /**
+   * Remove an existing mapping.
+   */
+  void Unmap(LayersId aLayersId, base::ProcessId aProcessId);
+
+  /**
+   * Checks whether it is okay for aProcessId to access aLayersId.
+   */
+  bool IsMapped(LayersId aLayersId, base::ProcessId aProcessId);
+
+  void Iterate(
+      const std::function<void(LayersId aLayersId, base::ProcessId aProcessId)>&
+          aCallback);
+
+ private:
+  LayerTreeOwnerTracker();
+
+  mozilla::Mutex mLayerIdsLock MOZ_UNANNOTATED;
+  std::map<LayersId, base::ProcessId> mLayerIds;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_LayerTreeOwnerTracker_h
diff --git a/gfx/layers/ipc/LayersMessageUtils.h b/gfx/layers/ipc/LayersMessageUtils.h
new file mode 100644
index 0000000000..d869d4ed83
--- /dev/null
+++ b/gfx/layers/ipc/LayersMessageUtils.h
@@ -0,0 +1,1180 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_LayersMessageUtils
+#define mozilla_layers_LayersMessageUtils
+
+#include <stdint.h>
+
+#include <utility>
+
+#include "FrameMetrics.h"
+#include "VsyncSource.h"
+#include "chrome/common/ipc_message_utils.h"
+#include "ipc/EnumSerializer.h"
+#include "ipc/IPCMessageUtils.h"
+#include "mozilla/ScrollSnapInfo.h"
+#include "mozilla/ServoBindings.h"
+#include "mozilla/ipc/ByteBuf.h"
+#include "mozilla/ipc/ProtocolMessageUtils.h"
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/AsyncDragMetrics.h"
+#include "mozilla/layers/CompositorOptions.h"
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/FocusTarget.h"
+#include "mozilla/layers/GeckoContentControllerTypes.h"
+#include "mozilla/layers/KeyboardMap.h"
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/layers/MatrixMessage.h"
+#include "mozilla/layers/OverlayInfo.h"
+#include "mozilla/layers/RepaintRequest.h"
+#include "mozilla/layers/ScrollbarData.h"
+#include "nsSize.h"
+#include "mozilla/layers/DoubleTapToZoom.h"
+
+// For ParamTraits, could be moved to cpp file
+#include "ipc/nsGUIEventIPC.h"
+#include "mozilla/GfxMessageUtils.h"
+#include "mozilla/ipc/ByteBufUtils.h"
+
+#ifdef _MSC_VER
+#  pragma warning(disable : 4800)
+#endif
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::layers::LayersId>
+    : public PlainOldDataSerializer<mozilla::layers::LayersId> {};
+
+template <typename T>
+struct ParamTraits<mozilla::layers::BaseTransactionId<T>>
+    : public PlainOldDataSerializer<mozilla::layers::BaseTransactionId<T>> {};
+
+template <>
+struct ParamTraits<mozilla::VsyncId>
+    : public PlainOldDataSerializer<mozilla::VsyncId> {};
+
+template <>
+struct ParamTraits<mozilla::VsyncEvent> {
+  typedef mozilla::VsyncEvent paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mId);
+    WriteParam(writer, param.mTime);
+    WriteParam(writer, param.mOutputTime);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mId) &&
+           ReadParam(reader, &result->mTime) &&
+           ReadParam(reader, &result->mOutputTime);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::MatrixMessage> {
+  typedef mozilla::layers::MatrixMessage paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mMatrix);
+    WriteParam(aWriter, aParam.mTopLevelViewportVisibleRectInBrowserCoords);
+    WriteParam(aWriter, aParam.mLayersId);
+  }
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mMatrix) &&
+           ReadParam(aReader,
+                     &aResult->mTopLevelViewportVisibleRectInBrowserCoords) &&
+           ReadParam(aReader, &aResult->mLayersId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::WindowKind>
+    : public ContiguousEnumSerializer<mozilla::layers::WindowKind,
+                                      mozilla::layers::WindowKind::MAIN,
+                                      mozilla::layers::WindowKind::LAST> {};
+
+template <>
+struct ParamTraits<mozilla::layers::LayersBackend>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::LayersBackend,
+          mozilla::layers::LayersBackend::LAYERS_NONE,
+          mozilla::layers::LayersBackend::LAYERS_LAST> {};
+
+template <>
+struct ParamTraits<mozilla::layers::WebRenderBackend>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::WebRenderBackend,
+          mozilla::layers::WebRenderBackend::HARDWARE,
+          mozilla::layers::WebRenderBackend::LAST> {};
+
+template <>
+struct ParamTraits<mozilla::layers::WebRenderCompositor>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::WebRenderCompositor,
+          mozilla::layers::WebRenderCompositor::DRAW,
+          mozilla::layers::WebRenderCompositor::LAST> {};
+
+template <>
+struct ParamTraits<mozilla::layers::TextureType>
+    : public ContiguousEnumSerializer<mozilla::layers::TextureType,
+                                      mozilla::layers::TextureType::Unknown,
+                                      mozilla::layers::TextureType::Last> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ScaleMode>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::ScaleMode, mozilla::layers::ScaleMode::SCALE_NONE,
+          mozilla::layers::kHighestScaleMode> {};
+
+template <>
+struct ParamTraits<mozilla::StyleScrollSnapStrictness>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::StyleScrollSnapStrictness,
+          mozilla::StyleScrollSnapStrictness::None,
+          mozilla::StyleScrollSnapStrictness::Proximity> {};
+
+template <>
+struct ParamTraits<mozilla::layers::TextureFlags>
+    : public BitFlagsEnumSerializer<mozilla::layers::TextureFlags,
+                                    mozilla::layers::TextureFlags::ALL_BITS> {};
+
+template <>
+struct ParamTraits<mozilla::layers::DiagnosticTypes>
+    : public BitFlagsEnumSerializer<
+          mozilla::layers::DiagnosticTypes,
+          mozilla::layers::DiagnosticTypes::ALL_BITS> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollDirection>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::ScrollDirection,
+          mozilla::layers::ScrollDirection::eVertical,
+          mozilla::layers::kHighestScrollDirection> {};
+
+template <>
+struct ParamTraits<mozilla::layers::FrameMetrics::ScrollOffsetUpdateType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::FrameMetrics::ScrollOffsetUpdateType,
+          mozilla::layers::FrameMetrics::ScrollOffsetUpdateType::eNone,
+          mozilla::layers::FrameMetrics::sHighestScrollOffsetUpdateType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::RepaintRequest::ScrollOffsetUpdateType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::RepaintRequest::ScrollOffsetUpdateType,
+          mozilla::layers::RepaintRequest::ScrollOffsetUpdateType::eNone,
+          mozilla::layers::RepaintRequest::sHighestScrollOffsetUpdateType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::OverscrollBehavior>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::OverscrollBehavior,
+          mozilla::layers::OverscrollBehavior::Auto,
+          mozilla::layers::kHighestOverscrollBehavior> {};
+
+template <>
+struct ParamTraits<mozilla::layers::LayerHandle> {
+  typedef mozilla::layers::LayerHandle paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mHandle);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mHandle);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositableHandle> {
+  typedef mozilla::layers::CompositableHandle paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mHandle);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mHandle);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositableHandleOwner>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::CompositableHandleOwner,
+          mozilla::layers::CompositableHandleOwner::WebRenderBridge,
+          mozilla::layers::CompositableHandleOwner::ImageBridge> {};
+
+template <>
+struct ParamTraits<mozilla::layers::RemoteTextureId> {
+  typedef mozilla::layers::RemoteTextureId paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mId);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::RemoteTextureOwnerId> {
+  typedef mozilla::layers::RemoteTextureOwnerId paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mId);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::GpuProcessTextureId> {
+  typedef mozilla::layers::GpuProcessTextureId paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mId);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::GpuProcessQueryId> {
+  typedef mozilla::layers::GpuProcessQueryId paramType;
+
+  static void Write(MessageWriter* writer, const paramType& param) {
+    WriteParam(writer, param.mId);
+  }
+  static bool Read(MessageReader* reader, paramType* result) {
+    return ReadParam(reader, &result->mId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::FrameMetrics>
+    : BitfieldHelper<mozilla::layers::FrameMetrics> {
+  typedef mozilla::layers::FrameMetrics paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mScrollId);
+    WriteParam(aWriter, aParam.mPresShellResolution);
+    WriteParam(aWriter, aParam.mCompositionBounds);
+    WriteParam(aWriter, aParam.mCompositionBoundsWidthIgnoringScrollbars);
+    WriteParam(aWriter, aParam.mDisplayPort);
+    WriteParam(aWriter, aParam.mScrollableRect);
+    WriteParam(aWriter, aParam.mCumulativeResolution);
+    WriteParam(aWriter, aParam.mDevPixelsPerCSSPixel);
+    WriteParam(aWriter, aParam.mScrollOffset);
+    WriteParam(aWriter, aParam.mZoom);
+    WriteParam(aWriter, aParam.mScrollGeneration);
+    WriteParam(aWriter, aParam.mBoundingCompositionSize);
+    WriteParam(aWriter, aParam.mPresShellId);
+    WriteParam(aWriter, aParam.mLayoutViewport);
+    WriteParam(aWriter, aParam.mTransformToAncestorScale);
+    WriteParam(aWriter, aParam.mPaintRequestTime);
+    WriteParam(aWriter, aParam.mVisualDestination);
+    WriteParam(aWriter, aParam.mVisualScrollUpdateType);
+    WriteParam(aWriter, aParam.mFixedLayerMargins);
+    WriteParam(aWriter, aParam.mCompositionSizeWithoutDynamicToolbar);
+    WriteParam(aWriter, aParam.mIsRootContent);
+    WriteParam(aWriter, aParam.mIsScrollInfoLayer);
+    WriteParam(aWriter, aParam.mHasNonZeroDisplayPortMargins);
+    WriteParam(aWriter, aParam.mMinimalDisplayPort);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (
+        ReadParam(aReader, &aResult->mScrollId) &&
+        ReadParam(aReader, &aResult->mPresShellResolution) &&
+        ReadParam(aReader, &aResult->mCompositionBounds) &&
+        ReadParam(aReader,
+                  &aResult->mCompositionBoundsWidthIgnoringScrollbars) &&
+        ReadParam(aReader, &aResult->mDisplayPort) &&
+        ReadParam(aReader, &aResult->mScrollableRect) &&
+        ReadParam(aReader, &aResult->mCumulativeResolution) &&
+        ReadParam(aReader, &aResult->mDevPixelsPerCSSPixel) &&
+        ReadParam(aReader, &aResult->mScrollOffset) &&
+        ReadParam(aReader, &aResult->mZoom) &&
+        ReadParam(aReader, &aResult->mScrollGeneration) &&
+        ReadParam(aReader, &aResult->mBoundingCompositionSize) &&
+        ReadParam(aReader, &aResult->mPresShellId) &&
+        ReadParam(aReader, &aResult->mLayoutViewport) &&
+        ReadParam(aReader, &aResult->mTransformToAncestorScale) &&
+        ReadParam(aReader, &aResult->mPaintRequestTime) &&
+        ReadParam(aReader, &aResult->mVisualDestination) &&
+        ReadParam(aReader, &aResult->mVisualScrollUpdateType) &&
+        ReadParam(aReader, &aResult->mFixedLayerMargins) &&
+        ReadParam(aReader, &aResult->mCompositionSizeWithoutDynamicToolbar) &&
+        ReadBoolForBitfield(aReader, aResult, &paramType::SetIsRootContent) &&
+        ReadBoolForBitfield(aReader, aResult,
+                            &paramType::SetIsScrollInfoLayer) &&
+        ReadBoolForBitfield(aReader, aResult,
+                            &paramType::SetHasNonZeroDisplayPortMargins) &&
+        ReadBoolForBitfield(aReader, aResult,
+                            &paramType::SetMinimalDisplayPort));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::APZScrollAnimationType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::APZScrollAnimationType, mozilla::APZScrollAnimationType::No,
+          mozilla::APZScrollAnimationType::TriggeredByUserInput> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollSnapTargetIds> {
+  typedef mozilla::ScrollSnapTargetIds paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mIdsOnX);
+    WriteParam(aWriter, aParam.mIdsOnY);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mIdsOnX) &&
+           ReadParam(aReader, &aResult->mIdsOnY);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::RepaintRequest>
+    : BitfieldHelper<mozilla::layers::RepaintRequest> {
+  typedef mozilla::layers::RepaintRequest paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mScrollId);
+    WriteParam(aWriter, aParam.mPresShellResolution);
+    WriteParam(aWriter, aParam.mCompositionBounds);
+    WriteParam(aWriter, aParam.mCumulativeResolution);
+    WriteParam(aWriter, aParam.mDevPixelsPerCSSPixel);
+    WriteParam(aWriter, aParam.mScrollOffset);
+    WriteParam(aWriter, aParam.mZoom);
+    WriteParam(aWriter, aParam.mScrollGeneration);
+    WriteParam(aWriter, aParam.mScrollGenerationOnApz);
+    WriteParam(aWriter, aParam.mDisplayPortMargins);
+    WriteParam(aWriter, aParam.mPresShellId);
+    WriteParam(aWriter, aParam.mLayoutViewport);
+    WriteParam(aWriter, aParam.mTransformToAncestorScale);
+    WriteParam(aWriter, aParam.mPaintRequestTime);
+    WriteParam(aWriter, aParam.mScrollUpdateType);
+    WriteParam(aWriter, aParam.mScrollAnimationType);
+    WriteParam(aWriter, aParam.mLastSnapTargetIds);
+    WriteParam(aWriter, aParam.mIsRootContent);
+    WriteParam(aWriter, aParam.mIsScrollInfoLayer);
+    WriteParam(aWriter, aParam.mIsInScrollingGesture);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (
+        ReadParam(aReader, &aResult->mScrollId) &&
+        ReadParam(aReader, &aResult->mPresShellResolution) &&
+        ReadParam(aReader, &aResult->mCompositionBounds) &&
+        ReadParam(aReader, &aResult->mCumulativeResolution) &&
+        ReadParam(aReader, &aResult->mDevPixelsPerCSSPixel) &&
+        ReadParam(aReader, &aResult->mScrollOffset) &&
+        ReadParam(aReader, &aResult->mZoom) &&
+        ReadParam(aReader, &aResult->mScrollGeneration) &&
+        ReadParam(aReader, &aResult->mScrollGenerationOnApz) &&
+        ReadParam(aReader, &aResult->mDisplayPortMargins) &&
+        ReadParam(aReader, &aResult->mPresShellId) &&
+        ReadParam(aReader, &aResult->mLayoutViewport) &&
+        ReadParam(aReader, &aResult->mTransformToAncestorScale) &&
+        ReadParam(aReader, &aResult->mPaintRequestTime) &&
+        ReadParam(aReader, &aResult->mScrollUpdateType) &&
+        ReadParam(aReader, &aResult->mScrollAnimationType) &&
+        ReadParam(aReader, &aResult->mLastSnapTargetIds) &&
+        ReadBoolForBitfield(aReader, aResult, &paramType::SetIsRootContent) &&
+        ReadBoolForBitfield(aReader, aResult,
+                            &paramType::SetIsScrollInfoLayer) &&
+        ReadBoolForBitfield(aReader, aResult,
+                            &paramType::SetIsInScrollingGesture));
+  }
+};
+
+template <>
+struct ParamTraits<nsSize> {
+  typedef nsSize paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.width);
+    WriteParam(aWriter, aParam.height);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->width) &&
+           ReadParam(aReader, &aResult->height);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::StyleScrollSnapStop>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::StyleScrollSnapStop, mozilla::StyleScrollSnapStop::Normal,
+          mozilla::StyleScrollSnapStop::Always> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollSnapTargetId>
+    : public PlainOldDataSerializer<mozilla::ScrollSnapTargetId> {};
+
+template <>
+struct ParamTraits<mozilla::SnapPoint> {
+  typedef mozilla::SnapPoint paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mX);
+    WriteParam(aWriter, aParam.mY);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mX) && ReadParam(aReader, &aResult->mY);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::ScrollSnapInfo::SnapTarget> {
+  typedef mozilla::ScrollSnapInfo::SnapTarget paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mSnapPoint);
+    WriteParam(aWriter, aParam.mSnapArea);
+    WriteParam(aWriter, aParam.mScrollSnapStop);
+    WriteParam(aWriter, aParam.mTargetId);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mSnapPoint) &&
+           ReadParam(aReader, &aResult->mSnapArea) &&
+           ReadParam(aReader, &aResult->mScrollSnapStop) &&
+           ReadParam(aReader, &aResult->mTargetId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::ScrollSnapInfo::ScrollSnapRange> {
+  typedef mozilla::ScrollSnapInfo::ScrollSnapRange paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mDirection);
+    WriteParam(aWriter, aParam.mSnapArea);
+    WriteParam(aWriter, aParam.mTargetId);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mDirection) &&
+           ReadParam(aReader, &aResult->mSnapArea) &&
+           ReadParam(aReader, &aResult->mTargetId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::ScrollSnapInfo> {
+  typedef mozilla::ScrollSnapInfo paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mScrollSnapStrictnessX);
+    WriteParam(aWriter, aParam.mScrollSnapStrictnessY);
+    WriteParam(aWriter, aParam.mSnapTargets);
+    WriteParam(aWriter, aParam.mXRangeWiderThanSnapport);
+    WriteParam(aWriter, aParam.mYRangeWiderThanSnapport);
+    WriteParam(aWriter, aParam.mSnapportSize);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mScrollSnapStrictnessX) &&
+            ReadParam(aReader, &aResult->mScrollSnapStrictnessY) &&
+            ReadParam(aReader, &aResult->mSnapTargets) &&
+            ReadParam(aReader, &aResult->mXRangeWiderThanSnapport) &&
+            ReadParam(aReader, &aResult->mYRangeWiderThanSnapport) &&
+            ReadParam(aReader, &aResult->mSnapportSize));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::OverscrollBehaviorInfo> {
+  // Not using PlainOldDataSerializer so we get enum validation
+  // for the members.
+
+  typedef mozilla::layers::OverscrollBehaviorInfo paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mBehaviorX);
+    WriteParam(aWriter, aParam.mBehaviorY);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mBehaviorX) &&
+            ReadParam(aReader, &aResult->mBehaviorY));
+  }
+};
+
+template <typename T>
+struct ParamTraits<mozilla::ScrollGeneration<T>>
+    : PlainOldDataSerializer<mozilla::ScrollGeneration<T>> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollUpdateType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::ScrollUpdateType, mozilla::ScrollUpdateType::Absolute,
+          mozilla::ScrollUpdateType::MergeableAbsolute> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollMode>
+    : public ContiguousEnumSerializerInclusive<mozilla::ScrollMode,
+                                               mozilla::ScrollMode::Instant,
+                                               mozilla::ScrollMode::Normal> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollOrigin>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::ScrollOrigin, mozilla::ScrollOrigin::None,
+          mozilla::ScrollOrigin::Scrollbars> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollTriggeredByScript>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::ScrollTriggeredByScript,
+          mozilla::ScrollTriggeredByScript::No,
+          mozilla::ScrollTriggeredByScript::Yes> {};
+
+template <>
+struct ParamTraits<mozilla::ScrollPositionUpdate> {
+  typedef mozilla::ScrollPositionUpdate paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mScrollGeneration);
+    WriteParam(aWriter, aParam.mType);
+    WriteParam(aWriter, aParam.mScrollMode);
+    WriteParam(aWriter, aParam.mScrollOrigin);
+    WriteParam(aWriter, aParam.mDestination);
+    WriteParam(aWriter, aParam.mSource);
+    WriteParam(aWriter, aParam.mDelta);
+    WriteParam(aWriter, aParam.mTriggeredByScript);
+    WriteParam(aWriter, aParam.mSnapTargetIds);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mScrollGeneration) &&
+           ReadParam(aReader, &aResult->mType) &&
+           ReadParam(aReader, &aResult->mScrollMode) &&
+           ReadParam(aReader, &aResult->mScrollOrigin) &&
+           ReadParam(aReader, &aResult->mDestination) &&
+           ReadParam(aReader, &aResult->mSource) &&
+           ReadParam(aReader, &aResult->mDelta) &&
+           ReadParam(aReader, &aResult->mTriggeredByScript) &&
+           ReadParam(aReader, &aResult->mSnapTargetIds);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollMetadata>
+    : BitfieldHelper<mozilla::layers::ScrollMetadata> {
+  typedef mozilla::layers::ScrollMetadata paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mMetrics);
+    WriteParam(aWriter, aParam.mSnapInfo);
+    WriteParam(aWriter, aParam.mScrollParentId);
+    WriteParam(aWriter, aParam.GetContentDescription());
+    WriteParam(aWriter, aParam.mLineScrollAmount);
+    WriteParam(aWriter, aParam.mPageScrollAmount);
+    WriteParam(aWriter, aParam.mHasScrollgrab);
+    WriteParam(aWriter, aParam.mIsLayersIdRoot);
+    WriteParam(aWriter, aParam.mIsAutoDirRootContentRTL);
+    WriteParam(aWriter, aParam.mForceDisableApz);
+    WriteParam(aWriter, aParam.mResolutionUpdated);
+    WriteParam(aWriter, aParam.mIsRDMTouchSimulationActive);
+    WriteParam(aWriter, aParam.mDidContentGetPainted);
+    WriteParam(aWriter, aParam.mForceMousewheelAutodir);
+    WriteParam(aWriter, aParam.mForceMousewheelAutodirHonourRoot);
+    WriteParam(aWriter, aParam.mIsPaginatedPresentation);
+    WriteParam(aWriter, aParam.mDisregardedDirection);
+    WriteParam(aWriter, aParam.mOverscrollBehavior);
+    WriteParam(aWriter, aParam.mScrollUpdates);
+  }
+
+  static bool ReadContentDescription(MessageReader* aReader,
+                                     paramType* aResult) {
+    nsCString str;
+    if (!ReadParam(aReader, &str)) {
+      return false;
+    }
+    aResult->SetContentDescription(str);
+    return true;
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mMetrics) &&
+            ReadParam(aReader, &aResult->mSnapInfo) &&
+            ReadParam(aReader, &aResult->mScrollParentId) &&
+            ReadContentDescription(aReader, aResult) &&
+            ReadParam(aReader, &aResult->mLineScrollAmount) &&
+            ReadParam(aReader, &aResult->mPageScrollAmount) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetHasScrollgrab) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetIsLayersIdRoot) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetIsAutoDirRootContentRTL) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetForceDisableApz) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetResolutionUpdated) &&
+            ReadBoolForBitfield(aReader, aResult,
+                                &paramType::SetIsRDMTouchSimulationActive)) &&
+           ReadBoolForBitfield(aReader, aResult,
+                               &paramType::SetDidContentGetPainted) &&
+           ReadBoolForBitfield(aReader, aResult,
+                               &paramType::SetForceMousewheelAutodir) &&
+           ReadBoolForBitfield(
+               aReader, aResult,
+               &paramType::SetForceMousewheelAutodirHonourRoot) &&
+           ReadBoolForBitfield(aReader, aResult,
+                               &paramType::SetIsPaginatedPresentation) &&
+           ReadParam(aReader, &aResult->mDisregardedDirection) &&
+           ReadParam(aReader, &aResult->mOverscrollBehavior) &&
+           ReadParam(aReader, &aResult->mScrollUpdates);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::TextureFactoryIdentifier> {
+  typedef mozilla::layers::TextureFactoryIdentifier paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mParentBackend);
+    WriteParam(aWriter, aParam.mWebRenderBackend);
+    WriteParam(aWriter, aParam.mWebRenderCompositor);
+    WriteParam(aWriter, aParam.mParentProcessType);
+    WriteParam(aWriter, aParam.mMaxTextureSize);
+    WriteParam(aWriter, aParam.mCompositorUseANGLE);
+    WriteParam(aWriter, aParam.mCompositorUseDComp);
+    WriteParam(aWriter, aParam.mUseCompositorWnd);
+    WriteParam(aWriter, aParam.mSupportsTextureBlitting);
+    WriteParam(aWriter, aParam.mSupportsPartialUploads);
+    WriteParam(aWriter, aParam.mSupportsComponentAlpha);
+    WriteParam(aWriter, aParam.mSupportsD3D11NV12);
+    WriteParam(aWriter, aParam.mSyncHandle);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    bool result = ReadParam(aReader, &aResult->mParentBackend) &&
+                  ReadParam(aReader, &aResult->mWebRenderBackend) &&
+                  ReadParam(aReader, &aResult->mWebRenderCompositor) &&
+                  ReadParam(aReader, &aResult->mParentProcessType) &&
+                  ReadParam(aReader, &aResult->mMaxTextureSize) &&
+                  ReadParam(aReader, &aResult->mCompositorUseANGLE) &&
+                  ReadParam(aReader, &aResult->mCompositorUseDComp) &&
+                  ReadParam(aReader, &aResult->mUseCompositorWnd) &&
+                  ReadParam(aReader, &aResult->mSupportsTextureBlitting) &&
+                  ReadParam(aReader, &aResult->mSupportsPartialUploads) &&
+                  ReadParam(aReader, &aResult->mSupportsComponentAlpha) &&
+                  ReadParam(aReader, &aResult->mSupportsD3D11NV12) &&
+                  ReadParam(aReader, &aResult->mSyncHandle);
+    return result;
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::TextureInfo> {
+  typedef mozilla::layers::TextureInfo paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mCompositableType);
+    WriteParam(aWriter, aParam.mTextureFlags);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mCompositableType) &&
+           ReadParam(aReader, &aResult->mTextureFlags);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositableType>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::CompositableType,
+          mozilla::layers::CompositableType::UNKNOWN,
+          mozilla::layers::CompositableType::COUNT> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollableLayerGuid> {
+  typedef mozilla::layers::ScrollableLayerGuid paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mLayersId);
+    WriteParam(aWriter, aParam.mPresShellId);
+    WriteParam(aWriter, aParam.mScrollId);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mLayersId) &&
+            ReadParam(aReader, &aResult->mPresShellId) &&
+            ReadParam(aReader, &aResult->mScrollId));
+  }
+};
+
+template <>
+struct ParamTraits<nsEventStatus>
+    : public ContiguousEnumSerializer<nsEventStatus, nsEventStatus_eIgnore,
+                                      nsEventStatus_eSentinel> {};
+
+template <>
+struct ParamTraits<mozilla::layers::APZHandledPlace>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::APZHandledPlace,
+          mozilla::layers::APZHandledPlace::Unhandled,
+          mozilla::layers::APZHandledPlace::Last> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollDirections> {
+  typedef mozilla::layers::ScrollDirections paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.serialize());
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    uint8_t value;
+    if (!ReadParam(aReader, &value)) {
+      return false;
+    }
+    aResult->deserialize(value);
+    return true;
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::APZHandledResult> {
+  typedef mozilla::layers::APZHandledResult paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mPlace);
+    WriteParam(aWriter, aParam.mScrollableDirections);
+    WriteParam(aWriter, aParam.mOverscrollDirections);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mPlace) &&
+            ReadParam(aReader, &aResult->mScrollableDirections) &&
+            ReadParam(aReader, &aResult->mOverscrollDirections));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::APZEventResult> {
+  typedef mozilla::layers::APZEventResult paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.GetStatus());
+    WriteParam(aWriter, aParam.GetHandledResult());
+    WriteParam(aWriter, aParam.mTargetGuid);
+    WriteParam(aWriter, aParam.mInputBlockId);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    nsEventStatus status;
+    if (!ReadParam(aReader, &status)) {
+      return false;
+    }
+    aResult->UpdateStatus(status);
+
+    mozilla::Maybe<mozilla::layers::APZHandledResult> handledResult;
+    if (!ReadParam(aReader, &handledResult)) {
+      return false;
+    }
+    aResult->UpdateHandledResult(handledResult);
+
+    return (ReadParam(aReader, &aResult->mTargetGuid) &&
+            ReadParam(aReader, &aResult->mInputBlockId));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::ZoomConstraints> {
+  typedef mozilla::layers::ZoomConstraints paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mAllowZoom);
+    WriteParam(aWriter, aParam.mAllowDoubleTapZoom);
+    WriteParam(aWriter, aParam.mMinZoom);
+    WriteParam(aWriter, aParam.mMaxZoom);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mAllowZoom) &&
+            ReadParam(aReader, &aResult->mAllowDoubleTapZoom) &&
+            ReadParam(aReader, &aResult->mMinZoom) &&
+            ReadParam(aReader, &aResult->mMaxZoom));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::FocusTarget::ScrollTargets> {
+  typedef mozilla::layers::FocusTarget::ScrollTargets paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mHorizontal);
+    WriteParam(aWriter, aParam.mVertical);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mHorizontal) &&
+           ReadParam(aReader, &aResult->mVertical);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::FocusTarget::NoFocusTarget>
+    : public EmptyStructSerializer<
+          mozilla::layers::FocusTarget::NoFocusTarget> {};
+
+template <>
+struct ParamTraits<mozilla::layers::FocusTarget> {
+  typedef mozilla::layers::FocusTarget paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mSequenceNumber);
+    WriteParam(aWriter, aParam.mFocusHasKeyEventListeners);
+    WriteParam(aWriter, aParam.mData);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    if (!ReadParam(aReader, &aResult->mSequenceNumber) ||
+        !ReadParam(aReader, &aResult->mFocusHasKeyEventListeners) ||
+        !ReadParam(aReader, &aResult->mData)) {
+      return false;
+    }
+    return true;
+  }
+};
+
+template <>
+struct ParamTraits<
+    mozilla::layers::KeyboardScrollAction::KeyboardScrollActionType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::KeyboardScrollAction::KeyboardScrollActionType,
+          mozilla::layers::KeyboardScrollAction::KeyboardScrollActionType::
+              eScrollCharacter,
+          mozilla::layers::KeyboardScrollAction::
+              sHighestKeyboardScrollActionType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::KeyboardScrollAction> {
+  typedef mozilla::layers::KeyboardScrollAction paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mType);
+    WriteParam(aWriter, aParam.mForward);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mType) &&
+           ReadParam(aReader, &aResult->mForward);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::KeyboardShortcut> {
+  typedef mozilla::layers::KeyboardShortcut paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mAction);
+    WriteParam(aWriter, aParam.mKeyCode);
+    WriteParam(aWriter, aParam.mCharCode);
+    WriteParam(aWriter, aParam.mModifiers);
+    WriteParam(aWriter, aParam.mModifiersMask);
+    WriteParam(aWriter, aParam.mEventType);
+    WriteParam(aWriter, aParam.mDispatchToContent);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mAction) &&
+           ReadParam(aReader, &aResult->mKeyCode) &&
+           ReadParam(aReader, &aResult->mCharCode) &&
+           ReadParam(aReader, &aResult->mModifiers) &&
+           ReadParam(aReader, &aResult->mModifiersMask) &&
+           ReadParam(aReader, &aResult->mEventType) &&
+           ReadParam(aReader, &aResult->mDispatchToContent);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::KeyboardMap> {
+  typedef mozilla::layers::KeyboardMap paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.Shortcuts());
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    nsTArray<mozilla::layers::KeyboardShortcut> shortcuts;
+    if (!ReadParam(aReader, &shortcuts)) {
+      return false;
+    }
+    *aResult = mozilla::layers::KeyboardMap(std::move(shortcuts));
+    return true;
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::GeckoContentController_TapType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::GeckoContentController_TapType,
+          mozilla::layers::GeckoContentController_TapType::eSingleTap,
+          mozilla::layers::kHighestGeckoContentController_TapType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::GeckoContentController_APZStateChange>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::GeckoContentController_APZStateChange,
+          mozilla::layers::GeckoContentController_APZStateChange::
+              eTransformBegin,
+          mozilla::layers::kHighestGeckoContentController_APZStateChange> {};
+
+template <>
+struct ParamTraits<mozilla::layers::EventRegionsOverride>
+    : public BitFlagsEnumSerializer<
+          mozilla::layers::EventRegionsOverride,
+          mozilla::layers::EventRegionsOverride::ALL_BITS> {};
+
+template <>
+struct ParamTraits<mozilla::layers::AsyncDragMetrics> {
+  typedef mozilla::layers::AsyncDragMetrics paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mViewId);
+    WriteParam(aWriter, aParam.mPresShellId);
+    WriteParam(aWriter, aParam.mDragStartSequenceNumber);
+    WriteParam(aWriter, aParam.mScrollbarDragOffset);
+    WriteParam(aWriter, aParam.mDirection);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mViewId) &&
+            ReadParam(aReader, &aResult->mPresShellId) &&
+            ReadParam(aReader, &aResult->mDragStartSequenceNumber) &&
+            ReadParam(aReader, &aResult->mScrollbarDragOffset) &&
+            ReadParam(aReader, &aResult->mDirection));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::BrowserGestureResponse>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::BrowserGestureResponse,
+          mozilla::layers::BrowserGestureResponse::NotConsumed,
+          mozilla::layers::BrowserGestureResponse::Consumed> {};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositorOptions> {
+  typedef mozilla::layers::CompositorOptions paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mUseAPZ);
+    WriteParam(aWriter, aParam.mUseSoftwareWebRender);
+    WriteParam(aWriter, aParam.mAllowSoftwareWebRenderD3D11);
+    WriteParam(aWriter, aParam.mAllowSoftwareWebRenderOGL);
+    WriteParam(aWriter, aParam.mInitiallyPaused);
+    WriteParam(aWriter, aParam.mNeedFastSnaphot);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mUseAPZ) &&
+           ReadParam(aReader, &aResult->mUseSoftwareWebRender) &&
+           ReadParam(aReader, &aResult->mAllowSoftwareWebRenderD3D11) &&
+           ReadParam(aReader, &aResult->mAllowSoftwareWebRenderOGL) &&
+           ReadParam(aReader, &aResult->mInitiallyPaused) &&
+           ReadParam(aReader, &aResult->mNeedFastSnaphot);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::OverlaySupportType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::OverlaySupportType,
+          mozilla::layers::OverlaySupportType::None,
+          mozilla::layers::OverlaySupportType::MAX> {};
+
+template <>
+struct ParamTraits<mozilla::layers::OverlayInfo> {
+  typedef mozilla::layers::OverlayInfo paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mSupportsOverlays);
+    WriteParam(aWriter, aParam.mNv12Overlay);
+    WriteParam(aWriter, aParam.mYuy2Overlay);
+    WriteParam(aWriter, aParam.mBgra8Overlay);
+    WriteParam(aWriter, aParam.mRgb10a2Overlay);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mSupportsOverlays) &&
+           ReadParam(aReader, &aResult->mNv12Overlay) &&
+           ReadParam(aReader, &aResult->mYuy2Overlay) &&
+           ReadParam(aReader, &aResult->mBgra8Overlay) &&
+           ReadParam(aReader, &aResult->mRgb10a2Overlay);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::SwapChainInfo> {
+  typedef mozilla::layers::SwapChainInfo paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mTearingSupported);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mTearingSupported);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollbarLayerType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::ScrollbarLayerType,
+          mozilla::layers::ScrollbarLayerType::None,
+          mozilla::layers::kHighestScrollbarLayerType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ScrollbarData> {
+  typedef mozilla::layers::ScrollbarData paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mDirection);
+    WriteParam(aWriter, aParam.mScrollbarLayerType);
+    WriteParam(aWriter, aParam.mThumbRatio);
+    WriteParam(aWriter, aParam.mThumbStart);
+    WriteParam(aWriter, aParam.mThumbLength);
+    WriteParam(aWriter, aParam.mThumbMinLength);
+    WriteParam(aWriter, aParam.mThumbIsAsyncDraggable);
+    WriteParam(aWriter, aParam.mScrollTrackStart);
+    WriteParam(aWriter, aParam.mScrollTrackLength);
+    WriteParam(aWriter, aParam.mTargetViewId);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mDirection) &&
+           ReadParam(aReader, &aResult->mScrollbarLayerType) &&
+           ReadParam(aReader, &aResult->mThumbRatio) &&
+           ReadParam(aReader, &aResult->mThumbStart) &&
+           ReadParam(aReader, &aResult->mThumbLength) &&
+           ReadParam(aReader, &aResult->mThumbMinLength) &&
+           ReadParam(aReader, &aResult->mThumbIsAsyncDraggable) &&
+           ReadParam(aReader, &aResult->mScrollTrackStart) &&
+           ReadParam(aReader, &aResult->mScrollTrackLength) &&
+           ReadParam(aReader, &aResult->mTargetViewId);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositionPayloadType>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::CompositionPayloadType,
+          mozilla::layers::CompositionPayloadType::eKeyPress,
+          mozilla::layers::kHighestCompositionPayloadType> {};
+
+template <>
+struct ParamTraits<mozilla::layers::CompositionPayload> {
+  typedef mozilla::layers::CompositionPayload paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mType);
+    WriteParam(aWriter, aParam.mTimeStamp);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mType) &&
+           ReadParam(aReader, &aResult->mTimeStamp);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::CantZoomOutBehavior>
+    : public ContiguousEnumSerializerInclusive<
+          mozilla::layers::CantZoomOutBehavior,
+          mozilla::layers::CantZoomOutBehavior::Nothing,
+          mozilla::layers::CantZoomOutBehavior::ZoomIn> {};
+
+template <>
+struct ParamTraits<mozilla::layers::ZoomTarget> {
+  typedef mozilla::layers::ZoomTarget paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.targetRect);
+    WriteParam(aWriter, aParam.cantZoomOutBehavior);
+    WriteParam(aWriter, aParam.elementBoundingRect);
+    WriteParam(aWriter, aParam.documentRelativePointerPosition);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->targetRect) &&
+            ReadParam(aReader, &aResult->cantZoomOutBehavior) &&
+            ReadParam(aReader, &aResult->elementBoundingRect) &&
+            ReadParam(aReader, &aResult->documentRelativePointerPosition));
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::DoubleTapToZoomMetrics> {
+  typedef mozilla::layers::DoubleTapToZoomMetrics paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mVisualViewport);
+    WriteParam(aWriter, aParam.mRootScrollableRect);
+    WriteParam(aWriter, aParam.mTransformMatrix);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return (ReadParam(aReader, &aResult->mVisualViewport) &&
+            ReadParam(aReader, &aResult->mRootScrollableRect) &&
+            ReadParam(aReader, &aResult->mTransformMatrix));
+  }
+};
+
+#define IMPL_PARAMTRAITS_BY_SERDE(type_)                                    \
+  template <>                                                               \
+  struct ParamTraits<mozilla::type_> {                                      \
+    typedef mozilla::type_ paramType;                                       \
+    static void Write(MessageWriter* aWriter, const paramType& aParam) {    \
+      mozilla::ipc::ByteBuf v;                                              \
+      mozilla::DebugOnly<bool> rv = Servo_##type_##_Serialize(&aParam, &v); \
+      MOZ_ASSERT(rv, "Serialize ##type_## failed");                         \
+      WriteParam(aWriter, std::move(v));                                    \
+    }                                                                       \
+    static ReadResult<paramType> Read(MessageReader* aReader) {             \
+      mozilla::ipc::ByteBuf in;                                             \
+      ReadResult<paramType> result;                                         \
+      if (!ReadParam(aReader, &in) || !in.mData) {                          \
+        return result;                                                      \
+      }                                                                     \
+      /* TODO: Should be able to initialize `result` in-place instead */    \
+      mozilla::AlignedStorage2<paramType> value;                            \
+      if (!Servo_##type_##_Deserialize(&in, value.addr())) {                \
+        return result;                                                      \
+      }                                                                     \
+      result = std::move(*value.addr());                                    \
+      value.addr()->~paramType();                                           \
+      return result;                                                        \
+    }                                                                       \
+  };
+
+IMPL_PARAMTRAITS_BY_SERDE(LengthPercentage)
+IMPL_PARAMTRAITS_BY_SERDE(StyleOffsetPath)
+IMPL_PARAMTRAITS_BY_SERDE(StyleOffsetRotate)
+IMPL_PARAMTRAITS_BY_SERDE(StylePositionOrAuto)
+IMPL_PARAMTRAITS_BY_SERDE(StyleOffsetPosition)
+IMPL_PARAMTRAITS_BY_SERDE(StyleRotate)
+IMPL_PARAMTRAITS_BY_SERDE(StyleScale)
+IMPL_PARAMTRAITS_BY_SERDE(StyleTranslate)
+IMPL_PARAMTRAITS_BY_SERDE(StyleTransform)
+IMPL_PARAMTRAITS_BY_SERDE(StyleComputedTimingFunction)
+
+} /* namespace IPC */
+
+#endif /* mozilla_layers_LayersMessageUtils */
diff --git a/gfx/layers/ipc/LayersMessages.ipdlh b/gfx/layers/ipc/LayersMessages.ipdlh
new file mode 100644
index 0000000000..a0e4173507
--- /dev/null
+++ b/gfx/layers/ipc/LayersMessages.ipdlh
@@ -0,0 +1,373 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include protocol PCompositorBridge;
+include protocol PTexture;
+
+include "gfxipc/ShadowLayerUtils.h";
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+
+using mozilla::gfx::Glyph from "mozilla/gfx/2D.h";
+using mozilla::gfx::SamplingFilter from "mozilla/gfx/2D.h";
+using struct mozilla::gfx::DeviceColor from "mozilla/gfx/2D.h";
+using mozilla::gfx::Point from "mozilla/gfx/Point.h";
+using mozilla::gfx::Point3D from "mozilla/gfx/Point.h";
+using mozilla::gfx::IntPoint from "mozilla/gfx/Point.h";
+using mozilla::gfx::Matrix4x4 from "mozilla/gfx/Matrix.h";
+using mozilla::SideBits from "mozilla/gfx/Types.h";
+using nscolor from "nsColor.h";
+using nscoord from "nsCoord.h";
+using struct nsRect from "nsRect.h";
+using struct nsPoint from "nsPoint.h";
+using mozilla::TimeDuration from "mozilla/TimeStamp.h";
+using class mozilla::TimeStamp from "mozilla/TimeStamp.h";
+using mozilla::ScreenRotation from "mozilla/WidgetUtils.h";
+using nsCSSPropertyID from "nsCSSPropertyID.h";
+using mozilla::hal::ScreenOrientation from "mozilla/HalIPCUtils.h";
+using struct mozilla::layers::TextureInfo from "mozilla/layers/CompositorTypes.h";
+using mozilla::CSSCoord from "Units.h";
+using mozilla::CSSPoint from "Units.h";
+using mozilla::CSSRect from "Units.h";
+using mozilla::gfx::IntSize from "mozilla/gfx/2D.h";
+using mozilla::LayerMargin from "Units.h";
+using mozilla::LayerPoint from "Units.h";
+using mozilla::LayerCoord from "Units.h";
+using mozilla::LayerSize from "Units.h";
+using mozilla::LayerRect from "Units.h";
+using mozilla::LayerIntSize from "Units.h";
+using mozilla::LayerIntRect from "Units.h";
+using mozilla::LayerIntRegion from "Units.h";
+using mozilla::layers::TextureFlags from "mozilla/layers/CompositorTypes.h";
+using mozilla::ParentLayerIntRect from "Units.h";
+using mozilla::ParentLayerRect from "Units.h";
+using mozilla::LayoutDeviceIntRect from "Units.h";
+using mozilla::LayoutDevicePoint from "Units.h";
+using mozilla::LayoutDeviceRect from "Units.h";
+using mozilla::layers::ScaleMode from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::EventRegionsOverride from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::DiagnosticTypes from "mozilla/layers/CompositorTypes.h";
+using mozilla::layers::ScrollableLayerGuid::ViewID from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::ScrollDirection from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::LayersBackend from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::LayerHandle from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::CompositableHandle from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::CompositionPayload from "mozilla/layers/LayersTypes.h";
+[MoveOnly] using mozilla::CrossProcessSemaphoreHandle from "mozilla/ipc/CrossProcessSemaphore.h";
+using struct mozilla::void_t from "mozilla/ipc/IPCCore.h";
+using mozilla::layers::LayersId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::RemoteTextureId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::RemoteTextureOwnerId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::TransactionId from "mozilla/layers/LayersTypes.h";
+using mozilla::LengthPercentage from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleOffsetPath from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleOffsetRotate from "mozilla/ServoStyleConsts.h";
+using mozilla::StylePositionOrAuto from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleOffsetPosition from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleRotate from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleScale from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleTranslate from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleTransform from "mozilla/ServoStyleConsts.h";
+using mozilla::StyleComputedTimingFunction from "mozilla/ServoStyleConsts.h";
+
+namespace mozilla {
+namespace layers {
+
+struct TargetConfig {
+  IntRect naturalBounds;
+  ScreenRotation rotation;
+  ScreenOrientation orientation;
+  nsIntRegion clearRegion;
+};
+
+struct OpAttachCompositable {
+  LayerHandle layer;
+  CompositableHandle compositable;
+};
+
+struct OpAttachAsyncCompositable {
+  LayerHandle layer;
+  CompositableHandle compositable;
+};
+struct LayerColor { DeviceColor value; };
+
+[Comparable] union Animatable {
+  null_t;
+  float;
+  nscolor;
+  StyleRotate;
+  StyleScale;
+  StyleTranslate;
+  StyleTransform;
+  StyleOffsetPath;
+  LengthPercentage;
+  StyleOffsetRotate;
+  StylePositionOrAuto;
+  StyleOffsetPosition;
+};
+
+struct AnimationSegment {
+  Animatable startState;
+  Animatable endState;
+  float startPortion;
+  float endPortion;
+  uint8_t startComposite;
+  uint8_t endComposite;
+  StyleComputedTimingFunction? sampleFn;
+};
+
+[Comparable] struct MotionPathData {
+  // The transform-origin property for motion in css pixels
+  CSSPoint origin;
+  // The adjustment for the anchor point of motion path.
+  CSSPoint anchorAdjustment;
+  // The coord box of the containing block.
+  nsRect coordBox;
+  // The current position of this transfromed box in the coordinate system of
+  // its containing block.
+  nsPoint currentPosition;
+  // The reference length for computing ray(contain) (in css pixels).
+  CSSCoord rayContainReferenceLength;
+  // The resolved border-radius of its containing block. If the array size is
+  // zero, we don't have radius.
+  nscoord[] coordBoxInsetRadii;
+};
+
+[Comparable] struct PartialPrerenderData {
+  LayoutDeviceRect rect;
+  SideBits overflowedSides;
+  // the scroll id of the nearest scrollable frame of this partial prerender
+  // data.
+  ViewID scrollId;
+  // The clip rectangle of the nearest scrollable frame.
+  // NOTE: This should be used only for fallback cases where APZ is not enabled.
+  ParentLayerRect clipRect;
+  // a transform from the coordinate space of the animated element to a
+  // coordinate space where the `clipRect` can be applied.
+  Matrix4x4 transformInClip; // Used only for WebRender.
+  // the position relative to the reference frame of the animated transform
+  // element in the element coordinate space.
+  LayoutDevicePoint position; // Used only for WebRender.
+};
+
+// Transforms need extra information to correctly convert the list of transform
+// functions to a Matrix4x4 that can be applied directly to the layer.
+[Comparable] struct TransformData {
+  // the origin of the frame being transformed in app units
+  nsPoint origin;
+  // the transform-origin property for the transform in device pixels
+  Point3D transformOrigin;
+  nsRect bounds;
+  int32_t appUnitsPerDevPixel;
+  MotionPathData? motionPathData;
+  PartialPrerenderData? partialPrerenderData;
+};
+
+// The scroll timeline information.
+struct ScrollTimelineOptions {
+  // The source of the scroll-timeline.
+  ViewID source;
+  // The physical direction.
+  ScrollDirection axis;
+};
+
+struct Animation {
+  // The zero time of this Animation's timeline. May be null if isNotPlaying is
+  // true.
+  TimeStamp originTime;
+  // The start time is relative to the originTime. This allows us to represent
+  // start times in the distant past that cannot be expressed using a TimeStamp.
+  TimeDuration? startTime;
+  TimeDuration delay;
+  TimeDuration endDelay;
+  // The value of the animation's current time at the moment it was sent to the
+  // compositor.  This value will be used for below cases:
+  // 1) Animations that are play-pending. Initially these animations will have a
+  //    null |startTime|. Once the animation is ready to start (i.e. painting
+  //    has finished), we calculate an appropriate value of |startTime| such
+  //    that playback begins from |holdTime|.
+  // 2) Not playing animations (e.g. paused and finished animations). In this
+  //   case the |holdTime| represents the current time the animation will
+  //   maintain.
+  TimeDuration holdTime;
+  TimeDuration duration;
+  // For each frame, the interpolation point is computed based on the
+  // startTime, the direction, the duration, and the current time.
+  // The segments must uniquely cover the portion from 0.0 to 1.0
+  AnimationSegment[] segments;
+  // Number of times to repeat the animation, including positive infinity.
+  // Values <= 0 mean the animation will not play (although events are still
+  // dispatched on the main thread).
+  float iterations;
+  float iterationStart;
+  // This uses the NS_STYLE_ANIMATION_DIRECTION_* constants.
+  uint8_t direction;
+  // This uses dom::FillMode.
+  uint8_t fillMode;
+  nsCSSPropertyID property;
+  float playbackRate;
+  // When performing an asynchronous update to the playbackRate, |playbackRate|
+  // above is the updated playbackRate while |previousPlaybackRate| is the
+  // existing playbackRate. This is used by AnimationInfo to update the
+  // startTime based on the 'readyTime' (timestamp at the end of painting)
+  // and is not used beyond that point.
+  //
+  // It is set to numeric_limits<float>::quiet_NaN() when no asynchronous update
+  // to the playbackRate is being performed.
+  float previousPlaybackRate;
+  // This is used in the transformed progress calculation.
+  StyleComputedTimingFunction? easingFunction;
+  uint8_t iterationComposite;
+  // True if the animation has a fixed current time (e.g. paused and
+  // forward-filling animations).
+  bool isNotPlaying;
+  // True if this is not an animating property. For some transform-like
+  // properties, we just send their baseStyles for merging with other animating
+  // properties. In this case, we don't have animation information on this
+  // property, and so don't need to do interpolation.
+  bool isNotAnimating;
+  // The base style that animations should composite with. This is only set for
+  // 1. scroll animations with positive delays, or
+  // 2. animations with a composite mode of additive or accumulate, and only for
+  //    the first animation in the set (i.e. the animation that is lowest in the
+  //    stack).
+  // In all other cases the value is null_t.
+  Animatable baseStyle;
+  // An optional data specific for transform like properies.
+  TransformData? transformData;
+  // If this is present, the animation is driven by a ScrollTimeline, and
+  // this structure contains information about that timeline.
+  ScrollTimelineOptions? scrollTimelineOptions;
+};
+
+struct CompositorAnimations {
+  Animation[] animations;
+  // This id is used to map the layer animations between content
+  // and compositor side
+  uint64_t id;
+};
+
+struct ShmemSection {
+  Shmem shmem;
+  uint32_t offset;
+  uint32_t size;
+};
+
+struct CrossProcessSemaphoreDescriptor {
+  CrossProcessSemaphoreHandle sem;
+};
+
+union ReadLockDescriptor {
+  ShmemSection;
+  CrossProcessSemaphoreDescriptor;
+  uintptr_t;
+  null_t;
+};
+
+/**
+ * Tells the CompositableHost to remove the corresponding TextureHost
+ */
+struct OpRemoveTexture {
+  PTexture texture;
+};
+
+struct TimedTexture {
+  PTexture texture;
+  TimeStamp timeStamp;
+  IntRect picture;
+  uint32_t frameID;
+  uint32_t producerID;
+  bool readLocked;
+};
+
+/**
+ * Tells the compositor-side which textures to use (for example, as front buffer
+ * if there are several textures for double buffering).
+ * This provides a list of textures with timestamps, ordered by timestamp.
+ * The newest texture whose timestamp is <= the current time is rendered
+ * (where null is considered less than every other timestamp). If there is no
+ * such texture, the first texture is rendered.
+ * The first timestamp value can be null, but the others must not be.
+ * The list must not be empty.
+ */
+struct OpUseTexture {
+  TimedTexture[] textures;
+};
+
+struct OpUseRemoteTexture {
+  RemoteTextureId textureId;
+  RemoteTextureOwnerId ownerId;
+  IntSize size;
+  TextureFlags textureFlags;
+};
+
+struct OpEnableRemoteTexturePushCallback {
+  RemoteTextureOwnerId ownerId;
+  IntSize size;
+  TextureFlags textureFlags;
+};
+
+struct OpNotifyNotUsed {
+  uint64_t TextureId;
+  uint64_t fwdTransactionId;
+};
+
+union CompositableOperationDetail {
+  OpRemoveTexture;
+
+  OpUseTexture;
+
+  OpUseRemoteTexture;
+
+  OpEnableRemoteTexturePushCallback;
+};
+
+struct CompositableOperation {
+  CompositableHandle compositable;
+  CompositableOperationDetail detail;
+};
+
+// Operations related to destroying resources, always handled after the other
+// operations for safety.
+union OpDestroy {
+  PTexture;
+  CompositableHandle;
+};
+
+// Replies to operations
+
+struct OpContentBufferSwap {
+  CompositableHandle compositable;
+  nsIntRegion frontUpdatedRegion;
+};
+
+/**
+ * An ImageCompositeNotification is sent the first time a particular
+ * image is composited by an ImageHost.
+ */
+struct ImageCompositeNotification {
+  CompositableHandle compositable;
+  TimeStamp imageTimeStamp;
+  TimeStamp firstCompositeTimeStamp;
+  uint32_t frameID;
+  uint32_t producerID;
+};
+
+union AsyncParentMessageData {
+  OpNotifyNotUsed;
+};
+
+union OMTAValue {
+  null_t;
+  nscolor;
+  float;
+  Matrix4x4;
+};
+
+} // namespace
+} // namespace
diff --git a/gfx/layers/ipc/LayersSurfaces.ipdlh b/gfx/layers/ipc/LayersSurfaces.ipdlh
new file mode 100644
index 0000000000..e38b2c74dc
--- /dev/null
+++ b/gfx/layers/ipc/LayersSurfaces.ipdlh
@@ -0,0 +1,217 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include "gfxipc/ShadowLayerUtils.h";
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+
+using gfxPoint from "gfxPoint.h";
+using nsIntRegion from "nsRegion.h";
+using mozilla::StereoMode from "ImageTypes.h";
+using struct mozilla::null_t from "mozilla/ipc/IPCCore.h";
+using mozilla::WindowsHandle from "mozilla/ipc/IPCTypes.h";
+using mozilla::gfx::YUVColorSpace from "mozilla/gfx/Types.h";
+using mozilla::gfx::ChromaSubsampling from "mozilla/gfx/Types.h";
+using mozilla::gfx::ColorDepth from "mozilla/gfx/Types.h";
+using mozilla::gfx::ColorRange from "mozilla/gfx/Types.h";
+using mozilla::gfx::ColorSpace2 from "mozilla/gfx/Types.h";
+using mozilla::gfx::SurfaceFormat from "mozilla/gfx/Types.h";
+using mozilla::gfx::IntRect from "mozilla/gfx/Rect.h";
+using mozilla::gfx::IntSize from "mozilla/gfx/Point.h";
+using mozilla::gfx::Matrix4x4 from "mozilla/gfx/Matrix.h";
+using mozilla::gfx::FenceInfo from "mozilla/gfx/FileHandleWrapper.h";
+[RefCounted] using mozilla::gfx::FileHandleWrapper from "mozilla/gfx/FileHandleWrapper.h";
+[MoveOnly] using mozilla::ipc::SharedMemoryBasic::Handle from "mozilla/ipc/SharedMemoryBasic.h";
+using gfxImageFormat from "gfxTypes.h";
+using mozilla::layers::MaybeVideoBridgeSource from "mozilla/layers/VideoBridgeUtils.h";
+using mozilla::layers::RemoteTextureId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::RemoteTextureOwnerId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::GpuProcessTextureId from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::GpuProcessQueryId from "mozilla/layers/LayersTypes.h";
+using mozilla::wr::ExternalImageSource from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::ExternalImageId from "mozilla/webrender/WebRenderTypes.h";
+
+namespace mozilla {
+namespace layers {
+
+[Comparable] struct SurfaceDescriptorD3D10 {
+  nullable FileHandleWrapper handle;
+  GpuProcessTextureId? gpuProcessTextureId;
+  uint32_t arrayIndex;
+  SurfaceFormat format;
+  IntSize size;
+  ColorSpace2 colorSpace;
+  ColorRange colorRange;
+  bool hasKeyedMutex;
+  FenceInfo? fenceInfo;
+  GpuProcessQueryId? gpuProcessQueryId;
+};
+
+[Comparable] struct SurfaceDescriptorDXGIYCbCr {
+  nullable FileHandleWrapper handleY;
+  nullable FileHandleWrapper handleCb;
+  nullable FileHandleWrapper handleCr;
+  IntSize size;
+  IntSize sizeY;
+  IntSize sizeCbCr;
+  ColorDepth colorDepth;
+  YUVColorSpace yUVColorSpace;
+  ColorRange colorRange;
+};
+
+[Comparable] struct SurfaceDescriptorMacIOSurface {
+  uint32_t surfaceId;
+  bool isOpaque;
+  YUVColorSpace yUVColorSpace;
+};
+
+[Comparable] struct SurfaceDescriptorDMABuf {
+  uint32_t bufferType;
+  uint64_t[] modifier;
+  uint32_t flags;
+  FileDescriptor[] fds;
+  uint32_t[] width;
+  uint32_t[] height;
+  uint32_t[] widthAligned;
+  uint32_t[] heightAligned;
+  uint32_t[] format;
+  uint32_t[] strides;
+  uint32_t[] offsets;
+  YUVColorSpace yUVColorSpace;
+  ColorRange colorRange;
+  FileDescriptor[] fence;
+  uint32_t uid;
+  FileDescriptor[] refCount;
+};
+
+[Comparable] struct SurfaceTextureDescriptor {
+  uint64_t handle;
+  IntSize size;
+  SurfaceFormat format;
+  bool continuous;
+  bool forceBT709ColorSpace;
+  Matrix4x4? transformOverride;
+};
+
+[Comparable] struct SurfaceDescriptorAndroidHardwareBuffer {
+  uint64_t bufferId;
+  IntSize size;
+  SurfaceFormat format;
+};
+
+[Comparable] struct EGLImageDescriptor {
+  uintptr_t image; // `EGLImage` is a `void*`.
+  uintptr_t fence;
+  IntSize size;
+  bool hasAlpha;
+};
+
+[Comparable] struct SurfaceDescriptorSharedGLTexture {
+  uint32_t texture;
+  uint32_t target;
+  uintptr_t fence;
+  IntSize size;
+  bool hasAlpha;
+};
+
+[Comparable] struct SurfaceDescriptorDcompSurface {
+  FileDescriptor handle;
+  IntSize size;
+  SurfaceFormat format;
+};
+
+[Comparable] union RemoteDecoderVideoSubDescriptor {
+  SurfaceDescriptorD3D10;
+  SurfaceDescriptorDXGIYCbCr;
+  SurfaceDescriptorDMABuf;
+  SurfaceDescriptorMacIOSurface;
+  SurfaceDescriptorDcompSurface;
+  null_t;
+};
+
+[Comparable] struct SurfaceDescriptorRemoteDecoder {
+  uint64_t handle;
+  RemoteDecoderVideoSubDescriptor subdesc;
+  MaybeVideoBridgeSource source;
+};
+
+[Comparable] union SurfaceDescriptorGPUVideo {
+  SurfaceDescriptorRemoteDecoder;
+};
+
+[Comparable] struct RGBDescriptor {
+  IntSize size;
+  SurfaceFormat format;
+};
+
+[Comparable] struct YCbCrDescriptor {
+  IntRect display;
+  IntSize ySize;
+  uint32_t yStride;
+  IntSize cbCrSize;
+  uint32_t cbCrStride;
+  uint32_t yOffset;
+  uint32_t cbOffset;
+  uint32_t crOffset;
+  StereoMode stereoMode;
+  ColorDepth colorDepth;
+  YUVColorSpace yUVColorSpace;
+  ColorRange colorRange;
+  ChromaSubsampling chromaSubsampling;
+};
+
+[Comparable] union BufferDescriptor {
+  RGBDescriptor;
+  YCbCrDescriptor;
+};
+
+[Comparable] union MemoryOrShmem {
+  uintptr_t;
+  Shmem;
+};
+
+[Comparable] struct SurfaceDescriptorBuffer {
+  BufferDescriptor desc;
+  MemoryOrShmem data;
+};
+
+[Comparable] struct SurfaceDescriptorShared
+{
+  IntSize size;
+  int32_t stride;
+  SurfaceFormat format;
+  Handle handle;
+};
+
+[Comparable] struct SurfaceDescriptorExternalImage
+{
+  ExternalImageSource source;
+  ExternalImageId id;
+};
+
+[Comparable] struct SurfaceDescriptorRemoteTexture {
+  RemoteTextureId textureId;
+  RemoteTextureOwnerId ownerId;
+};
+
+[Comparable] union SurfaceDescriptor {
+  SurfaceDescriptorBuffer;
+  SurfaceDescriptorD3D10;
+  SurfaceDescriptorDXGIYCbCr;
+  SurfaceDescriptorDMABuf;
+  SurfaceTextureDescriptor;
+  SurfaceDescriptorAndroidHardwareBuffer;
+  EGLImageDescriptor;
+  SurfaceDescriptorMacIOSurface;
+  SurfaceDescriptorSharedGLTexture;
+  SurfaceDescriptorGPUVideo;
+  SurfaceDescriptorRemoteTexture;
+  SurfaceDescriptorDcompSurface;
+  SurfaceDescriptorExternalImage;
+  null_t;
+};
+
+} // namespace
+} // namespace
diff --git a/gfx/layers/ipc/PAPZ.ipdl b/gfx/layers/ipc/PAPZ.ipdl
new file mode 100644
index 0000000000..5525a25edd
--- /dev/null
+++ b/gfx/layers/ipc/PAPZ.ipdl
@@ -0,0 +1,81 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/RemoteContentController.h";
+
+include protocol PCompositorBridge;
+
+using mozilla::CSSRect from "Units.h";
+using struct mozilla::layers::RepaintRequest from "mozilla/layers/RepaintRequest.h";
+using struct mozilla::layers::ScrollableLayerGuid from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::ScrollableLayerGuid::ViewID from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::GeckoContentController_APZStateChange from "mozilla/layers/GeckoContentControllerTypes.h";
+using mozilla::layers::ScrollDirection from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::MatrixMessage from "mozilla/layers/MatrixMessage.h";
+using mozilla::dom::TabId from "mozilla/dom/ipc/IdType.h";
+using mozilla::dom::ContentParentId from "mozilla/dom/ipc/IdType.h";
+using mozilla::layers::AsyncDragMetrics from "mozilla/layers/AsyncDragMetrics.h";
+using class nsRegion from "nsRegion.h";
+
+namespace mozilla {
+namespace layers {
+
+
+/**
+ * PAPZ is a protocol for remoting a GeckoContentController. PAPZ lives on the
+ * PCompositorBridge protocol which either connects to the compositor thread
+ * in the main process, or to the compositor thread in the gpu processs.
+ *
+ * PAPZParent lives in the compositor thread, while PAPZChild lives wherever the remoted
+ * GeckoContentController lives (generally the main thread of the main or content process).
+ * RemoteContentController implements PAPZParent, while APZChild implements PAPZChild.
+ *
+ * PAPZ is always used for ContentProcessController and only used for ChromeProcessController
+ * when there is a gpu process, otherwhise ChromeProcessController is used directly on the
+ * compositor thread. Only the methods that are used by the [Chrome,Content]ProcessController
+ * are implemented. If a new method is needed then PAPZ, APZChild, and RemoteContentController
+ * must be updated to handle it.
+ */
+[ManualDealloc, ParentImpl="RemoteContentController"]
+sync protocol PAPZ
+{
+  manager PCompositorBridge;
+
+parent:
+  async __delete__();
+
+child:
+  async LayerTransforms(MatrixMessage[] aTransforms);
+
+  [Priority=control]
+  async RequestContentRepaint(RepaintRequest request);
+
+  async UpdateOverscrollVelocity(ScrollableLayerGuid aGuid, float aX, float aY, bool aIsRootContent);
+
+  async UpdateOverscrollOffset(ScrollableLayerGuid aGuid, float aX, float aY, bool aIsRootContent);
+
+  async NotifyMozMouseScrollEvent(ViewID aScrollId, nsString aEvent);
+
+  async NotifyAPZStateChange(ScrollableLayerGuid aGuid, GeckoContentController_APZStateChange aChange, int aArg, uint64_t? aInputBlockId);
+
+  [Priority=control]
+  async NotifyFlushComplete();
+
+  async NotifyAsyncScrollbarDragInitiated(uint64_t aDragBlockId, ViewID aScrollId, ScrollDirection aDirection);
+
+  async NotifyAsyncScrollbarDragRejected(ViewID aScrollId);
+
+  async NotifyAsyncAutoscrollRejected(ViewID aScrollId);
+
+both:
+  async Destroy();
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PAPZCTreeManager.ipdl b/gfx/layers/ipc/PAPZCTreeManager.ipdl
new file mode 100644
index 0000000000..a08e2cfeb1
--- /dev/null
+++ b/gfx/layers/ipc/PAPZCTreeManager.ipdl
@@ -0,0 +1,97 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "ipc/nsGUIEventIPC.h";
+
+include protocol PCompositorBridge;
+
+using mozilla::CSSRect from "Units.h";
+using mozilla::LayoutDeviceCoord from "Units.h";
+using mozilla::LayoutDevicePoint from "Units.h";
+using mozilla::ScreenPoint from "Units.h";
+using mozilla::layers::ZoomTarget from "mozilla/layers/DoubleTapToZoom.h";
+using mozilla::layers::DoubleTapToZoomMetrics from "mozilla/layers/DoubleTapToZoom.h";
+using mozilla::layers::ZoomConstraints from "mozilla/layers/ZoomConstraints.h";
+using mozilla::layers::ScrollableLayerGuid from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::ScrollableLayerGuid::ViewID from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::TouchBehaviorFlags from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::AsyncDragMetrics from "mozilla/layers/AsyncDragMetrics.h";
+using mozilla::layers::GeckoContentController_TapType from "mozilla/layers/GeckoContentControllerTypes.h";
+using mozilla::layers::APZHandledResult from "mozilla/layers/APZInputBridge.h";
+using mozilla::layers::BrowserGestureResponse from "mozilla/layers/APZInputBridge.h";
+using class mozilla::layers::KeyboardMap from "mozilla/layers/KeyboardMap.h";
+using mozilla::wr::RenderRoot from "mozilla/webrender/WebRenderTypes.h";
+
+using mozilla::Modifiers from "mozilla/EventForwards.h";
+using mozilla::PinchGestureInput::PinchGestureType from "InputData.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * PAPZCTreeManager is a protocol for remoting an IAPZCTreeManager. PAPZCTreeManager
+ * lives on the PCompositorBridge protocol which either connects to the compositor
+ * thread in the main process, or to the compositor thread in the gpu processs.
+ *
+ * PAPZCTreeManagerParent lives in the compositor thread, while PAPZCTreeManagerChild
+ * lives in the main thread of the main or the content process. APZCTreeManagerParent
+ * and APZCTreeManagerChild implement this protocol.
+ */
+[ManualDealloc]
+protocol PAPZCTreeManager
+{
+manager PCompositorBridge;
+
+parent:
+
+  // These messages correspond to the methods
+  // on the IAPZCTreeManager interface
+
+  async ZoomToRect(ScrollableLayerGuid aGuid, ZoomTarget aZoomTarget, uint32_t Flags);
+
+  async ContentReceivedInputBlock(uint64_t aInputBlockId, bool PreventDefault);
+
+  async SetTargetAPZC(uint64_t aInputBlockId, ScrollableLayerGuid[] Targets);
+
+  async UpdateZoomConstraints(ScrollableLayerGuid aGuid, ZoomConstraints? aConstraints);
+
+  async SetKeyboardMap(KeyboardMap aKeyboardMap);
+
+  async SetDPI(float aDpiValue);
+
+  async SetAllowedTouchBehavior(uint64_t aInputBlockId, TouchBehaviorFlags[] aValues);
+
+  async StartScrollbarDrag(ScrollableLayerGuid aGuid, AsyncDragMetrics aDragMetrics);
+
+  async StartAutoscroll(ScrollableLayerGuid aGuid, ScreenPoint aAnchorLocation);
+
+  async StopAutoscroll(ScrollableLayerGuid aGuid);
+
+  async SetLongTapEnabled(bool aTapGestureEnabled);
+
+  async SetBrowserGestureResponse(uint64_t aInputBlockId,
+                                  BrowserGestureResponse aResponse);
+
+  async __delete__();
+
+child:
+
+  async HandleTap(GeckoContentController_TapType aType, LayoutDevicePoint point, Modifiers aModifiers,
+                  ScrollableLayerGuid aGuid, uint64_t aInputBlockId,
+                  DoubleTapToZoomMetrics? aDoubleTapToZoomMetrics);
+
+  async NotifyPinchGesture(PinchGestureType aType, ScrollableLayerGuid aGuid,
+                           LayoutDevicePoint aFocusPoint, LayoutDeviceCoord aSpanChange,
+                           Modifiers aModifiers);
+
+  async CancelAutoscroll(ViewID aScrollId);
+
+  async NotifyScaleGestureComplete(ViewID aScrollId, float aScale);
+};
+
+} // namespace gfx
+} // namespace mozilla
diff --git a/gfx/layers/ipc/PAPZInputBridge.ipdl b/gfx/layers/ipc/PAPZInputBridge.ipdl
new file mode 100644
index 0000000000..7564757b28
--- /dev/null
+++ b/gfx/layers/ipc/PAPZInputBridge.ipdl
@@ -0,0 +1,88 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include "ipc/nsGUIEventIPC.h";
+
+using mozilla::LayoutDeviceIntPoint from "Units.h";
+using struct mozilla::layers::ScrollableLayerGuid from "mozilla/layers/ScrollableLayerGuid.h";
+using struct mozilla::layers::APZEventResult from "mozilla/layers/APZInputBridge.h";
+using struct mozilla::layers::APZHandledResult from "mozilla/layers/APZInputBridge.h";
+
+using mozilla::EventMessage from "mozilla/EventForwards.h";
+using class mozilla::MultiTouchInput from "InputData.h";
+using class mozilla::MouseInput from "InputData.h";
+using class mozilla::PanGestureInput from "InputData.h";
+using class mozilla::PinchGestureInput from "InputData.h";
+using class mozilla::TapGestureInput from "InputData.h";
+using class mozilla::ScrollWheelInput from "InputData.h";
+using class mozilla::KeyboardInput from "InputData.h";
+
+using mozilla::layers::LayersId from "mozilla/layers/LayersTypes.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * This protocol is used to send input events from the UI process to the
+ * GPU process for handling by APZ. There is one instance per top-level
+ * compositor, or in other words, one instance per concrete APZCTreeManager
+ * instance. The child side lives on the controller thread in the UI process,
+ * ie the main thread on most platforms, but the Android UI thread on Android.
+ * The parent side lives on the main thread in the GPU process. If there is no
+ * GPU process, then this protocol is not instantiated.
+ */
+[ParentProc=GPU, ChildProc=Parent]
+sync protocol PAPZInputBridge
+{
+parent:
+  // The following messages are used to
+  // implement the ReceiveInputEvent methods
+
+  sync ReceiveMultiTouchInputEvent(MultiTouchInput aEvent, bool aWantsCallback)
+      returns(APZEventResult aOutResult, MultiTouchInput aOutEvent);
+
+  sync ReceiveMouseInputEvent(MouseInput aEvent, bool aWantsCallback)
+    returns (APZEventResult aOutResult,
+             MouseInput     aOutEvent);
+
+  sync ReceivePanGestureInputEvent(PanGestureInput aEvent, bool aWantsCallback)
+    returns (APZEventResult  aOutResult,
+             PanGestureInput aOutEvent);
+
+  sync ReceivePinchGestureInputEvent(PinchGestureInput aEvent,
+                                     bool aWantsCallback)
+    returns (APZEventResult    aOutResult,
+             PinchGestureInput aOutEvent);
+
+  sync ReceiveTapGestureInputEvent(TapGestureInput aEvent, bool aWantsCallback)
+    returns (APZEventResult  aOutResult,
+             TapGestureInput aOutEvent);
+
+  sync ReceiveScrollWheelInputEvent(ScrollWheelInput aEvent,
+                                    bool aWantsCallback)
+    returns (APZEventResult   aOutResult,
+             ScrollWheelInput aOutEvent);
+
+  sync ReceiveKeyboardInputEvent(KeyboardInput aEvent, bool aWantsCallback)
+    returns (APZEventResult aOutResult,
+             KeyboardInput  aOutEvent);
+
+  async UpdateWheelTransaction(LayoutDeviceIntPoint aRefPoint,
+                               EventMessage aEventMessage,
+                               ScrollableLayerGuid? aTargetGuid);
+
+  sync ProcessUnhandledEvent(LayoutDeviceIntPoint aRefPoint)
+    returns (LayoutDeviceIntPoint   aOutRefPoint,
+             ScrollableLayerGuid    aOutTargetGuid,
+             uint64_t               aOutFocusSequenceNumber,
+             LayersId               aOutLayersId);
+
+child:
+  async CallInputBlockCallback(uint64_t aInputBlockId,
+                               APZHandledResult aHandledResult);
+};
+
+} // namespace gfx
+} // namespace mozilla
diff --git a/gfx/layers/ipc/PCanvas.ipdl b/gfx/layers/ipc/PCanvas.ipdl
new file mode 100644
index 0000000000..5187e61d23
--- /dev/null
+++ b/gfx/layers/ipc/PCanvas.ipdl
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et : */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PCanvasManager;
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/CanvasTranslator.h";
+
+[MoveOnly] using mozilla::CrossProcessSemaphoreHandle from "mozilla/ipc/CrossProcessSemaphore.h";
+using mozilla::layers::TextureType from "mozilla/layers/LayersTypes.h";
+[MoveOnly] using mozilla::ipc::SharedMemoryBasic::Handle from "mozilla/ipc/SharedMemoryBasic.h";
+using mozilla::gfx::BackendType from "mozilla/gfx/Types.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * PCanvas is the IPDL for recorded Canvas drawing.
+ */
+[ParentImpl="CanvasTranslator"]
+async protocol PCanvas {
+  manager PCanvasManager;
+
+parent:
+  /**
+   * Initialize a CanvasTranslator for a particular TextureType, which
+   * translates events from shared memory buffers. aHeaderHandle is a shared
+   * memory handle for the control header. aBufferHandles are shared memory
+   * handles for the initial buffers for translation. aBufferSize is the size of
+   * each aBufferHandles' memory and the default size. aReaderSem and aWriterSem
+   * are handles for the semaphores to handle waiting on either side.
+   */
+  async InitTranslator(TextureType aTextureType, BackendType aBackendType,
+                       Handle aHeaderHandle, Handle[] aBufferHandles,
+                       uint64_t aBufferSize,
+                       CrossProcessSemaphoreHandle aReaderSem,
+                       CrossProcessSemaphoreHandle aWriterSem);
+
+  /**
+   * Restart the translation from a Stopped state.
+   */
+  async RestartTranslation();
+
+  /**
+   * Adds a new buffer to be translated. The current buffer will be recycled if
+   * it is of the default size. The translation will then be restarted.
+   */
+  async AddBuffer(Handle aBufferHandle, uint64_t aBufferSize);
+
+  /**
+   * Sets the shared memory to be used for readback.
+   */
+  async SetDataSurfaceBuffer(Handle aBufferHandle, uint64_t aBufferSize);
+
+  /**
+   * Notify CanvasTranslator it is about to be minimized.
+   */
+  async ClearCachedResources();
+
+  async __delete__();
+
+child:
+  /**
+   * Notify that the canvas device used by the translator has changed.
+   */
+  async NotifyDeviceChanged();
+
+  /**
+   * Deactivate remote canvas, which will cause fall back to software.
+   */
+  async Deactivate();
+
+  /**
+   * Block further accelerated canvases from being created, but allow existing
+   * canvases to continue processing.
+   */
+  async BlockCanvas();
+
+  /**
+   * Notify that a remote accelerated canvas requires a fallback refresh.
+   */
+  async NotifyRequiresRefresh(int64_t aTextureId);
+
+  /**
+   * Cache the shmem of the framebuffer for snapshotting.
+   */
+  async SnapshotShmem(int64_t aTextureId, Handle aShmemHandle, uint32_t aShmemSize) returns (bool aSuccess);
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PCompositorBridge.ipdl b/gfx/layers/ipc/PCompositorBridge.ipdl
new file mode 100644
index 0000000000..abe89fb87d
--- /dev/null
+++ b/gfx/layers/ipc/PCompositorBridge.ipdl
@@ -0,0 +1,209 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include LayersMessages;
+include PlatformWidgetTypes;
+include PCompositorBridgeTypes;
+include protocol PAPZ;
+include protocol PAPZCTreeManager;
+include protocol PBrowser;
+include protocol PCompositorManager;
+include protocol PCompositorWidget;
+include protocol PTexture;
+include protocol PWebRenderBridge;
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+include "mozilla/layers/CompositorBridgeParent.h";
+
+using struct mozilla::null_t from "mozilla/ipc/IPCCore.h";
+using struct mozilla::layers::LayersId from "mozilla/layers/LayersTypes.h";
+using struct mozilla::layers::TextureFactoryIdentifier from "mozilla/layers/CompositorTypes.h";
+using struct mozilla::layers::ScrollableLayerGuid from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::ScrollableLayerGuid::ViewID from "mozilla/layers/ScrollableLayerGuid.h";
+using mozilla::layers::WindowKind from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::LayersBackend from "mozilla/layers/LayersTypes.h";
+using mozilla::CSSIntRegion from "Units.h";
+using mozilla::LayoutDeviceIntPoint from "Units.h";
+using mozilla::LayoutDeviceIntRegion from "Units.h";
+using mozilla::LayoutDeviceIntSize from "Units.h";
+using class mozilla::TimeStamp from "mozilla/TimeStamp.h";
+using mozilla::layers::TextureFlags from "mozilla/layers/CompositorTypes.h";
+using mozilla::layers::CompositorOptions from "mozilla/layers/CompositorOptions.h";
+using mozilla::wr::PipelineId from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::IdNamespace from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::RenderReasons from "mozilla/webrender/webrender_ffi.h";
+using base::ProcessId from "base/process.h";
+using mozilla::wr::MaybeExternalImageId from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::layers::TransactionId from "mozilla/layers/LayersTypes.h";
+
+namespace mozilla {
+namespace layers {
+
+struct FrameStats {
+  TransactionId id;
+  TimeStamp compositeStart;
+  TimeStamp renderStart;
+  TimeStamp compositeEnd;
+  int32_t contentFrameTime;
+  double resourceUploadTime;
+  double gpuCacheUploadTime;
+  TimeStamp transactionStart;
+  TimeStamp refreshStart;
+  TimeStamp fwdTime;
+  TimeStamp sceneBuiltTime;
+  uint32_t skippedComposites;
+  nsCString url;
+};
+
+/**
+ * The PCompositorBridge protocol is a top-level protocol for the compositor.
+ * There is an instance of the protocol for each compositor, plus one for each
+ * content process. In other words:
+ * - There is a CompositorBridgeParent/CompositorBridgeChild pair created
+ *   for each "top level browser window", which has its own compositor. The
+ *   CompositorBridgeChild instance lives in the UI process, and the
+ *   CompositorBridgeParent lives in the GPU process (if there is one) or the
+ *   UI process otherwise.
+ * - There is also a ContentCompositorBridgeParent/CompositorBridgeChild
+ *   pair created for each content process. The ContentCompositorBridgeParent
+ *   lives in the GPU process (if there is one) or the UI process otherwise. The
+ *   CompositorBridgeChild is a singleton in the content process. Note that
+ *   a given content process may have multiple browser instances (represented
+ *   by BrowserChild instances), that are attached to different windows, and therefore
+ *   rendered by different compositors. This means that when a browser instance
+ *   sends messages via its CompositorBridgeChild, the corresponding
+ *   ContentCompositorBridgeParent has to use the layers id in the message
+ *   to find the correct compositor or CompositorBridgeParent to pass the message
+ *   on to.
+ *
+ * One of the main goals of this protocol is to manage the PLayerTransaction sub-
+ * protocol, which is per-browser. A lot of the functions in the protocol are
+ * basically multiplexing/demultiplexing stuff in PLayerTransaction.
+ */
+[ParentImpl="CompositorBridgeParentBase"]
+sync protocol PCompositorBridge
+{
+  manager PCompositorManager;
+
+  manages PAPZ;
+  manages PAPZCTreeManager;
+  // A Compositor manages a single Layer Manager (PLayerTransaction)
+  manages PTexture;
+  manages PCompositorWidget;
+  manages PWebRenderBridge;
+
+child:
+  // The compositor completed a layers transaction. id is the layers id
+  // of the child layer tree that was composited (or 0 when notifying
+  // the root layer tree).
+  // transactionId is the id of the transaction before this composite, or 0
+  // if there was no transaction since the last composite.
+  [Priority=control] async DidComposite(LayersId id,
+                                        TransactionId[] transactionId,
+                                        TimeStamp compositeStart,
+                                        TimeStamp compositeEnd);
+
+  async NotifyFrameStats(FrameStats[] aFrameStats);
+
+  async ParentAsyncMessages(AsyncParentMessageData[] aMessages);
+
+  async ObserveLayersUpdate(LayersId aLayersId, bool aActive);
+
+  async CompositorOptionsChanged(LayersId id, CompositorOptions newOptions);
+
+  async NotifyJankedAnimations(LayersId id, uint64_t[] aJankedAnimations);
+
+parent:
+  async __delete__();
+
+  // Must be called before Initialize().
+  async PCompositorWidget(CompositorWidgetInitData aInitData);
+
+  // When out-of-process, this must be called to finish initialization.
+  sync Initialize(LayersId rootLayerTreeId);
+
+  // Must be called after Initialize(), and only succeeds if AsyncPanZoomEnabled() is true.
+  async PAPZ(LayersId layersId);
+  async PAPZCTreeManager(LayersId layersId);
+
+  // The child is about to be destroyed, so perform any necessary cleanup.
+  sync WillClose();
+
+  // Pause/resume the compositor. These are intended to be used on mobile, when
+  // the compositor needs to pause/resume in lockstep with the application.
+  sync Pause();
+  sync Resume();
+  async ResumeAsync();
+
+  // See bug 1316632 comment #33 for why this has to be sync. Otherwise,
+  // there are ordering issues with SendPLayerTransactionConstructor.
+  sync NotifyChildCreated(LayersId id)
+    returns (CompositorOptions compositorOptions);
+
+  // This version of NotifyChildCreated also performs a layer tree mapping.
+  //
+  // See bug 1316632 comment #33 for why this has to be sync. Otherwise,
+  // there are ordering issues with SendPLayerTransactionConstructor.
+  sync MapAndNotifyChildCreated(LayersId id, ProcessId owner)
+    returns (CompositorOptions compositorOptions);
+
+  async AdoptChild(LayersId id);
+
+  // Same as NotifyChildCreated, but used when child processes need to
+  // reassociate layers. This must be synchronous to ensure that the
+  // association happens before PLayerTransactions are sent over the
+  // cross-process bridge.
+  sync NotifyChildRecreated(LayersId id)
+    returns (CompositorOptions compositorOptions);
+
+  async NotifyMemoryPressure();
+
+  // Make sure any pending composites are started immediately and
+  // block until they are completed.
+  sync FlushRendering(RenderReasons aReasons);
+
+  // Same as FlushRendering, but asynchronous, since not all platforms require
+  // synchronous repaints on resize.
+  async FlushRenderingAsync(RenderReasons aReasons);
+
+  // Make sure any pending composites have been received.
+  sync WaitOnTransactionProcessed();
+
+  // Force an additional frame presentation to be executed. This is used to
+  // work around a windows presentation bug (See Bug 1232042)
+  async ForcePresent(RenderReasons aReasons);
+
+  sync StartFrameTimeRecording(int32_t bufferSize)
+    returns (uint32_t startIndex);
+
+  sync StopFrameTimeRecording(uint32_t startIndex)
+    returns (float[] intervals);
+
+  async PTexture(SurfaceDescriptor aSharedData, ReadLockDescriptor aReadLock, LayersBackend aBackend, TextureFlags aTextureFlags, LayersId id, uint64_t aSerial, MaybeExternalImageId aExternalImageId);
+
+  sync SyncWithCompositor();
+
+  // The pipelineId is the same as the layersId
+  async PWebRenderBridge(PipelineId pipelineId, LayoutDeviceIntSize aSize, WindowKind aKind);
+
+  sync CheckContentOnlyTDR(uint32_t sequenceNum)
+    returns (bool isContentOnlyTDR);
+
+  async BeginRecording(TimeStamp aRecordingStart)
+    returns (bool success);
+
+  async EndRecording()
+    returns (FrameRecording? recording);
+
+  // To set up sharing the composited output to Firefox Reality on Desktop
+  async RequestFxrOutput();
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PCompositorBridgeTypes.ipdlh b/gfx/layers/ipc/PCompositorBridgeTypes.ipdlh
new file mode 100644
index 0000000000..f07a7a3fb0
--- /dev/null
+++ b/gfx/layers/ipc/PCompositorBridgeTypes.ipdlh
@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+using mozilla::TimeStamp from "mozilla/TimeStamp.h";
+[MoveOnly] using class mozilla::ipc::BigBuffer from "mozilla/ipc/BigBuffer.h";
+
+namespace mozilla {
+namespace layers {
+
+struct RecordedFrameData {
+  TimeStamp timeOffset;
+  uint32_t length;
+};
+
+struct FrameRecording {
+  TimeStamp startTime;
+  RecordedFrameData[] frames;
+  BigBuffer bytes;
+};
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/PCompositorManager.ipdl b/gfx/layers/ipc/PCompositorManager.ipdl
new file mode 100644
index 0000000000..02045511a7
--- /dev/null
+++ b/gfx/layers/ipc/PCompositorManager.ipdl
@@ -0,0 +1,96 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include protocol PCanvasManager;
+include protocol PCompositorBridge;
+include LayersSurfaces;
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+
+using mozilla::TimeDuration from "mozilla/TimeStamp.h";
+using mozilla::CSSToLayoutDeviceScale from "Units.h";
+using mozilla::gfx::IntSize from "mozilla/gfx/2D.h";
+[MoveOnly] using mozilla::ipc::SharedMemoryBasic::Handle from "mozilla/ipc/SharedMemoryBasic.h";
+using mozilla::layers::CompositorOptions from "mozilla/layers/LayersMessageUtils.h";
+using mozilla::wr::ExternalImageId from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::MemoryReport from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::WebRenderError from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::layers::SharedSurfacesMemoryReport from "mozilla/layers/SharedSurfacesMemoryReport.h";
+
+namespace mozilla {
+namespace layers {
+
+struct WidgetCompositorOptions {
+  CSSToLayoutDeviceScale scale;
+  TimeDuration vsyncRate;
+  CompositorOptions options;
+  bool useExternalSurfaceSize;
+  IntSize surfaceSize;
+  uint64_t innerWindowId;
+};
+
+struct ContentCompositorOptions {
+};
+
+struct SameProcessWidgetCompositorOptions {
+};
+
+union CompositorBridgeOptions {
+  ContentCompositorOptions;
+  WidgetCompositorOptions;
+  SameProcessWidgetCompositorOptions;
+};
+
+/**
+ * The PCompositorManager protocol is the top-level protocol between the
+ * compositor thread and the creators of compositors. It exists in the
+ * following conditions:
+ * - One PCompositorManager between the GPU process and each content process.
+ *   If the GPU/UI processes are combined, there is one PCompositorManager
+ *   between the combined GPU/UI process and each content process.
+ * - One PCompositorManager between the GPU process and the UI process. If
+ *   they are combined, there is still one PCompositorManager, but both the
+ *   child and parent live in the same process.
+ * The intention for this protocol is to facilitate communication with the
+ * compositor thread for compositor data that is only shared once, rather than
+ * per PCompositorBridge instance.
+ */
+[NeedsOtherPid, ParentProc=compositor, ChildProc=anydom]
+sync protocol PCompositorManager
+{
+  manages PCompositorBridge;
+
+parent:
+  /**
+   * There are three variants of a PCompositorBridge protocol, each of which can
+   * only be created by certain processes and configurations:
+   * - A "content" PCompositorBridge is requested by each content process,
+   *   representing the drawable area for Web content.
+   * - A "widget" PCompositorBridge is requested by the UI process for each
+   *   "top level browser window" for chrome and such.
+   * - A "same process widget" PCompositorBridge is requested by the combined
+   *   GPU/UI process for each "top level browser window" as above.
+   * See gfx/layers/ipc/PCompositorBridge.ipdl for more details.
+   */
+  async PCompositorBridge(CompositorBridgeOptions options);
+
+  async AddSharedSurface(ExternalImageId aId, SurfaceDescriptorShared aDesc);
+  async RemoveSharedSurface(ExternalImageId aId);
+  async ReportSharedSurfacesMemory() returns (SharedSurfacesMemoryReport aReport);
+
+  async NotifyMemoryPressure();
+
+  async ReportMemory() returns (MemoryReport aReport);
+
+  async InitCanvasManager(Endpoint<PCanvasManagerParent> endpoint);
+
+child:
+  async NotifyWebRenderError(WebRenderError error);
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PImageBridge.ipdl b/gfx/layers/ipc/PImageBridge.ipdl
new file mode 100644
index 0000000000..8af889d8ac
--- /dev/null
+++ b/gfx/layers/ipc/PImageBridge.ipdl
@@ -0,0 +1,65 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include LayersMessages;
+include protocol PTexture;
+include ProtocolTypes;
+include protocol PMediaSystemResourceManager;
+
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+
+using struct mozilla::layers::TextureInfo from "mozilla/layers/CompositorTypes.h";
+using mozilla::layers::TextureFlags from "mozilla/layers/CompositorTypes.h";
+using mozilla::layers::CompositableHandle from "mozilla/layers/LayersTypes.h";
+using mozilla::wr::MaybeExternalImageId from "mozilla/webrender/WebRenderTypes.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * The PImageBridge protocol is used to allow isolated threads or processes to push
+ * frames directly to the compositor thread/process without relying on the main thread
+ * which might be too busy dealing with content script.
+ */
+[NeedsOtherPid, ParentProc=compositor, ChildProc=anydom]
+sync protocol PImageBridge
+{
+  manages PTexture;
+  manages PMediaSystemResourceManager;
+
+child:
+  async ParentAsyncMessages(AsyncParentMessageData[] aMessages);
+
+  async DidComposite(ImageCompositeNotification[] aNotifications);
+
+  // Report the number of frames dropped for the given CompositableHost.
+  async ReportFramesDropped(CompositableHandle aHandle, uint32_t aFrames);
+
+parent:
+  async Update(CompositableOperation[] ops, OpDestroy[] toDestroy, uint64_t fwdTransactionId);
+
+  // First step of the destruction sequence. This puts ImageBridge
+  // in a state in which it can't send asynchronous messages
+  // so as to not race with the channel getting closed.
+  // In the child side, the Closing the channel does not happen right after WillClose,
+  // it is scheduled in the ImageBridgeChild's message queue in order to ensure
+  // that all of the messages from the parent side have been received and processed
+  // before sending closing the channel.
+  async WillClose();
+
+  async PTexture(SurfaceDescriptor aSharedData, ReadLockDescriptor aReadLock, LayersBackend aBackend, TextureFlags aTextureFlags, uint64_t aSerial, MaybeExternalImageId aExternalImageId);
+  async PMediaSystemResourceManager();
+
+  sync NewCompositable(CompositableHandle aHandle, TextureInfo aInfo);
+  async ReleaseCompositable(CompositableHandle aHandle);
+};
+
+
+} // namespace
+} // namespace
+
diff --git a/gfx/layers/ipc/PTexture.ipdl b/gfx/layers/ipc/PTexture.ipdl
new file mode 100644
index 0000000000..ad6cf8fc13
--- /dev/null
+++ b/gfx/layers/ipc/PTexture.ipdl
@@ -0,0 +1,40 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include protocol PCompositorBridge;
+include protocol PImageBridge;
+include protocol PVideoBridge;
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+
+using mozilla::layers::TextureFlags from "mozilla/layers/CompositorTypes.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * PTexture is the IPDL glue between a TextureClient and a TextureHost.
+ */
+[ManualDealloc, ChildImpl=virtual, ParentImpl=virtual]
+sync protocol PTexture {
+    manager PImageBridge or PCompositorBridge or PVideoBridge;
+
+child:
+    async __delete__();
+
+parent:
+    /**
+     * Asynchronously tell the compositor side to remove the texture.
+     */
+    async Destroy();
+
+    async RecycleTexture(TextureFlags aTextureFlags);
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PUiCompositorController.ipdl b/gfx/layers/ipc/PUiCompositorController.ipdl
new file mode 100644
index 0000000000..5aa75bf7da
--- /dev/null
+++ b/gfx/layers/ipc/PUiCompositorController.ipdl
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+using mozilla::CSSRect from "Units.h";
+using mozilla::CSSToScreenScale from "Units.h";
+using mozilla::ScreenIntSize from "Units.h";
+using mozilla::ScreenPoint from "Units.h";
+
+include "mozilla/GfxMessageUtils.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * The PUiCompositorController protocol is used to pause and resume the
+ * compositor from the UI thread. Primarily used on Android to coordinate registering and
+ * releasing the surface with the compositor.
+ */
+[NeedsOtherPid, ParentProc=compositor, ChildProc=Parent]
+sync protocol PUiCompositorController
+{
+
+parent:
+  // Pause/resume the compositor. These are intended to be used on mobile, when
+  // the compositor needs to pause/resume in lockstep with the application.
+  sync Pause();
+  sync Resume() returns (bool aOutResumed);
+  sync ResumeAndResize(int32_t aX, int32_t aY, int32_t aWidth, int32_t aHeight)
+    returns (bool aOutResumed);
+
+  async InvalidateAndRender();
+  async MaxToolbarHeight(int32_t aHeight);
+  async FixedBottomOffset(int32_t aOffset);
+  async DefaultClearColor(uint32_t aColor);
+  async RequestScreenPixels();
+  async EnableLayerUpdateNotifications(bool aEnable);
+child:
+  async ToolbarAnimatorMessageFromCompositor(int32_t aMessage);
+  async RootFrameMetrics(ScreenPoint aScrollOffset, CSSToScreenScale aZoom);
+  async ScreenPixels(Shmem aMem, ScreenIntSize aSize, bool aNeedsYFlip);
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/PVideoBridge.ipdl b/gfx/layers/ipc/PVideoBridge.ipdl
new file mode 100644
index 0000000000..eb9d7dafee
--- /dev/null
+++ b/gfx/layers/ipc/PVideoBridge.ipdl
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include LayersMessages;
+include protocol PTexture;
+
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/LayersMessageUtils.h";
+
+using mozilla::dom::ContentParentId from "mozilla/dom/ipc/IdType.h";
+using mozilla::layers::TextureFlags from "mozilla/layers/CompositorTypes.h";
+using mozilla::void_t from "mozilla/ipc/IPCCore.h";
+
+namespace mozilla {
+namespace layers {
+
+/**
+ * The PVideoBridge protocol is used to share textures from the video decoders
+ * to the compositor.
+ */
+[NeedsOtherPid, ParentProc=compositor, ChildProc=any]
+sync protocol PVideoBridge
+{
+  manages PTexture;
+
+child:
+  async Ping() returns (void_t ok);
+
+parent:
+  /**
+   * Since PVideoBridge creates textures on behalf of another process, we also
+   * supply ContentParentId of the owning content process.
+   */
+  async PTexture(SurfaceDescriptor aSharedData, ReadLockDescriptor aReadLock, LayersBackend aBackend,
+                 TextureFlags aTextureFlags, ContentParentId aContentId, uint64_t aSerial);
+};
+
+} // namespace
+} // namespace
+
diff --git a/gfx/layers/ipc/PWebRenderBridge.ipdl b/gfx/layers/ipc/PWebRenderBridge.ipdl
new file mode 100644
index 0000000000..8e5c56b7cb
--- /dev/null
+++ b/gfx/layers/ipc/PWebRenderBridge.ipdl
@@ -0,0 +1,137 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include LayersSurfaces;
+include LayersMessages;
+include "mozilla/GfxMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+
+include WebRenderMessages;
+include protocol PCompositorBridge;
+include protocol PTexture;
+
+using mozilla::layers::APZTestData from "mozilla/layers/APZTestData.h";
+using mozilla::layers::FrameUniformityData from "mozilla/layers/FrameUniformityData.h";
+using mozilla::layers::ScrollableLayerGuid from "mozilla/layers/ScrollableLayerGuid.h";
+using struct mozilla::layers::TextureFactoryIdentifier from "mozilla/layers/CompositorTypes.h";
+using struct mozilla::layers::TextureInfo from "mozilla/layers/CompositorTypes.h";
+using mozilla::layers::CompositionPayload from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::CompositableHandle from "mozilla/layers/LayersTypes.h";
+using mozilla::wr::BuiltDisplayListDescriptor from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::RenderReasons from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::IdNamespace from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::MaybeIdNamespace from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::ExternalImageKeyPair from "mozilla/webrender/WebRenderTypes.h";
+[MoveOnly] using mozilla::layers::DisplayListData from "mozilla/layers/RenderRootTypes.h";
+[MoveOnly] using mozilla::layers::MaybeTransactionData from "mozilla/layers/RenderRootTypes.h";
+using mozilla::layers::FocusTarget from "mozilla/layers/FocusTarget.h";
+using mozilla::layers::TransactionId from "mozilla/layers/LayersTypes.h";
+using mozilla::VsyncId from "mozilla/VsyncDispatcher.h";
+
+namespace mozilla {
+namespace layers {
+
+[ManualDealloc, ParentImpl=virtual]
+sync protocol PWebRenderBridge
+{
+  manager PCompositorBridge;
+
+parent:
+  sync EnsureConnected()
+    returns (TextureFactoryIdentifier textureFactoryIdentifier, MaybeIdNamespace maybeIdNamespace, nsCString error);
+
+  async NewCompositable(CompositableHandle handle, TextureInfo info);
+  async ReleaseCompositable(CompositableHandle compositable);
+
+  async DeleteCompositorAnimations(uint64_t[] aIds);
+  async SetDisplayList(DisplayListData displayList,
+                       OpDestroy[] toDestroy, uint64_t fwdTransactionId, TransactionId transactionId,
+                       bool containsSVGGroup,
+                       VsyncId vsyncId, TimeStamp vsyncStartTime,
+                       TimeStamp refreshStartTime, TimeStamp txnStartTime, nsCString txnURL, TimeStamp fwdTime,
+                       CompositionPayload[] payloads);
+  async EmptyTransaction(FocusTarget focusTarget,
+                         MaybeTransactionData transationData,
+                         OpDestroy[] toDestroy, uint64_t fwdTransactionId, TransactionId transactionId,
+                         VsyncId vsyncId, TimeStamp vsyncStartTime,
+                         TimeStamp refreshStartTime, TimeStamp txnStartTime,
+                         nsCString txnURL, TimeStamp fwdTime,
+                         CompositionPayload[] payloads);
+  async SetFocusTarget(FocusTarget focusTarget);
+  async UpdateResources(IdNamespace aIdNamespace, OpUpdateResource[] aResourceUpdates,
+                        RefCountedShmem[] aSmallShmems, Shmem[] aLargeShmems);
+  async ParentCommands(IdNamespace aIdNamespace, WebRenderParentCommand[] commands);
+  sync GetSnapshot(PTexture texture) returns (bool aNeedsYFlip);
+  async ClearCachedResources();
+  async ClearAnimationResources();
+  async SetDefaultClearColor(uint32_t aColor);
+  // Invalidate rendered frame
+  async InvalidateRenderedFrame();
+  // Schedule a composite if one isn't already scheduled.
+  async ScheduleComposite(RenderReasons aReasons);
+  // Save the frame capture to disk
+  async Capture();
+
+  // Start capturing each frame to disk. See
+  // nsIDOMWindowUtils::wrStartCaptureSequence for documentation.
+  async StartCaptureSequence(nsCString aPath, uint32_t aFlags);
+
+  // Stop the captures started by StartCaptureSequence. See
+  // nsIDOMWindowUtils::wrStopCaptureSequence for documentation.
+  async StopCaptureSequence();
+
+  // Replacement for PCompositorBridge::SyncWithCompositor, but for WR. We need
+  // it on PWebRenderBridge because it associated with a particular top-level
+  // window, and PCompositorBridge doesn't allow doing that in a secure manner.
+  sync SyncWithCompositor();
+
+  // Tell the compositor to notify APZ that a target scroll frame has been
+  // confirmed for an input event.
+  async SetConfirmedTargetAPZC(uint64_t aInputBlockId, ScrollableLayerGuid[] aTargets);
+
+  // Testing APIs
+
+  // Enter test mode, set the sample time to sampleTime, and resample
+  // animations. sampleTime must not be null.
+  sync SetTestSampleTime(TimeStamp sampleTime);
+  // Leave test mode and resume normal compositing
+  sync LeaveTestMode();
+
+  // Returns the |OMTAValue| for the compositor animation with the given id.
+  sync GetAnimationValue(uint64_t aCompositorAnimationsId) returns (OMTAValue value);
+
+  // The next time the display list tree is composited, add this async scroll offset
+  // in CSS pixels for the given ViewID.
+  // Useful for testing rendering of async scrolling.
+  sync SetAsyncScrollOffset(ViewID scrollId, float x, float y);
+
+  // The next time the display list is composited, include this async zoom in
+  // for the given ViewID.
+  // Useful for testing rendering of async zooming.
+  sync SetAsyncZoom(ViewID scrollId, float zoom);
+
+  // Flush any pending APZ repaints to the main thread.
+  async FlushApzRepaints();
+
+  // Get a copy of the compositor-side APZ test data instance for this
+  // layers id.
+  sync GetAPZTestData() returns (APZTestData data);
+
+  // Child requests frame uniformity measurements
+  sync GetFrameUniformity() returns (FrameUniformityData data);
+
+
+  async Shutdown();
+  sync ShutdownSync();
+child:
+  async WrUpdated(IdNamespace aNewIdNamespace, TextureFactoryIdentifier textureFactoryIdentifier);
+  async WrReleasedImages(ExternalImageKeyPair[] pairs);
+  async __delete__();
+};
+
+} // layers
+} // mozilla
diff --git a/gfx/layers/ipc/RefCountedShmem.cpp b/gfx/layers/ipc/RefCountedShmem.cpp
new file mode 100644
index 0000000000..8eec82dc9a
--- /dev/null
+++ b/gfx/layers/ipc/RefCountedShmem.cpp
@@ -0,0 +1,93 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "RefCountedShmem.h"
+
+#include "mozilla/Atomics.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/layers/WebRenderMessages.h"
+
+#define SHM_REFCOUNT_HEADER_SIZE 16
+
+namespace mozilla {
+namespace layers {
+
+uint8_t* RefCountedShm::GetBytes(const RefCountedShmem& aShm) {
+  uint8_t* data = aShm.buffer().get<uint8_t>();
+  if (!data) {
+    return nullptr;
+  }
+  return data + SHM_REFCOUNT_HEADER_SIZE;
+}
+
+size_t RefCountedShm::GetSize(const RefCountedShmem& aShm) {
+  if (!IsValid(aShm)) {
+    return 0;
+  }
+  size_t totalSize = aShm.buffer().Size<uint8_t>();
+  if (totalSize < SHM_REFCOUNT_HEADER_SIZE) {
+    return 0;
+  }
+
+  return totalSize - SHM_REFCOUNT_HEADER_SIZE;
+}
+
+bool RefCountedShm::IsValid(const RefCountedShmem& aShm) {
+  return aShm.buffer().IsWritable() &&
+         aShm.buffer().Size<uint8_t>() > SHM_REFCOUNT_HEADER_SIZE;
+}
+
+int32_t RefCountedShm::GetReferenceCount(const RefCountedShmem& aShm) {
+  if (!IsValid(aShm)) {
+    return 0;
+  }
+
+  return *aShm.buffer().get<Atomic<int32_t>>();
+}
+
+int32_t RefCountedShm::AddRef(const RefCountedShmem& aShm) {
+  if (!IsValid(aShm)) {
+    return 0;
+  }
+
+  auto* counter = aShm.buffer().get<Atomic<int32_t>>();
+  if (counter) {
+    return (*counter)++;
+  }
+  return 0;
+}
+
+int32_t RefCountedShm::Release(const RefCountedShmem& aShm) {
+  if (!IsValid(aShm)) {
+    return 0;
+  }
+
+  auto* counter = aShm.buffer().get<Atomic<int32_t>>();
+  if (counter) {
+    return --(*counter);
+  }
+
+  return 0;
+}
+
+bool RefCountedShm::Alloc(mozilla::ipc::IProtocol* aAllocator, size_t aSize,
+                          RefCountedShmem& aShm) {
+  MOZ_ASSERT(!IsValid(aShm));
+  auto size = aSize + SHM_REFCOUNT_HEADER_SIZE;
+  if (!aAllocator->AllocUnsafeShmem(size, &aShm.buffer())) {
+    return false;
+  }
+  return true;
+}
+
+void RefCountedShm::Dealloc(mozilla::ipc::IProtocol* aAllocator,
+                            RefCountedShmem& aShm) {
+  aAllocator->DeallocShmem(aShm.buffer());
+  aShm.buffer() = ipc::Shmem();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/RefCountedShmem.h b/gfx/layers/ipc/RefCountedShmem.h
new file mode 100644
index 0000000000..390d6ea25f
--- /dev/null
+++ b/gfx/layers/ipc/RefCountedShmem.h
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_REFCOUNTED_SHMEM_H
+#define MOZILLA_LAYERS_REFCOUNTED_SHMEM_H
+
+#include "mozilla/ipc/Shmem.h"
+#include "chrome/common/ipc_message_utils.h"
+
+namespace mozilla {
+namespace ipc {
+class IProtocol;
+}
+
+namespace layers {
+
+// This class is IPDL-defined
+class RefCountedShmem;
+
+// This just implement the methods externally.
+class RefCountedShm {
+ public:
+  static uint8_t* GetBytes(const RefCountedShmem& aShm);
+
+  static size_t GetSize(const RefCountedShmem& aShm);
+
+  static bool IsValid(const RefCountedShmem& aShm);
+
+  static bool Alloc(mozilla::ipc::IProtocol* aAllocator, size_t aSize,
+                    RefCountedShmem& aShm);
+
+  static void Dealloc(mozilla::ipc::IProtocol* aAllocator,
+                      RefCountedShmem& aShm);
+
+  static int32_t GetReferenceCount(const RefCountedShmem& aShm);
+
+  static int32_t AddRef(const RefCountedShmem& aShm);
+
+  static int32_t Release(const RefCountedShmem& aShm);
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/RemoteContentController.cpp b/gfx/layers/ipc/RemoteContentController.cpp
new file mode 100644
index 0000000000..682331362b
--- /dev/null
+++ b/gfx/layers/ipc/RemoteContentController.cpp
@@ -0,0 +1,526 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/RemoteContentController.h"
+
+#include "CompositorThread.h"
+#include "MainThreadUtils.h"
+#include "mozilla/dom/BrowserParent.h"
+#include "mozilla/layers/APZCCallbackHelper.h"
+#include "mozilla/layers/APZCTreeManagerParent.h"  // for APZCTreeManagerParent
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/layers/DoubleTapToZoom.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/MatrixMessage.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/Unused.h"
+#include "Units.h"
+#ifdef MOZ_WIDGET_ANDROID
+#  include "mozilla/jni/Utils.h"
+#endif
+
+static mozilla::LazyLogModule sApzRemoteLog("apz.cc.remote");
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::gfx;
+
+RemoteContentController::RemoteContentController()
+    : mCompositorThread(NS_GetCurrentThread()), mCanSend(true) {
+  MOZ_ASSERT(CompositorThread()->IsOnCurrentThread());
+}
+
+RemoteContentController::~RemoteContentController() = default;
+
+void RemoteContentController::NotifyLayerTransforms(
+    nsTArray<MatrixMessage>&& aTransforms) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(
+        NewRunnableMethod<StoreCopyPassByRRef<nsTArray<MatrixMessage>>>(
+            "layers::RemoteContentController::NotifyLayerTransforms", this,
+            &RemoteContentController::NotifyLayerTransforms,
+            std::move(aTransforms)));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendLayerTransforms(aTransforms);
+  }
+}
+
+void RemoteContentController::RequestContentRepaint(
+    const RepaintRequest& aRequest) {
+  MOZ_ASSERT(IsRepaintThread());
+
+  if (mCanSend) {
+    Unused << SendRequestContentRepaint(aRequest);
+  }
+}
+
+void RemoteContentController::HandleTapOnMainThread(
+    TapType aTapType, LayoutDevicePoint aPoint, Modifiers aModifiers,
+    ScrollableLayerGuid aGuid, uint64_t aInputBlockId,
+    const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics) {
+  MOZ_LOG(sApzRemoteLog, LogLevel::Debug,
+          ("HandleTapOnMainThread(%d)", (int)aTapType));
+  MOZ_ASSERT(NS_IsMainThread());
+
+  dom::BrowserParent* tab =
+      dom::BrowserParent::GetBrowserParentFromLayersId(aGuid.mLayersId);
+  if (tab) {
+    tab->SendHandleTap(aTapType, aPoint, aModifiers, aGuid, aInputBlockId,
+                       aDoubleTapToZoomMetrics);
+  }
+}
+
+void RemoteContentController::HandleTapOnCompositorThread(
+    TapType aTapType, LayoutDevicePoint aPoint, Modifiers aModifiers,
+    ScrollableLayerGuid aGuid, uint64_t aInputBlockId,
+    const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics) {
+  MOZ_ASSERT(XRE_IsGPUProcess());
+  MOZ_ASSERT(mCompositorThread->IsOnCurrentThread());
+
+  // The raw pointer to APZCTreeManagerParent is ok here because we are on
+  // the compositor thread.
+  APZCTreeManagerParent* apzctmp =
+      CompositorBridgeParent::GetApzcTreeManagerParentForRoot(aGuid.mLayersId);
+  if (apzctmp) {
+    Unused << apzctmp->SendHandleTap(aTapType, aPoint, aModifiers, aGuid,
+                                     aInputBlockId, aDoubleTapToZoomMetrics);
+  }
+}
+
+void RemoteContentController::HandleTap(
+    TapType aTapType, const LayoutDevicePoint& aPoint, Modifiers aModifiers,
+    const ScrollableLayerGuid& aGuid, uint64_t aInputBlockId,
+    const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics) {
+  MOZ_LOG(sApzRemoteLog, LogLevel::Debug, ("HandleTap(%d)", (int)aTapType));
+  APZThreadUtils::AssertOnControllerThread();
+
+  if (XRE_GetProcessType() == GeckoProcessType_GPU) {
+    if (mCompositorThread->IsOnCurrentThread()) {
+      HandleTapOnCompositorThread(aTapType, aPoint, aModifiers, aGuid,
+                                  aInputBlockId, aDoubleTapToZoomMetrics);
+    } else {
+      // We have to send messages from the compositor thread
+      mCompositorThread->Dispatch(
+          NewRunnableMethod<TapType, LayoutDevicePoint, Modifiers,
+                            ScrollableLayerGuid, uint64_t,
+                            Maybe<DoubleTapToZoomMetrics>>(
+              "layers::RemoteContentController::HandleTapOnCompositorThread",
+              this, &RemoteContentController::HandleTapOnCompositorThread,
+              aTapType, aPoint, aModifiers, aGuid, aInputBlockId,
+              aDoubleTapToZoomMetrics));
+    }
+    return;
+  }
+
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (NS_IsMainThread()) {
+    HandleTapOnMainThread(aTapType, aPoint, aModifiers, aGuid, aInputBlockId,
+                          aDoubleTapToZoomMetrics);
+  } else {
+    // We must be on Android, running on the Java UI thread
+#ifndef MOZ_WIDGET_ANDROID
+    MOZ_ASSERT(false);
+#else
+    // We don't want to get the BrowserParent or call
+    // BrowserParent::SendHandleTap() from a non-main thread, so we need to
+    // redispatch to the main thread. However, we should use the same
+    // mechanism that the Android widget uses when dispatching input events
+    // to Gecko, which is nsAppShell::PostEvent. Note in particular that
+    // using NS_DispatchToMainThread would post to a different message loop,
+    // and introduces the possibility of this tap event getting processed
+    // out of order with respect to the touch events that synthesized it.
+    mozilla::jni::DispatchToGeckoPriorityQueue(
+        NewRunnableMethod<TapType, LayoutDevicePoint, Modifiers,
+                          ScrollableLayerGuid, uint64_t,
+                          Maybe<DoubleTapToZoomMetrics>>(
+            "layers::RemoteContentController::HandleTapOnMainThread", this,
+            &RemoteContentController::HandleTapOnMainThread, aTapType, aPoint,
+            aModifiers, aGuid, aInputBlockId, aDoubleTapToZoomMetrics));
+#endif
+  }
+}
+
+void RemoteContentController::NotifyPinchGestureOnCompositorThread(
+    PinchGestureInput::PinchGestureType aType, const ScrollableLayerGuid& aGuid,
+    const LayoutDevicePoint& aFocusPoint, LayoutDeviceCoord aSpanChange,
+    Modifiers aModifiers) {
+  MOZ_ASSERT(mCompositorThread->IsOnCurrentThread());
+
+  // The raw pointer to APZCTreeManagerParent is ok here because we are on
+  // the compositor thread.
+  APZCTreeManagerParent* apzctmp =
+      CompositorBridgeParent::GetApzcTreeManagerParentForRoot(aGuid.mLayersId);
+  if (apzctmp) {
+    Unused << apzctmp->SendNotifyPinchGesture(aType, aGuid, aFocusPoint,
+                                              aSpanChange, aModifiers);
+  }
+}
+
+void RemoteContentController::NotifyPinchGesture(
+    PinchGestureInput::PinchGestureType aType, const ScrollableLayerGuid& aGuid,
+    const LayoutDevicePoint& aFocusPoint, LayoutDeviceCoord aSpanChange,
+    Modifiers aModifiers) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  // For now we only ever want to handle this NotifyPinchGesture message in
+  // the parent process, even if the APZ is sending it to a content process.
+
+  // If we're in the GPU process, try to find a handle to the parent process
+  // and send it there.
+  if (XRE_IsGPUProcess()) {
+    if (mCompositorThread->IsOnCurrentThread()) {
+      NotifyPinchGestureOnCompositorThread(aType, aGuid, aFocusPoint,
+                                           aSpanChange, aModifiers);
+    } else {
+      mCompositorThread->Dispatch(
+          NewRunnableMethod<PinchGestureInput::PinchGestureType,
+                            ScrollableLayerGuid, LayoutDevicePoint,
+                            LayoutDeviceCoord, Modifiers>(
+              "layers::RemoteContentController::"
+              "NotifyPinchGestureOnCompositorThread",
+              this,
+              &RemoteContentController::NotifyPinchGestureOnCompositorThread,
+              aType, aGuid, aFocusPoint, aSpanChange, aModifiers));
+    }
+    return;
+  }
+
+  // If we're in the parent process, handle it directly. We don't have a
+  // handle to the widget though, so we fish out the ChromeProcessController
+  // and delegate to that instead.
+  if (XRE_IsParentProcess()) {
+    MOZ_ASSERT(NS_IsMainThread());
+    RefPtr<GeckoContentController> rootController =
+        CompositorBridgeParent::GetGeckoContentControllerForRoot(
+            aGuid.mLayersId);
+    if (rootController) {
+      rootController->NotifyPinchGesture(aType, aGuid, aFocusPoint, aSpanChange,
+                                         aModifiers);
+    }
+  }
+}
+
+bool RemoteContentController::IsRepaintThread() {
+  return mCompositorThread->IsOnCurrentThread();
+}
+
+void RemoteContentController::DispatchToRepaintThread(
+    already_AddRefed<Runnable> aTask) {
+  mCompositorThread->Dispatch(std::move(aTask));
+}
+
+void RemoteContentController::NotifyAPZStateChange(
+    const ScrollableLayerGuid& aGuid, APZStateChange aChange, int aArg,
+    Maybe<uint64_t> aInputBlockId) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(
+        NewRunnableMethod<ScrollableLayerGuid, APZStateChange, int,
+                          Maybe<uint64_t>>(
+            "layers::RemoteContentController::NotifyAPZStateChange", this,
+            &RemoteContentController::NotifyAPZStateChange, aGuid, aChange,
+            aArg, aInputBlockId));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendNotifyAPZStateChange(aGuid, aChange, aArg, aInputBlockId);
+  }
+}
+
+void RemoteContentController::UpdateOverscrollVelocity(
+    const ScrollableLayerGuid& aGuid, float aX, float aY, bool aIsRootContent) {
+  if (XRE_IsParentProcess()) {
+#ifdef MOZ_WIDGET_ANDROID
+    // We always want these to go to the parent process on Android
+    if (!NS_IsMainThread()) {
+      mozilla::jni::DispatchToGeckoPriorityQueue(
+          NewRunnableMethod<ScrollableLayerGuid, float, float, bool>(
+              "layers::RemoteContentController::UpdateOverscrollVelocity", this,
+              &RemoteContentController::UpdateOverscrollVelocity, aGuid, aX, aY,
+              aIsRootContent));
+      return;
+    }
+#endif
+
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+    RefPtr<GeckoContentController> rootController =
+        CompositorBridgeParent::GetGeckoContentControllerForRoot(
+            aGuid.mLayersId);
+    if (rootController) {
+      rootController->UpdateOverscrollVelocity(aGuid, aX, aY, aIsRootContent);
+    }
+  } else if (XRE_IsGPUProcess()) {
+    if (!mCompositorThread->IsOnCurrentThread()) {
+      mCompositorThread->Dispatch(
+          NewRunnableMethod<ScrollableLayerGuid, float, float, bool>(
+              "layers::RemoteContentController::UpdateOverscrollVelocity", this,
+              &RemoteContentController::UpdateOverscrollVelocity, aGuid, aX, aY,
+              aIsRootContent));
+      return;
+    }
+
+    MOZ_RELEASE_ASSERT(mCompositorThread->IsOnCurrentThread());
+    GeckoContentController* rootController =
+        CompositorBridgeParent::GetGeckoContentControllerForRoot(
+            aGuid.mLayersId);
+    if (rootController) {
+      MOZ_RELEASE_ASSERT(rootController->IsRemote());
+      Unused << static_cast<RemoteContentController*>(rootController)
+                    ->SendUpdateOverscrollVelocity(aGuid, aX, aY,
+                                                   aIsRootContent);
+    }
+  }
+}
+
+void RemoteContentController::UpdateOverscrollOffset(
+    const ScrollableLayerGuid& aGuid, float aX, float aY, bool aIsRootContent) {
+  if (XRE_IsParentProcess()) {
+#ifdef MOZ_WIDGET_ANDROID
+    // We always want these to go to the parent process on Android
+    if (!NS_IsMainThread()) {
+      mozilla::jni::DispatchToGeckoPriorityQueue(
+          NewRunnableMethod<ScrollableLayerGuid, float, float, bool>(
+              "layers::RemoteContentController::UpdateOverscrollOffset", this,
+              &RemoteContentController::UpdateOverscrollOffset, aGuid, aX, aY,
+              aIsRootContent));
+      return;
+    }
+#endif
+
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
+    RefPtr<GeckoContentController> rootController =
+        CompositorBridgeParent::GetGeckoContentControllerForRoot(
+            aGuid.mLayersId);
+    if (rootController) {
+      rootController->UpdateOverscrollOffset(aGuid, aX, aY, aIsRootContent);
+    }
+  } else if (XRE_IsGPUProcess()) {
+    if (!mCompositorThread->IsOnCurrentThread()) {
+      mCompositorThread->Dispatch(
+          NewRunnableMethod<ScrollableLayerGuid, float, float, bool>(
+              "layers::RemoteContentController::UpdateOverscrollOffset", this,
+              &RemoteContentController::UpdateOverscrollOffset, aGuid, aX, aY,
+              aIsRootContent));
+      return;
+    }
+
+    MOZ_RELEASE_ASSERT(mCompositorThread->IsOnCurrentThread());
+    GeckoContentController* rootController =
+        CompositorBridgeParent::GetGeckoContentControllerForRoot(
+            aGuid.mLayersId);
+    if (rootController) {
+      MOZ_RELEASE_ASSERT(rootController->IsRemote());
+      Unused << static_cast<RemoteContentController*>(rootController)
+                    ->SendUpdateOverscrollOffset(aGuid, aX, aY, aIsRootContent);
+    }
+  }
+}
+
+void RemoteContentController::NotifyMozMouseScrollEvent(
+    const ScrollableLayerGuid::ViewID& aScrollId, const nsString& aEvent) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(
+        NewRunnableMethod<ScrollableLayerGuid::ViewID, nsString>(
+            "layers::RemoteContentController::NotifyMozMouseScrollEvent", this,
+            &RemoteContentController::NotifyMozMouseScrollEvent, aScrollId,
+            aEvent));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendNotifyMozMouseScrollEvent(aScrollId, aEvent);
+  }
+}
+
+void RemoteContentController::NotifyFlushComplete() {
+  MOZ_ASSERT(IsRepaintThread());
+
+  if (mCanSend) {
+    Unused << SendNotifyFlushComplete();
+  }
+}
+
+void RemoteContentController::NotifyAsyncScrollbarDragInitiated(
+    uint64_t aDragBlockId, const ScrollableLayerGuid::ViewID& aScrollId,
+    ScrollDirection aDirection) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(
+        NewRunnableMethod<uint64_t, ScrollableLayerGuid::ViewID,
+                          ScrollDirection>(
+            "layers::RemoteContentController::"
+            "NotifyAsyncScrollbarDragInitiated",
+            this, &RemoteContentController::NotifyAsyncScrollbarDragInitiated,
+            aDragBlockId, aScrollId, aDirection));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendNotifyAsyncScrollbarDragInitiated(aDragBlockId, aScrollId,
+                                                    aDirection);
+  }
+}
+
+void RemoteContentController::NotifyAsyncScrollbarDragRejected(
+    const ScrollableLayerGuid::ViewID& aScrollId) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(NewRunnableMethod<ScrollableLayerGuid::ViewID>(
+        "layers::RemoteContentController::NotifyAsyncScrollbarDragRejected",
+        this, &RemoteContentController::NotifyAsyncScrollbarDragRejected,
+        aScrollId));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendNotifyAsyncScrollbarDragRejected(aScrollId);
+  }
+}
+
+void RemoteContentController::NotifyAsyncAutoscrollRejected(
+    const ScrollableLayerGuid::ViewID& aScrollId) {
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    // We have to send messages from the compositor thread
+    mCompositorThread->Dispatch(NewRunnableMethod<ScrollableLayerGuid::ViewID>(
+        "layers::RemoteContentController::NotifyAsyncAutoscrollRejected", this,
+        &RemoteContentController::NotifyAsyncAutoscrollRejected, aScrollId));
+    return;
+  }
+
+  if (mCanSend) {
+    Unused << SendNotifyAsyncAutoscrollRejected(aScrollId);
+  }
+}
+
+void RemoteContentController::CancelAutoscroll(
+    const ScrollableLayerGuid& aGuid) {
+  if (XRE_GetProcessType() == GeckoProcessType_GPU) {
+    CancelAutoscrollCrossProcess(aGuid);
+  } else {
+    CancelAutoscrollInProcess(aGuid);
+  }
+}
+
+void RemoteContentController::CancelAutoscrollInProcess(
+    const ScrollableLayerGuid& aGuid) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (!NS_IsMainThread()) {
+    NS_DispatchToMainThread(NewRunnableMethod<ScrollableLayerGuid>(
+        "layers::RemoteContentController::CancelAutoscrollInProcess", this,
+        &RemoteContentController::CancelAutoscrollInProcess, aGuid));
+    return;
+  }
+
+  APZCCallbackHelper::CancelAutoscroll(aGuid.mScrollId);
+}
+
+void RemoteContentController::CancelAutoscrollCrossProcess(
+    const ScrollableLayerGuid& aGuid) {
+  MOZ_ASSERT(XRE_IsGPUProcess());
+
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    mCompositorThread->Dispatch(NewRunnableMethod<ScrollableLayerGuid>(
+        "layers::RemoteContentController::CancelAutoscrollCrossProcess", this,
+        &RemoteContentController::CancelAutoscrollCrossProcess, aGuid));
+    return;
+  }
+
+  // The raw pointer to APZCTreeManagerParent is ok here because we are on
+  // the compositor thread.
+  if (APZCTreeManagerParent* parent =
+          CompositorBridgeParent::GetApzcTreeManagerParentForRoot(
+              aGuid.mLayersId)) {
+    Unused << parent->SendCancelAutoscroll(aGuid.mScrollId);
+  }
+}
+
+void RemoteContentController::NotifyScaleGestureComplete(
+    const ScrollableLayerGuid& aGuid, float aScale) {
+  if (XRE_GetProcessType() == GeckoProcessType_GPU) {
+    NotifyScaleGestureCompleteCrossProcess(aGuid, aScale);
+  } else {
+    NotifyScaleGestureCompleteInProcess(aGuid, aScale);
+  }
+}
+
+void RemoteContentController::NotifyScaleGestureCompleteInProcess(
+    const ScrollableLayerGuid& aGuid, float aScale) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (!NS_IsMainThread()) {
+    NS_DispatchToMainThread(NewRunnableMethod<ScrollableLayerGuid, float>(
+        "layers::RemoteContentController::"
+        "NotifyScaleGestureCompleteInProcess",
+        this, &RemoteContentController::NotifyScaleGestureCompleteInProcess,
+        aGuid, aScale));
+    return;
+  }
+
+  RefPtr<GeckoContentController> rootController =
+      CompositorBridgeParent::GetGeckoContentControllerForRoot(aGuid.mLayersId);
+  if (rootController) {
+    MOZ_ASSERT(rootController != this);
+    if (rootController != this) {
+      rootController->NotifyScaleGestureComplete(aGuid, aScale);
+    }
+  }
+}
+
+void RemoteContentController::NotifyScaleGestureCompleteCrossProcess(
+    const ScrollableLayerGuid& aGuid, float aScale) {
+  MOZ_ASSERT(XRE_IsGPUProcess());
+
+  if (!mCompositorThread->IsOnCurrentThread()) {
+    mCompositorThread->Dispatch(NewRunnableMethod<ScrollableLayerGuid, float>(
+        "layers::RemoteContentController::"
+        "NotifyScaleGestureCompleteCrossProcess",
+        this, &RemoteContentController::NotifyScaleGestureCompleteCrossProcess,
+        aGuid, aScale));
+    return;
+  }
+
+  // The raw pointer to APZCTreeManagerParent is ok here because we are on
+  // the compositor thread.
+  if (APZCTreeManagerParent* parent =
+          CompositorBridgeParent::GetApzcTreeManagerParentForRoot(
+              aGuid.mLayersId)) {
+    Unused << parent->SendNotifyScaleGestureComplete(aGuid.mScrollId, aScale);
+  }
+}
+
+void RemoteContentController::ActorDestroy(ActorDestroyReason aWhy) {
+  // This controller could possibly be kept alive longer after this
+  // by a RefPtr, but it is no longer valid to send messages.
+  mCanSend = false;
+}
+
+void RemoteContentController::Destroy() {
+  if (mCanSend) {
+    mCanSend = false;
+    Unused << SendDestroy();
+  }
+}
+
+mozilla::ipc::IPCResult RemoteContentController::RecvDestroy() {
+  // The actor on the other side is about to get destroyed, so let's not
+  // send it any more messages.
+  mCanSend = false;
+  return IPC_OK();
+}
+
+bool RemoteContentController::IsRemote() { return true; }
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/RemoteContentController.h b/gfx/layers/ipc/RemoteContentController.h
new file mode 100644
index 0000000000..7c2ef3789f
--- /dev/null
+++ b/gfx/layers/ipc/RemoteContentController.h
@@ -0,0 +1,126 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_RemoteContentController_h
+#define mozilla_layers_RemoteContentController_h
+
+#include "mozilla/layers/GeckoContentController.h"
+#include "mozilla/layers/PAPZParent.h"
+
+namespace mozilla {
+
+namespace dom {
+class BrowserParent;
+}
+
+namespace layers {
+
+struct DoubleTapToZoomMetrics;
+/**
+ * RemoteContentController implements PAPZChild and is used to access a
+ * GeckoContentController that lives in a different process.
+ *
+ * RemoteContentController lives on the compositor thread. All methods can
+ * be called off the compositor thread and will get dispatched to the right
+ * thread, with the exception of RequestContentRepaint and NotifyFlushComplete,
+ * which must be called on the repaint thread, which in this case is the
+ * compositor thread.
+ */
+class RemoteContentController : public GeckoContentController,
+                                public PAPZParent {
+  using GeckoContentController::APZStateChange;
+  using GeckoContentController::TapType;
+
+ public:
+  RemoteContentController();
+
+  virtual ~RemoteContentController();
+
+  void NotifyLayerTransforms(nsTArray<MatrixMessage>&& aTransforms) override;
+
+  void RequestContentRepaint(const RepaintRequest& aRequest) override;
+
+  void HandleTap(
+      TapType aTapType, const LayoutDevicePoint& aPoint, Modifiers aModifiers,
+      const ScrollableLayerGuid& aGuid, uint64_t aInputBlockId,
+      const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics) override;
+
+  void NotifyPinchGesture(PinchGestureInput::PinchGestureType aType,
+                          const ScrollableLayerGuid& aGuid,
+                          const LayoutDevicePoint& aFocusPoint,
+                          LayoutDeviceCoord aSpanChange,
+                          Modifiers aModifiers) override;
+
+  bool IsRepaintThread() override;
+
+  void DispatchToRepaintThread(already_AddRefed<Runnable> aTask) override;
+
+  void NotifyAPZStateChange(const ScrollableLayerGuid& aGuid,
+                            APZStateChange aChange, int aArg,
+                            Maybe<uint64_t> aInputBlockId) override;
+
+  void UpdateOverscrollVelocity(const ScrollableLayerGuid& aGuid, float aX,
+                                float aY, bool aIsRootContent) override;
+
+  void UpdateOverscrollOffset(const ScrollableLayerGuid& aGuid, float aX,
+                              float aY, bool aIsRootContent) override;
+
+  void NotifyMozMouseScrollEvent(const ScrollableLayerGuid::ViewID& aScrollId,
+                                 const nsString& aEvent) override;
+
+  void NotifyFlushComplete() override;
+
+  void NotifyAsyncScrollbarDragInitiated(
+      uint64_t aDragBlockId, const ScrollableLayerGuid::ViewID& aScrollId,
+      ScrollDirection aDirection) override;
+  void NotifyAsyncScrollbarDragRejected(
+      const ScrollableLayerGuid::ViewID& aScrollId) override;
+
+  void NotifyAsyncAutoscrollRejected(
+      const ScrollableLayerGuid::ViewID& aScrollId) override;
+
+  void CancelAutoscroll(const ScrollableLayerGuid& aScrollId) override;
+
+  void NotifyScaleGestureComplete(const ScrollableLayerGuid& aGuid,
+                                  float aScale) override;
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  void Destroy() override;
+  mozilla::ipc::IPCResult RecvDestroy();
+
+  bool IsRemote() override;
+
+ private:
+  nsCOMPtr<nsISerialEventTarget> mCompositorThread;
+  bool mCanSend;
+
+  void HandleTapOnMainThread(
+      TapType aType, LayoutDevicePoint aPoint, Modifiers aModifiers,
+      ScrollableLayerGuid aGuid, uint64_t aInputBlockId,
+      const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics);
+  void HandleTapOnCompositorThread(
+      TapType aType, LayoutDevicePoint aPoint, Modifiers aModifiers,
+      ScrollableLayerGuid aGuid, uint64_t aInputBlockId,
+      const Maybe<DoubleTapToZoomMetrics>& aDoubleTapToZoomMetrics);
+  void NotifyPinchGestureOnCompositorThread(
+      PinchGestureInput::PinchGestureType aType,
+      const ScrollableLayerGuid& aGuid, const LayoutDevicePoint& aFocusPoint,
+      LayoutDeviceCoord aSpanChange, Modifiers aModifiers);
+
+  void CancelAutoscrollInProcess(const ScrollableLayerGuid& aScrollId);
+  void CancelAutoscrollCrossProcess(const ScrollableLayerGuid& aScrollId);
+  void NotifyScaleGestureCompleteInProcess(const ScrollableLayerGuid& aGuid,
+                                           float aScale);
+  void NotifyScaleGestureCompleteCrossProcess(const ScrollableLayerGuid& aGuid,
+                                              float aScale);
+};
+
+}  // namespace layers
+
+}  // namespace mozilla
+
+#endif  // mozilla_layers_RemoteContentController_h
diff --git a/gfx/layers/ipc/ShadowLayerUtils.h b/gfx/layers/ipc/ShadowLayerUtils.h
new file mode 100644
index 0000000000..de07854b04
--- /dev/null
+++ b/gfx/layers/ipc/ShadowLayerUtils.h
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef IPC_ShadowLayerUtils_h
+#define IPC_ShadowLayerUtils_h
+
+#include "ipc/EnumSerializer.h"
+#include "ipc/IPCMessageUtils.h"
+#include "GLContextTypes.h"
+#include "SurfaceDescriptor.h"
+#include "SurfaceTypes.h"
+#include "mozilla/WidgetUtils.h"
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::ScreenRotation>
+    : public ContiguousEnumSerializer<mozilla::ScreenRotation,
+                                      mozilla::ROTATION_0,
+                                      mozilla::ROTATION_COUNT> {};
+
+}  // namespace IPC
+
+#endif  // IPC_ShadowLayerUtils_h
diff --git a/gfx/layers/ipc/SharedPlanarYCbCrImage.cpp b/gfx/layers/ipc/SharedPlanarYCbCrImage.cpp
new file mode 100644
index 0000000000..0757d1e22b
--- /dev/null
+++ b/gfx/layers/ipc/SharedPlanarYCbCrImage.cpp
@@ -0,0 +1,193 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SharedPlanarYCbCrImage.h"
+#include <stddef.h>                    // for size_t
+#include <stdio.h>                     // for printf
+#include "gfx2DGlue.h"                 // for Moz2D transition helpers
+#include "ISurfaceAllocator.h"         // for ISurfaceAllocator, etc
+#include "mozilla/Assertions.h"        // for MOZ_ASSERT, etc
+#include "mozilla/gfx/Types.h"         // for SurfaceFormat::SurfaceFormat::YUV
+#include "mozilla/ipc/SharedMemory.h"  // for SharedMemory, etc
+#include "mozilla/layers/ImageClient.h"     // for ImageClient
+#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor, etc
+#include "mozilla/layers/TextureClient.h"
+#include "mozilla/layers/TextureClientRecycleAllocator.h"
+#include "mozilla/layers/BufferTexture.h"
+#include "mozilla/layers/ImageDataSerializer.h"
+#include "mozilla/layers/ImageBridgeChild.h"  // for ImageBridgeChild
+#include "mozilla/mozalloc.h"                 // for operator delete
+#include "nsISupportsImpl.h"                  // for Image::AddRef
+#include "mozilla/ipc/Shmem.h"
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::ipc;
+
+SharedPlanarYCbCrImage::SharedPlanarYCbCrImage(ImageClient* aCompositable)
+    : mCompositable(aCompositable) {
+  MOZ_COUNT_CTOR(SharedPlanarYCbCrImage);
+}
+
+SharedPlanarYCbCrImage::SharedPlanarYCbCrImage(
+    TextureClientRecycleAllocator* aRecycleAllocator)
+    : mRecycleAllocator(aRecycleAllocator) {
+  MOZ_COUNT_CTOR(SharedPlanarYCbCrImage);
+}
+
+SharedPlanarYCbCrImage::~SharedPlanarYCbCrImage() {
+  MOZ_COUNT_DTOR(SharedPlanarYCbCrImage);
+}
+
+TextureClientRecycleAllocator* SharedPlanarYCbCrImage::RecycleAllocator() {
+  static const uint32_t MAX_POOLED_VIDEO_COUNT = 5;
+
+  if (!mRecycleAllocator && mCompositable) {
+    if (!mCompositable->HasTextureClientRecycler()) {
+      // Initialize TextureClientRecycler
+      mCompositable->GetTextureClientRecycler()->SetMaxPoolSize(
+          MAX_POOLED_VIDEO_COUNT);
+    }
+    mRecycleAllocator = mCompositable->GetTextureClientRecycler();
+  }
+  return mRecycleAllocator;
+}
+
+size_t SharedPlanarYCbCrImage::SizeOfExcludingThis(
+    MallocSizeOf aMallocSizeOf) const {
+  // NB: Explicitly skipping mTextureClient, the memory is already reported
+  //     at time of allocation in GfxMemoryImageReporter.
+  // Not owned:
+  // - mCompositable
+  return 0;
+}
+
+TextureClient* SharedPlanarYCbCrImage::GetTextureClient(
+    KnowsCompositor* aKnowsCompositor) {
+  return mTextureClient.get();
+}
+
+already_AddRefed<gfx::SourceSurface>
+SharedPlanarYCbCrImage::GetAsSourceSurface() {
+  if (!IsValid()) {
+    NS_WARNING("Can't get as surface");
+    return nullptr;
+  }
+  return PlanarYCbCrImage::GetAsSourceSurface();
+}
+
+nsresult SharedPlanarYCbCrImage::CopyData(const PlanarYCbCrData& aData) {
+  // If mTextureClient has not already been allocated by CreateEmptyBuffer,
+  // allocate it. This code path is slower than the one used when
+  // CreateEmptyBuffer has been called since it will trigger a full copy.
+  if (!mTextureClient) {
+    nsresult r =
+        CreateEmptyBuffer(aData, aData.YDataSize(), aData.CbCrDataSize());
+    if (NS_FAILED(r)) {
+      return r;
+    }
+  }
+
+  TextureClientAutoLock autoLock(mTextureClient, OpenMode::OPEN_WRITE_ONLY);
+  if (!autoLock.Succeeded()) {
+    MOZ_ASSERT(false, "Failed to lock the texture.");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (!UpdateYCbCrTextureClient(mTextureClient, aData)) {
+    MOZ_ASSERT(false, "Failed to copy YCbCr data into the TextureClient");
+    return NS_ERROR_UNEXPECTED;
+  }
+  mTextureClient->MarkImmutable();
+  return NS_OK;
+}
+
+nsresult SharedPlanarYCbCrImage::AdoptData(const Data& aData) {
+  MOZ_ASSERT(false, "This shouldn't be used.");
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
+bool SharedPlanarYCbCrImage::IsValid() const {
+  return mTextureClient && mTextureClient->IsValid();
+}
+
+nsresult SharedPlanarYCbCrImage::CreateEmptyBuffer(
+    const PlanarYCbCrData& aData, const gfx::IntSize& aYSize,
+    const gfx::IntSize& aCbCrSize) {
+  MOZ_ASSERT(!mTextureClient, "This image already has allocated data");
+
+  TextureFlags flags =
+      mCompositable ? mCompositable->GetTextureFlags() : TextureFlags::DEFAULT;
+  {
+    YCbCrTextureClientAllocationHelper helper(aData, aYSize, aCbCrSize, flags);
+    Result<already_AddRefed<TextureClient>, nsresult> result =
+        RecycleAllocator()->CreateOrRecycle(helper);
+    if (result.isErr()) {
+      return Err(result.unwrapErr());
+    }
+    mTextureClient = result.unwrap();
+  }
+
+  if (!mTextureClient) {
+    NS_WARNING("SharedPlanarYCbCrImage::Allocate failed.");
+    // TODO: TextureClientRecycleAllocator::CreateOrRecycle may return NULL on
+    // non out-of-memory failures.
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  MappedYCbCrTextureData mapped;
+  // The locking here is sort of a lie. The SharedPlanarYCbCrImage just pulls
+  // pointers out of the TextureClient and keeps them around, which works only
+  // because the underlyin BufferTextureData is always mapped in memory even
+  // outside of the lock/unlock interval. That's sad and new code should follow
+  // this example.
+  if (!mTextureClient->Lock(OpenMode::OPEN_READ) ||
+      !mTextureClient->BorrowMappedYCbCrData(mapped)) {
+    MOZ_CRASH("GFX: Cannot lock or borrow mapped YCbCr");
+  }
+
+  // copy some of aData's values in mData (most of them)
+  mData.mYChannel = mapped.y.data;
+  mData.mCbChannel = mapped.cb.data;
+  mData.mCrChannel = mapped.cr.data;
+  mData.mPictureRect = aData.mPictureRect;
+  mData.mStereoMode = aData.mStereoMode;
+  mData.mYUVColorSpace = aData.mYUVColorSpace;
+  mData.mColorDepth = aData.mColorDepth;
+  mData.mChromaSubsampling = aData.mChromaSubsampling;
+  // those members are not always equal to aData's, due to potentially different
+  // packing.
+  mData.mYSkip = 0;
+  mData.mCbSkip = 0;
+  mData.mCrSkip = 0;
+  mData.mYStride = aData.mYStride;
+  mData.mCbCrStride = aData.mCbCrStride;
+
+  // do not set mBuffer like in PlanarYCbCrImage because the later
+  // will try to manage this memory without knowing it belongs to a
+  // shmem.
+  mBufferSize = ImageDataSerializer::ComputeYCbCrBufferSize(
+      aYSize, mData.mYStride, aCbCrSize, mData.mCbCrStride);
+  mSize = mData.mPictureRect.Size();
+  mOrigin = mData.mPictureRect.TopLeft();
+
+  mTextureClient->Unlock();
+
+  // ImageDataSerializer::ComputeYCbCrBufferSize may return zero when the size
+  // requested is out of the limit.
+  return mBufferSize > 0 ? NS_OK : NS_ERROR_INVALID_ARG;
+}
+
+void SharedPlanarYCbCrImage::SetIsDRM(bool aIsDRM) {
+  Image::SetIsDRM(aIsDRM);
+  if (mTextureClient) {
+    mTextureClient->AddFlags(TextureFlags::DRM_SOURCE);
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/SharedPlanarYCbCrImage.h b/gfx/layers/ipc/SharedPlanarYCbCrImage.h
new file mode 100644
index 0000000000..9f6c06df55
--- /dev/null
+++ b/gfx/layers/ipc/SharedPlanarYCbCrImage.h
@@ -0,0 +1,64 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdint.h>              // for uint8_t, uint32_t
+#include "ImageContainer.h"      // for PlanarYCbCrImage, etc
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/RefPtr.h"      // for RefPtr
+#include "mozilla/ipc/Shmem.h"   // for Shmem
+#include "nsCOMPtr.h"            // for already_AddRefed
+#include "nsDebug.h"             // for NS_WARNING
+#include "nsISupportsImpl.h"     // for MOZ_COUNT_CTOR
+
+#ifndef MOZILLA_LAYERS_SHAREDPLANARYCBCRIMAGE_H
+#  define MOZILLA_LAYERS_SHAREDPLANARYCBCRIMAGE_H
+
+namespace mozilla {
+namespace layers {
+
+class ImageClient;
+class TextureClient;
+class TextureClientRecycleAllocator;
+
+class SharedPlanarYCbCrImage : public PlanarYCbCrImage {
+ public:
+  explicit SharedPlanarYCbCrImage(ImageClient* aCompositable);
+  explicit SharedPlanarYCbCrImage(
+      TextureClientRecycleAllocator* aRecycleAllocator);
+
+ protected:
+  virtual ~SharedPlanarYCbCrImage();
+
+ public:
+  TextureClient* GetTextureClient(KnowsCompositor* aKnowsCompositor) override;
+
+  already_AddRefed<gfx::SourceSurface> GetAsSourceSurface() override;
+  nsresult CopyData(const PlanarYCbCrData& aData) override;
+  nsresult AdoptData(const Data& aData) override;
+  nsresult CreateEmptyBuffer(const Data& aData, const gfx::IntSize& aYSize,
+                             const gfx::IntSize& aCbCrSize) override;
+
+  void SetIsDRM(bool aIsDRM) override;
+  bool IsValid() const override;
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override;
+
+  TextureClientRecycleAllocator* RecycleAllocator();
+
+ private:
+  RefPtr<TextureClient> mTextureClient;
+  RefPtr<ImageClient> mCompositable;
+  RefPtr<TextureClientRecycleAllocator> mRecycleAllocator;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/SharedRGBImage.cpp b/gfx/layers/ipc/SharedRGBImage.cpp
new file mode 100644
index 0000000000..beb69ec4eb
--- /dev/null
+++ b/gfx/layers/ipc/SharedRGBImage.cpp
@@ -0,0 +1,157 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SharedRGBImage.h"
+#include "ImageTypes.h"         // for ImageFormat::SHARED_RGB, etc
+#include "mozilla/ipc/Shmem.h"  // for Shmem
+#include "gfx2DGlue.h"          // for ImageFormatToSurfaceFormat, etc
+#include "gfxPlatform.h"        // for gfxPlatform, gfxImageFormat
+#include "mozilla/gfx/Point.h"  // for IntSIze
+#include "mozilla/layers/BufferTexture.h"
+#include "mozilla/layers/ISurfaceAllocator.h"  // for ISurfaceAllocator, etc
+#include "mozilla/layers/ImageClient.h"        // for ImageClient
+#include "mozilla/layers/LayersSurfaces.h"     // for SurfaceDescriptor, etc
+#include "mozilla/layers/TextureClient.h"      // for BufferTextureClient, etc
+#include "mozilla/layers/TextureClientRecycleAllocator.h"  // for ITextureClientAllocationHelper
+#include "mozilla/layers/ImageBridgeChild.h"  // for ImageBridgeChild
+#include "mozilla/mozalloc.h"                 // for operator delete, etc
+#include "nsDebug.h"                          // for NS_WARNING, NS_ASSERTION
+#include "nsISupportsImpl.h"                  // for Image::AddRef, etc
+#include "nsProxyRelease.h"
+#include "nsRect.h"  // for mozilla::gfx::IntRect
+
+// Just big enough for a 1080p RGBA32 frame
+#define MAX_FRAME_SIZE (16 * 1024 * 1024)
+
+namespace mozilla {
+namespace layers {
+
+class TextureClientForRawBufferAccessAllocationHelper
+    : public ITextureClientAllocationHelper {
+ public:
+  TextureClientForRawBufferAccessAllocationHelper(gfx::SurfaceFormat aFormat,
+                                                  gfx::IntSize aSize,
+                                                  TextureFlags aTextureFlags)
+      : ITextureClientAllocationHelper(aFormat, aSize, BackendSelector::Content,
+                                       aTextureFlags, ALLOC_DEFAULT) {}
+
+  bool IsCompatible(TextureClient* aTextureClient) override {
+    bool ret = aTextureClient->GetFormat() == mFormat &&
+               aTextureClient->GetSize() == mSize;
+    return ret;
+  }
+
+  already_AddRefed<TextureClient> Allocate(
+      KnowsCompositor* aAllocator) override {
+    return TextureClient::CreateForRawBufferAccess(
+        aAllocator, mFormat, mSize, gfx::BackendType::NONE, mTextureFlags);
+  }
+};
+
+SharedRGBImage::SharedRGBImage(ImageClient* aCompositable)
+    : Image(nullptr, ImageFormat::SHARED_RGB), mCompositable(aCompositable) {
+  MOZ_COUNT_CTOR(SharedRGBImage);
+}
+
+SharedRGBImage::SharedRGBImage(TextureClientRecycleAllocator* aRecycleAllocator)
+    : Image(nullptr, ImageFormat::SHARED_RGB),
+      mRecycleAllocator(aRecycleAllocator) {
+  MOZ_COUNT_CTOR(SharedRGBImage);
+}
+
+SharedRGBImage::~SharedRGBImage() {
+  MOZ_COUNT_DTOR(SharedRGBImage);
+  NS_ReleaseOnMainThread("SharedRGBImage::mSourceSurface",
+                         mSourceSurface.forget());
+}
+
+TextureClientRecycleAllocator* SharedRGBImage::RecycleAllocator() {
+  static const uint32_t MAX_POOLED_VIDEO_COUNT = 5;
+
+  if (!mRecycleAllocator && mCompositable) {
+    if (!mCompositable->HasTextureClientRecycler()) {
+      // Initialize TextureClientRecycler
+      mCompositable->GetTextureClientRecycler()->SetMaxPoolSize(
+          MAX_POOLED_VIDEO_COUNT);
+    }
+    mRecycleAllocator = mCompositable->GetTextureClientRecycler();
+  }
+  return mRecycleAllocator;
+}
+
+bool SharedRGBImage::Allocate(gfx::IntSize aSize, gfx::SurfaceFormat aFormat) {
+  mSize = aSize;
+
+  TextureFlags flags =
+      mCompositable ? mCompositable->GetTextureFlags() : TextureFlags::DEFAULT;
+  {
+    TextureClientForRawBufferAccessAllocationHelper helper(aFormat, aSize,
+                                                           flags);
+    mTextureClient =
+        RecycleAllocator()->CreateOrRecycle(helper).unwrapOr(nullptr);
+  }
+
+  return !!mTextureClient;
+}
+
+gfx::IntSize SharedRGBImage::GetSize() const { return mSize; }
+
+TextureClient* SharedRGBImage::GetTextureClient(
+    KnowsCompositor* aKnowsCompositor) {
+  return mTextureClient.get();
+}
+
+static void ReleaseTextureClient(void* aData) {
+  RELEASE_MANUALLY(static_cast<TextureClient*>(aData));
+}
+
+static gfx::UserDataKey sTextureClientKey;
+
+already_AddRefed<gfx::SourceSurface> SharedRGBImage::GetAsSourceSurface() {
+  NS_ASSERTION(NS_IsMainThread(), "Must be main thread");
+
+  if (mSourceSurface) {
+    RefPtr<gfx::SourceSurface> surface(mSourceSurface);
+    return surface.forget();
+  }
+
+  RefPtr<gfx::SourceSurface> surface;
+  {
+    // We are 'borrowing' the DrawTarget and retaining a permanent reference to
+    // the underlying data (via the surface). It is in this instance since we
+    // know that the TextureClient is always wrapping a BufferTextureData and
+    // therefore it won't go away underneath us.
+    BufferTextureData* decoded_buffer =
+        mTextureClient->GetInternalData()->AsBufferTextureData();
+    RefPtr<gfx::DrawTarget> drawTarget = decoded_buffer->BorrowDrawTarget();
+
+    if (!drawTarget) {
+      return nullptr;
+    }
+
+    surface = drawTarget->Snapshot();
+    if (!surface) {
+      return nullptr;
+    }
+
+    // The surface may outlive the owning TextureClient. So, we need to ensure
+    // that the surface keeps the TextureClient alive via a reference held in
+    // user data. The TextureClient's DrawTarget only has a weak reference to
+    // the surface, so we won't create any cycles by just referencing the
+    // TextureClient.
+    if (!surface->GetUserData(&sTextureClientKey)) {
+      surface->AddUserData(&sTextureClientKey, mTextureClient,
+                           ReleaseTextureClient);
+      ADDREF_MANUALLY(mTextureClient);
+    }
+  }
+
+  mSourceSurface = surface;
+  return surface.forget();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/SharedRGBImage.h b/gfx/layers/ipc/SharedRGBImage.h
new file mode 100644
index 0000000000..ddec2dc9aa
--- /dev/null
+++ b/gfx/layers/ipc/SharedRGBImage.h
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef SHAREDRGBIMAGE_H_
+#define SHAREDRGBIMAGE_H_
+
+#include <stddef.h>  // for size_t
+#include <stdint.h>  // for uint8_t
+
+#include "ImageContainer.h"  // for ISharedImage, Image, etc
+#include "gfxTypes.h"
+#include "mozilla/Attributes.h"  // for override
+#include "mozilla/RefPtr.h"      // for RefPtr
+#include "mozilla/gfx/Point.h"   // for IntSize
+#include "mozilla/gfx/Types.h"   // for SurfaceFormat
+#include "nsCOMPtr.h"            // for already_AddRefed
+
+namespace mozilla {
+namespace layers {
+
+class ImageClient;
+class TextureClient;
+
+/**
+ * Stores RGB data in shared memory
+ * It is assumed that the image width and stride are equal
+ */
+class SharedRGBImage : public Image {
+ public:
+  explicit SharedRGBImage(ImageClient* aCompositable);
+  explicit SharedRGBImage(TextureClientRecycleAllocator* aRecycleAllocator);
+
+ protected:
+  virtual ~SharedRGBImage();
+
+ public:
+  TextureClient* GetTextureClient(KnowsCompositor* aKnowsCompositor) override;
+
+  gfx::IntSize GetSize() const override;
+
+  already_AddRefed<gfx::SourceSurface> GetAsSourceSurface() override;
+
+  bool Allocate(gfx::IntSize aSize, gfx::SurfaceFormat aFormat);
+
+ private:
+  TextureClientRecycleAllocator* RecycleAllocator();
+
+  gfx::IntSize mSize;
+  RefPtr<TextureClient> mTextureClient;
+  RefPtr<ImageClient> mCompositable;
+  RefPtr<TextureClientRecycleAllocator> mRecycleAllocator;
+  RefPtr<gfx::SourceSurface> mSourceSurface;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/SharedSurfacesChild.cpp b/gfx/layers/ipc/SharedSurfacesChild.cpp
new file mode 100644
index 0000000000..0f8b2a9743
--- /dev/null
+++ b/gfx/layers/ipc/SharedSurfacesChild.cpp
@@ -0,0 +1,656 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SharedSurfacesChild.h"
+#include "CompositorManagerChild.h"
+#include "mozilla/layers/IpcResourceUpdateQueue.h"
+#include "mozilla/layers/SourceSurfaceSharedData.h"
+#include "mozilla/layers/WebRenderBridgeChild.h"
+#include "mozilla/layers/RenderRootStateManager.h"
+#include "mozilla/layers/WebRenderLayerManager.h"
+#include "mozilla/layers/CompositorBridgeChild.h"
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/SchedulerGroup.h"
+#include "mozilla/StaticPrefs_image.h"
+#include "mozilla/PresShell.h"
+#include "nsRefreshDriver.h"
+#include "nsView.h"
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::gfx;
+
+/* static */
+UserDataKey SharedSurfacesChild::sSharedKey;
+
+SharedSurfacesChild::ImageKeyData::ImageKeyData(
+    RenderRootStateManager* aManager, const wr::ImageKey& aImageKey)
+    : mManager(aManager), mImageKey(aImageKey) {}
+
+SharedSurfacesChild::ImageKeyData::ImageKeyData(
+    SharedSurfacesChild::ImageKeyData&& aOther)
+    : mManager(std::move(aOther.mManager)),
+      mDirtyRect(std::move(aOther.mDirtyRect)),
+      mImageKey(aOther.mImageKey) {}
+
+SharedSurfacesChild::ImageKeyData& SharedSurfacesChild::ImageKeyData::operator=(
+    SharedSurfacesChild::ImageKeyData&& aOther) {
+  mManager = std::move(aOther.mManager);
+  mDirtyRect = std::move(aOther.mDirtyRect);
+  mImageKey = aOther.mImageKey;
+  return *this;
+}
+
+SharedSurfacesChild::ImageKeyData::~ImageKeyData() = default;
+
+void SharedSurfacesChild::ImageKeyData::MergeDirtyRect(
+    const Maybe<IntRect>& aDirtyRect) {
+  if (mDirtyRect) {
+    if (aDirtyRect) {
+      mDirtyRect->UnionRect(mDirtyRect.ref(), aDirtyRect.ref());
+    }
+  } else {
+    mDirtyRect = aDirtyRect;
+  }
+}
+
+SharedSurfacesChild::SharedUserData::SharedUserData()
+    : Runnable("SharedSurfacesChild::SharedUserData"),
+      mId({}),
+      mShared(false) {}
+
+SharedSurfacesChild::SharedUserData::~SharedUserData() {
+  // We may fail to dispatch during shutdown, and since it would be issued on
+  // the main thread, it releases the runnable instead of leaking it.
+  if (mShared || !mKeys.IsEmpty()) {
+    if (NS_IsMainThread()) {
+      SharedSurfacesChild::Unshare(mId, mShared, mKeys);
+    } else {
+      MOZ_ASSERT_UNREACHABLE("Shared resources not released!");
+    }
+  }
+}
+
+/* static */
+void SharedSurfacesChild::SharedUserData::Destroy(void* aClosure) {
+  MOZ_ASSERT(aClosure);
+  RefPtr<SharedUserData> data =
+      dont_AddRef(static_cast<SharedUserData*>(aClosure));
+  if (data->mShared || !data->mKeys.IsEmpty()) {
+    SchedulerGroup::Dispatch(data.forget());
+  }
+}
+
+NS_IMETHODIMP SharedSurfacesChild::SharedUserData::Run() {
+  SharedSurfacesChild::Unshare(mId, mShared, mKeys);
+  mShared = false;
+  mKeys.Clear();
+  return NS_OK;
+}
+
+wr::ImageKey SharedSurfacesChild::SharedUserData::UpdateKey(
+    RenderRootStateManager* aManager, wr::IpcResourceUpdateQueue& aResources,
+    const Maybe<IntRect>& aDirtyRect) {
+  MOZ_ASSERT(aManager);
+  MOZ_ASSERT(!aManager->IsDestroyed());
+
+  // We iterate through all of the items to ensure we clean up the old
+  // RenderRootStateManager references. Most of the time there will be few
+  // entries and this should not be particularly expensive compared to the
+  // cost of duplicating image keys. In an ideal world, we would generate a
+  // single key for the surface, and it would be usable on all of the
+  // renderer instances. For now, we must allocate a key for each WR bridge.
+  wr::ImageKey key;
+  bool found = false;
+  auto i = mKeys.Length();
+  while (i > 0) {
+    --i;
+    ImageKeyData& entry = mKeys[i];
+    if (entry.mManager->IsDestroyed()) {
+      mKeys.RemoveElementAt(i);
+    } else if (entry.mManager == aManager) {
+      WebRenderBridgeChild* wrBridge = aManager->WrBridge();
+      MOZ_ASSERT(wrBridge);
+
+      // Even if the manager is the same, its underlying WebRenderBridgeChild
+      // can change state. If our namespace differs, then our old key has
+      // already been discarded.
+      bool ownsKey = wrBridge->GetNamespace() == entry.mImageKey.mNamespace;
+      if (!ownsKey) {
+        entry.mImageKey = wrBridge->GetNextImageKey();
+        entry.TakeDirtyRect();
+        aResources.AddSharedExternalImage(mId, entry.mImageKey);
+      } else {
+        entry.MergeDirtyRect(aDirtyRect);
+        Maybe<IntRect> dirtyRect = entry.TakeDirtyRect();
+        if (dirtyRect) {
+          MOZ_ASSERT(mShared);
+          aResources.UpdateSharedExternalImage(
+              mId, entry.mImageKey, ViewAs<ImagePixel>(dirtyRect.ref()));
+        }
+      }
+
+      key = entry.mImageKey;
+      found = true;
+    } else {
+      // We don't have the resource update queue for this manager, so just
+      // accumulate the dirty rects until it is requested.
+      entry.MergeDirtyRect(aDirtyRect);
+    }
+  }
+
+  if (!found) {
+    key = aManager->WrBridge()->GetNextImageKey();
+    ImageKeyData data(aManager, key);
+    mKeys.AppendElement(std::move(data));
+    aResources.AddSharedExternalImage(mId, key);
+  }
+
+  return key;
+}
+
+/* static */
+SourceSurfaceSharedData* SharedSurfacesChild::AsSourceSurfaceSharedData(
+    SourceSurface* aSurface) {
+  MOZ_ASSERT(aSurface);
+  switch (aSurface->GetType()) {
+    case SurfaceType::DATA_SHARED:
+    case SurfaceType::DATA_RECYCLING_SHARED:
+      return static_cast<SourceSurfaceSharedData*>(aSurface);
+    default:
+      return nullptr;
+  }
+}
+
+/* static */
+nsresult SharedSurfacesChild::ShareInternal(SourceSurfaceSharedData* aSurface,
+                                            SharedUserData** aUserData) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aSurface);
+  MOZ_ASSERT(aUserData);
+
+  CompositorManagerChild* manager = CompositorManagerChild::GetInstance();
+  if (NS_WARN_IF(!manager || !manager->CanSend())) {
+    // We cannot try to share the surface, most likely because the GPU process
+    // crashed. Ideally, we would retry when it is ready, but the handles may be
+    // a scarce resource, which can cause much more serious problems if we run
+    // out. Better to copy into a fresh buffer later.
+    aSurface->FinishedSharing();
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  SharedUserData* data =
+      static_cast<SharedUserData*>(aSurface->GetUserData(&sSharedKey));
+  if (!data) {
+    data = MakeAndAddRef<SharedUserData>().take();
+    aSurface->AddUserData(&sSharedKey, data, SharedUserData::Destroy);
+  } else if (data->IsShared()) {
+    if (manager->OwnsExternalImageId(data->Id())) {
+      // It has already been shared with the GPU process.
+      *aUserData = data;
+      return NS_OK;
+    }
+
+    // If the id isn't owned by us, that means the bridge was reinitialized, due
+    // to the GPU process crashing. All previous mappings have been released.
+    data->ClearShared();
+  }
+
+  // Ensure that the handle doesn't get released until after we have finished
+  // sending the buffer to the GPU process and/or reallocating it.
+  // FinishedSharing is not a sufficient condition because another thread may
+  // decide we are done while we are in the processing of sharing our newly
+  // reallocated handle. Once it goes out of scope, it may release the handle.
+  SourceSurfaceSharedData::HandleLock lock(aSurface);
+
+  // If we live in the same process, then it is a simple matter of directly
+  // asking the parent instance to store a pointer to the same data, no need
+  // to map the data into our memory space twice.
+  if (manager->SameProcess()) {
+    data->MarkShared(manager->GetNextExternalImageId());
+    CompositorManagerParent::AddSharedSurface(data->Id(), aSurface);
+    *aUserData = data;
+    return NS_OK;
+  }
+
+  // Attempt to share a handle with the GPU process. The handle may or may not
+  // be available -- it will only be available if it is either not yet finalized
+  // and/or if it has been finalized but never used for drawing in process.
+  ipc::SharedMemoryBasic::Handle handle = ipc::SharedMemoryBasic::NULLHandle();
+  nsresult rv = aSurface->CloneHandle(handle);
+  if (rv == NS_ERROR_NOT_AVAILABLE) {
+    // It is at least as expensive to copy the image to the GPU process if we
+    // have already closed the handle necessary to share, but if we reallocate
+    // the shared buffer to get a new handle, we can save some memory.
+    if (NS_WARN_IF(!aSurface->ReallocHandle())) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    // Reattempt the sharing of the handle to the GPU process.
+    rv = aSurface->CloneHandle(handle);
+  }
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    MOZ_ASSERT(rv != NS_ERROR_NOT_AVAILABLE);
+    return rv;
+  }
+
+  SurfaceFormat format = aSurface->GetFormat();
+  MOZ_RELEASE_ASSERT(
+      format == SurfaceFormat::B8G8R8X8 || format == SurfaceFormat::B8G8R8A8,
+      "bad format");
+
+  data->MarkShared(manager->GetNextExternalImageId());
+  manager->SendAddSharedSurface(
+      data->Id(),
+      SurfaceDescriptorShared(aSurface->GetSize(), aSurface->Stride(), format,
+                              std::move(handle)));
+  *aUserData = data;
+  return NS_OK;
+}
+
+/* static */
+void SharedSurfacesChild::Share(SourceSurfaceSharedData* aSurface) {
+  MOZ_ASSERT(aSurface);
+
+  // The IPDL actor to do sharing can only be accessed on the main thread so we
+  // need to dispatch if off the main thread. However there is no real danger if
+  // we end up racing because if it is already shared, this method will do
+  // nothing.
+  if (!NS_IsMainThread()) {
+    class ShareRunnable final : public Runnable {
+     public:
+      explicit ShareRunnable(SourceSurfaceSharedData* aSurface)
+          : Runnable("SharedSurfacesChild::Share"), mSurface(aSurface) {}
+
+      NS_IMETHOD Run() override {
+        SharedUserData* unused = nullptr;
+        SharedSurfacesChild::ShareInternal(mSurface, &unused);
+        return NS_OK;
+      }
+
+     private:
+      RefPtr<SourceSurfaceSharedData> mSurface;
+    };
+
+    SchedulerGroup::Dispatch(MakeAndAddRef<ShareRunnable>(aSurface));
+    return;
+  }
+
+  SharedUserData* unused = nullptr;
+  SharedSurfacesChild::ShareInternal(aSurface, &unused);
+}
+
+/* static */
+nsresult SharedSurfacesChild::Share(SourceSurfaceSharedData* aSurface,
+                                    RenderRootStateManager* aManager,
+                                    wr::IpcResourceUpdateQueue& aResources,
+                                    wr::ImageKey& aKey) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aSurface);
+  MOZ_ASSERT(aManager);
+
+  // Each time the surface changes, the producers of SourceSurfaceSharedData
+  // surfaces promise to increment the invalidation counter each time the
+  // surface has changed. We can use this counter to determine whether or not
+  // we should update our paired ImageKey.
+  Maybe<IntRect> dirtyRect = aSurface->TakeDirtyRect();
+  SharedUserData* data = nullptr;
+  nsresult rv = SharedSurfacesChild::ShareInternal(aSurface, &data);
+  if (NS_SUCCEEDED(rv)) {
+    MOZ_ASSERT(data);
+    aKey = data->UpdateKey(aManager, aResources, dirtyRect);
+  }
+
+  return rv;
+}
+
+/* static */
+nsresult SharedSurfacesChild::Share(SourceSurface* aSurface,
+                                    RenderRootStateManager* aManager,
+                                    wr::IpcResourceUpdateQueue& aResources,
+                                    wr::ImageKey& aKey) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aSurface);
+  MOZ_ASSERT(aManager);
+
+  auto sharedSurface = AsSourceSurfaceSharedData(aSurface);
+  if (!sharedSurface) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  return Share(sharedSurface, aManager, aResources, aKey);
+}
+
+/* static */
+nsresult SharedSurfacesChild::Share(SourceSurface* aSurface,
+                                    wr::ExternalImageId& aId) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aSurface);
+
+  auto sharedSurface = AsSourceSurfaceSharedData(aSurface);
+  if (!sharedSurface) {
+    return NS_ERROR_NOT_IMPLEMENTED;
+  }
+
+  // The external image ID does not change with the invalidation counter. The
+  // caller of this should be aware of the invalidations of the surface through
+  // another mechanism (e.g. imgRequestProxy listener notifications).
+  SharedUserData* data = nullptr;
+  nsresult rv = ShareInternal(sharedSurface, &data);
+  if (NS_SUCCEEDED(rv)) {
+    MOZ_ASSERT(data);
+    aId = data->Id();
+  }
+
+  return rv;
+}
+
+/* static */ nsresult SharedSurfacesChild::Share(
+    gfx::SourceSurface* aSurface, Maybe<SurfaceDescriptor>& aDesc) {
+  if (!aSurface) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  // TODO(aosmond): With a refactor of how we store the external image ID, we
+  // could probably make it safe to access off the main thread. This would be
+  // useful for OffscreenCanvas on DOM workers.
+  if (!NS_IsMainThread()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  wr::ExternalImageId extId{};
+  nsresult rv = Share(aSurface, extId);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  aDesc = Some(SurfaceDescriptorExternalImage(
+      wr::ExternalImageSource::SharedSurfaces, extId));
+  return NS_OK;
+}
+
+/* static */
+void SharedSurfacesChild::Unshare(const wr::ExternalImageId& aId,
+                                  bool aReleaseId,
+                                  nsTArray<ImageKeyData>& aKeys) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  for (const auto& entry : aKeys) {
+    if (!entry.mManager->IsDestroyed()) {
+      entry.mManager->AddImageKeyForDiscard(entry.mImageKey);
+    }
+  }
+
+  if (!aReleaseId) {
+    // We don't own the external image ID itself.
+    return;
+  }
+
+  CompositorManagerChild* manager = CompositorManagerChild::GetInstance();
+  if (MOZ_UNLIKELY(!manager || !manager->CanSend())) {
+    return;
+  }
+
+  if (manager->OwnsExternalImageId(aId)) {
+    // Only attempt to release current mappings in the compositor process. It is
+    // possible we had a surface that was previously shared, the compositor
+    // process crashed / was restarted, and then we freed the surface. In that
+    // case we know the mapping has already been freed.
+    manager->SendRemoveSharedSurface(aId);
+  }
+}
+
+/* static */ Maybe<wr::ExternalImageId> SharedSurfacesChild::GetExternalId(
+    const SourceSurfaceSharedData* aSurface) {
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(aSurface);
+
+  SharedUserData* data =
+      static_cast<SharedUserData*>(aSurface->GetUserData(&sSharedKey));
+  if (!data || !data->IsShared()) {
+    return Nothing();
+  }
+
+  return Some(data->Id());
+}
+
+AnimationImageKeyData::AnimationImageKeyData(RenderRootStateManager* aManager,
+                                             const wr::ImageKey& aImageKey)
+    : SharedSurfacesChild::ImageKeyData(aManager, aImageKey) {}
+
+AnimationImageKeyData::AnimationImageKeyData(AnimationImageKeyData&& aOther)
+    : SharedSurfacesChild::ImageKeyData(std::move(aOther)),
+      mPendingRelease(std::move(aOther.mPendingRelease)) {}
+
+AnimationImageKeyData& AnimationImageKeyData::operator=(
+    AnimationImageKeyData&& aOther) {
+  mPendingRelease = std::move(aOther.mPendingRelease);
+  SharedSurfacesChild::ImageKeyData::operator=(std::move(aOther));
+  return *this;
+}
+
+AnimationImageKeyData::~AnimationImageKeyData() = default;
+
+SharedSurfacesAnimation::~SharedSurfacesAnimation() {
+  MOZ_ASSERT(mKeys.IsEmpty());
+}
+
+void SharedSurfacesAnimation::Destroy() {
+  if (!NS_IsMainThread()) {
+    nsCOMPtr<nsIRunnable> task =
+        NewRunnableMethod("SharedSurfacesAnimation::Destroy", this,
+                          &SharedSurfacesAnimation::Destroy);
+    NS_DispatchToMainThread(task.forget());
+    return;
+  }
+
+  if (mKeys.IsEmpty()) {
+    return;
+  }
+
+  for (const auto& entry : mKeys) {
+    MOZ_ASSERT(!entry.mManager->IsDestroyed());
+    if (StaticPrefs::image_animated_decode_on_demand_recycle_AtStartup()) {
+      entry.mManager->DeregisterAsyncAnimation(entry.mImageKey);
+    }
+    entry.mManager->AddImageKeyForDiscard(entry.mImageKey);
+  }
+
+  mKeys.Clear();
+}
+
+void SharedSurfacesAnimation::HoldSurfaceForRecycling(
+    AnimationImageKeyData& aEntry, SourceSurfaceSharedData* aSurface) {
+  if (aSurface->GetType() != SurfaceType::DATA_RECYCLING_SHARED) {
+    return;
+  }
+
+  MOZ_ASSERT(StaticPrefs::image_animated_decode_on_demand_recycle_AtStartup());
+  aEntry.mPendingRelease.AppendElement(aSurface);
+}
+
+// This will get the widget listener that handles painting. Generally, this is
+// the attached widget listener (or previously attached if the attached is paint
+// suppressed). Otherwise it is the widget listener. There should be a function
+// in nsIWidget that does this for us but there isn't yet.
+static nsIWidgetListener* GetPaintWidgetListener(nsIWidget* aWidget) {
+  if (auto* attached = aWidget->GetAttachedWidgetListener()) {
+    if (attached->GetView() &&
+        attached->GetView()->IsPrimaryFramePaintSuppressed()) {
+      if (auto* previouslyAttached =
+              aWidget->GetPreviouslyAttachedWidgetListener()) {
+        return previouslyAttached;
+      }
+    }
+    return attached;
+  }
+
+  return aWidget->GetWidgetListener();
+}
+
+nsresult SharedSurfacesAnimation::SetCurrentFrame(
+    SourceSurfaceSharedData* aSurface, const gfx::IntRect& aDirtyRect) {
+  MOZ_ASSERT(aSurface);
+
+  SharedSurfacesChild::SharedUserData* data = nullptr;
+  nsresult rv = SharedSurfacesChild::ShareInternal(aSurface, &data);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  MOZ_ASSERT(data);
+  mId = data->Id();
+
+  auto i = mKeys.Length();
+  while (i > 0) {
+    --i;
+    AnimationImageKeyData& entry = mKeys[i];
+    MOZ_ASSERT(!entry.mManager->IsDestroyed());
+
+    if (auto* cbc =
+            entry.mManager->LayerManager()->GetCompositorBridgeChild()) {
+      if (cbc->IsPaused()) {
+        continue;
+      }
+    }
+
+    // Only root compositor bridge childs record if they are paused, so check
+    // the refresh driver.
+    if (auto* widget = entry.mManager->LayerManager()->GetWidget()) {
+      nsIWidgetListener* wl = GetPaintWidgetListener(widget);
+      // Note call to wl->GetView() to make sure this is view type widget
+      // listener even though we don't use the view in this code.
+      if (wl && wl->GetView() && wl->GetPresShell()) {
+        if (auto* rd = wl->GetPresShell()->GetRefreshDriver()) {
+          if (rd->IsThrottled()) {
+            continue;
+          }
+        }
+      }
+    }
+
+    entry.MergeDirtyRect(Some(aDirtyRect));
+    Maybe<IntRect> dirtyRect = entry.TakeDirtyRect();
+    if (dirtyRect) {
+      HoldSurfaceForRecycling(entry, aSurface);
+      auto& resourceUpdates = entry.mManager->AsyncResourceUpdates();
+      resourceUpdates.UpdateSharedExternalImage(
+          mId, entry.mImageKey, ViewAs<ImagePixel>(dirtyRect.ref()));
+    }
+  }
+
+  return NS_OK;
+}
+
+nsresult SharedSurfacesAnimation::UpdateKey(
+    SourceSurfaceSharedData* aSurface, RenderRootStateManager* aManager,
+    wr::IpcResourceUpdateQueue& aResources, wr::ImageKey& aKey) {
+  SharedSurfacesChild::SharedUserData* data = nullptr;
+  nsresult rv = SharedSurfacesChild::ShareInternal(aSurface, &data);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  MOZ_ASSERT(data);
+  if (wr::AsUint64(mId) != wr::AsUint64(data->Id())) {
+    mKeys.Clear();
+    mId = data->Id();
+  }
+
+  // We iterate through all of the items to ensure we clean up the old
+  // RenderRootStateManager references. Most of the time there will be few
+  // entries and this should not be particularly expensive compared to the
+  // cost of duplicating image keys. In an ideal world, we would generate a
+  // single key for the surface, and it would be usable on all of the
+  // renderer instances. For now, we must allocate a key for each WR bridge.
+  bool found = false;
+  auto i = mKeys.Length();
+  while (i > 0) {
+    --i;
+    AnimationImageKeyData& entry = mKeys[i];
+    MOZ_ASSERT(!entry.mManager->IsDestroyed());
+    if (entry.mManager == aManager) {
+      WebRenderBridgeChild* wrBridge = aManager->WrBridge();
+      MOZ_ASSERT(wrBridge);
+
+      // Even if the manager is the same, its underlying WebRenderBridgeChild
+      // can change state. If our namespace differs, then our old key has
+      // already been discarded.
+      bool ownsKey = wrBridge->GetNamespace() == entry.mImageKey.mNamespace;
+      if (!ownsKey) {
+        entry.mImageKey = wrBridge->GetNextImageKey();
+        HoldSurfaceForRecycling(entry, aSurface);
+        aResources.AddSharedExternalImage(mId, entry.mImageKey);
+      } else {
+        MOZ_ASSERT(entry.mDirtyRect.isNothing());
+      }
+
+      aKey = entry.mImageKey;
+      found = true;
+      break;
+    }
+  }
+
+  if (!found) {
+    aKey = aManager->WrBridge()->GetNextImageKey();
+    if (StaticPrefs::image_animated_decode_on_demand_recycle_AtStartup()) {
+      aManager->RegisterAsyncAnimation(aKey, this);
+    }
+
+    AnimationImageKeyData data(aManager, aKey);
+    HoldSurfaceForRecycling(data, aSurface);
+    mKeys.AppendElement(std::move(data));
+    aResources.AddSharedExternalImage(mId, aKey);
+  }
+
+  return NS_OK;
+}
+
+void SharedSurfacesAnimation::ReleasePreviousFrame(
+    RenderRootStateManager* aManager, const wr::ExternalImageId& aId) {
+  MOZ_ASSERT(aManager);
+
+  auto i = mKeys.Length();
+  while (i > 0) {
+    --i;
+    AnimationImageKeyData& entry = mKeys[i];
+    MOZ_ASSERT(!entry.mManager->IsDestroyed());
+    if (entry.mManager == aManager) {
+      size_t k;
+      for (k = 0; k < entry.mPendingRelease.Length(); ++k) {
+        Maybe<wr::ExternalImageId> extId =
+            SharedSurfacesChild::GetExternalId(entry.mPendingRelease[k]);
+        if (extId && extId.ref() == aId) {
+          break;
+        }
+      }
+
+      if (k == entry.mPendingRelease.Length()) {
+        continue;
+      }
+
+      entry.mPendingRelease.RemoveElementsAt(0, k + 1);
+      break;
+    }
+  }
+}
+
+void SharedSurfacesAnimation::Invalidate(RenderRootStateManager* aManager) {
+  auto i = mKeys.Length();
+  while (i > 0) {
+    --i;
+    AnimationImageKeyData& entry = mKeys[i];
+    if (entry.mManager == aManager) {
+      mKeys.RemoveElementAt(i);
+      break;
+    }
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/SharedSurfacesChild.h b/gfx/layers/ipc/SharedSurfacesChild.h
new file mode 100644
index 0000000000..02e2d6aafe
--- /dev/null
+++ b/gfx/layers/ipc/SharedSurfacesChild.h
@@ -0,0 +1,259 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_SHAREDSURFACESCHILD_H
+#define MOZILLA_GFX_SHAREDSURFACESCHILD_H
+
+#include <stdint.h>                            // for uint32_t, uint64_t
+#include "mozilla/Attributes.h"                // for override
+#include "mozilla/Maybe.h"                     // for Maybe
+#include "mozilla/RefPtr.h"                    // for already_AddRefed
+#include "mozilla/StaticPtr.h"                 // for StaticRefPtr
+#include "mozilla/gfx/UserData.h"              // for UserDataKey
+#include "mozilla/layers/LayersSurfaces.h"     // for SurfaceDescriptor
+#include "mozilla/webrender/WebRenderTypes.h"  // for wr::ImageKey
+#include "nsTArray.h"                          // for AutoTArray
+#include "nsThreadUtils.h"                     // for Runnable
+#include "ImageTypes.h"                        // for ContainerProducerID
+
+namespace mozilla {
+namespace layers {
+class AnimationImageKeyData;
+}  // namespace layers
+}  // namespace mozilla
+
+template <>
+struct nsTArray_RelocationStrategy<mozilla::layers::AnimationImageKeyData> {
+  typedef nsTArray_RelocateUsingMoveConstructor<
+      mozilla::layers::AnimationImageKeyData>
+      Type;
+};
+
+namespace mozilla {
+namespace gfx {
+class SourceSurface;
+class SourceSurfaceSharedData;
+}  // namespace gfx
+
+namespace wr {
+class IpcResourceUpdateQueue;
+}  // namespace wr
+
+namespace layers {
+
+class CompositorManagerChild;
+class RenderRootStateManager;
+
+class SharedSurfacesChild {
+ public:
+  /**
+   * Request that the surface be mapped into the compositor thread's memory
+   * space. This is useful for when the caller itself has no present need for
+   * the surface to be mapped, but knows there will be such a need in the
+   * future. This may be called from any thread, but it may cause a dispatch to
+   * the main thread.
+   */
+  static void Share(gfx::SourceSurfaceSharedData* aSurface);
+
+  /**
+   * Request that the surface be mapped into the compositor thread's memory
+   * space, and a valid ExternalImageId be generated for it for use with
+   * WebRender. This must be called from the main thread.
+   */
+  static nsresult Share(gfx::SourceSurface* aSurface, wr::ExternalImageId& aId);
+
+  /**
+   * Request that the surface be mapped into the compositor thread's memory
+   * space, and a valid ExternalImageId be generated for it for use with
+   * WebRender. This must be called from the main thread.
+   */
+  static nsresult Share(gfx::SourceSurface* aSurface,
+                        Maybe<SurfaceDescriptor>& aDesc);
+
+  /**
+   * Request that the surface be mapped into the compositor thread's memory
+   * space, and a valid ImageKey be generated for it for use with WebRender.
+   * This must be called from the main thread.
+   */
+  static nsresult Share(gfx::SourceSurfaceSharedData* aSurface,
+                        RenderRootStateManager* aManager,
+                        wr::IpcResourceUpdateQueue& aResources,
+                        wr::ImageKey& aKey);
+
+  /**
+   * Request that the surface be mapped into the compositor thread's memory
+   * space, and a valid ImageKey be generated for it for use with WebRender.
+   * This must be called from the main thread.
+   */
+  static nsresult Share(gfx::SourceSurface* aSurface,
+                        RenderRootStateManager* aManager,
+                        wr::IpcResourceUpdateQueue& aResources,
+                        wr::ImageKey& aKey);
+
+  /**
+   * Get the external ID, if any, bound to the shared surface. Used for memory
+   * reporting purposes.
+   */
+  static Maybe<wr::ExternalImageId> GetExternalId(
+      const gfx::SourceSurfaceSharedData* aSurface);
+
+  /**
+   * Get the surface (or its underlying surface) as a SourceSurfaceSharedData
+   * pointer, if valid.
+   */
+  static gfx::SourceSurfaceSharedData* AsSourceSurfaceSharedData(
+      gfx::SourceSurface* aSurface);
+
+  class ImageKeyData {
+   public:
+    ImageKeyData(RenderRootStateManager* aManager,
+                 const wr::ImageKey& aImageKey);
+    virtual ~ImageKeyData();
+
+    ImageKeyData(ImageKeyData&& aOther);
+    ImageKeyData& operator=(ImageKeyData&& aOther);
+    ImageKeyData(const ImageKeyData&) = delete;
+    ImageKeyData& operator=(const ImageKeyData&) = delete;
+
+    void MergeDirtyRect(const Maybe<gfx::IntRect>& aDirtyRect);
+
+    Maybe<gfx::IntRect> TakeDirtyRect() { return std::move(mDirtyRect); }
+
+    RefPtr<RenderRootStateManager> mManager;
+    Maybe<gfx::IntRect> mDirtyRect;
+    wr::ImageKey mImageKey;
+  };
+
+ private:
+  SharedSurfacesChild() = delete;
+  ~SharedSurfacesChild() = delete;
+
+  friend class SharedSurfacesAnimation;
+
+  class SharedUserData final : public Runnable {
+   public:
+    SharedUserData();
+    virtual ~SharedUserData();
+
+    SharedUserData(const SharedUserData& aOther) = delete;
+    SharedUserData& operator=(const SharedUserData& aOther) = delete;
+
+    SharedUserData(SharedUserData&& aOther) = delete;
+    SharedUserData& operator=(SharedUserData&& aOther) = delete;
+
+    static void Destroy(void* aClosure);
+
+    NS_IMETHOD Run() override;
+
+    const wr::ExternalImageId& Id() const { return mId; }
+
+    void ClearShared() {
+      mKeys.Clear();
+      mShared = false;
+    }
+
+    bool IsShared() const { return mShared; }
+
+    void MarkShared(const wr::ExternalImageId& aId) {
+      MOZ_ASSERT(!mShared);
+      mId = aId;
+      mShared = true;
+    }
+
+    wr::ImageKey UpdateKey(RenderRootStateManager* aManager,
+                           wr::IpcResourceUpdateQueue& aResources,
+                           const Maybe<gfx::IntRect>& aDirtyRect);
+
+   protected:
+    AutoTArray<ImageKeyData, 1> mKeys;
+    wr::ExternalImageId mId;
+    bool mShared : 1;
+  };
+
+  static nsresult ShareInternal(gfx::SourceSurfaceSharedData* aSurface,
+                                SharedUserData** aUserData);
+
+  static void Unshare(const wr::ExternalImageId& aId, bool aReleaseId,
+                      nsTArray<ImageKeyData>& aKeys);
+
+  static void DestroySharedUserData(void* aClosure);
+
+  static gfx::UserDataKey sSharedKey;
+};
+
+class AnimationImageKeyData final : public SharedSurfacesChild::ImageKeyData {
+ public:
+  AnimationImageKeyData(RenderRootStateManager* aManager,
+                        const wr::ImageKey& aImageKey);
+
+  virtual ~AnimationImageKeyData();
+
+  AnimationImageKeyData(AnimationImageKeyData&& aOther);
+  AnimationImageKeyData& operator=(AnimationImageKeyData&& aOther);
+
+  AutoTArray<RefPtr<gfx::SourceSurfaceSharedData>, 2> mPendingRelease;
+};
+
+/**
+ * This helper class owns a single ImageKey which will map to different external
+ * image IDs representing different frames in an animation.
+ */
+class SharedSurfacesAnimation final {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SharedSurfacesAnimation)
+
+  SharedSurfacesAnimation() = default;
+
+  void Destroy();
+
+  /**
+   * Set the animation to display the given frame.
+   * @param aSurface    The current frame.
+   * @param aDirtyRect  Dirty rect representing the change between the new frame
+   *                    and the previous frame. We will request only the delta
+   *                    be reuploaded by WebRender.
+   */
+  nsresult SetCurrentFrame(gfx::SourceSurfaceSharedData* aSurface,
+                           const gfx::IntRect& aDirtyRect);
+
+  /**
+   * Generate an ImageKey for the given frame.
+   * @param aSurface  The current frame. This should match what was cached via
+   *                  SetCurrentFrame, but if it does not, it will need to
+   *                  regenerate the cached ImageKey.
+   */
+  nsresult UpdateKey(gfx::SourceSurfaceSharedData* aSurface,
+                     RenderRootStateManager* aManager,
+                     wr::IpcResourceUpdateQueue& aResources,
+                     wr::ImageKey& aKey);
+
+  /**
+   * Release our reference to all frames up to and including the frame which
+   * has an external image ID which matches aId.
+   */
+  void ReleasePreviousFrame(RenderRootStateManager* aManager,
+                            const wr::ExternalImageId& aId);
+
+  /**
+   * Destroy any state information bound for the given layer manager. Any
+   * image keys are already invalid.
+   */
+  void Invalidate(RenderRootStateManager* aManager);
+
+ private:
+  ~SharedSurfacesAnimation();
+
+  void HoldSurfaceForRecycling(AnimationImageKeyData& aEntry,
+                               gfx::SourceSurfaceSharedData* aSurface);
+
+  AutoTArray<AnimationImageKeyData, 1> mKeys;
+  wr::ExternalImageId mId;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/SharedSurfacesMemoryReport.h b/gfx/layers/ipc/SharedSurfacesMemoryReport.h
new file mode 100644
index 0000000000..81baf1349f
--- /dev/null
+++ b/gfx/layers/ipc/SharedSurfacesMemoryReport.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_SHAREDSURFACESMEMORYREPORT_H
+#define MOZILLA_GFX_SHAREDSURFACESMEMORYREPORT_H
+
+#include <cstdint>  // for uint32_t
+#include <unordered_map>
+#include "base/process.h"
+#include "ipc/IPCMessageUtils.h"
+#include "ipc/IPCMessageUtilsSpecializations.h"
+#include "mozilla/gfx/Point.h"  // for IntSize
+
+namespace mozilla {
+namespace layers {
+
+class SharedSurfacesMemoryReport final {
+ public:
+  class SurfaceEntry final {
+   public:
+    base::ProcessId mCreatorPid;
+    gfx::IntSize mSize;
+    int32_t mStride;
+    uint32_t mConsumers;
+    bool mCreatorRef;
+  };
+
+  std::unordered_map<uint64_t, SurfaceEntry> mSurfaces;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::layers::SharedSurfacesMemoryReport> {
+  typedef mozilla::layers::SharedSurfacesMemoryReport paramType;
+
+  static void Write(MessageWriter* aWriter, const paramType& aParam) {
+    WriteParam(aWriter, aParam.mSurfaces);
+  }
+
+  static bool Read(MessageReader* aReader, paramType* aResult) {
+    return ReadParam(aReader, &aResult->mSurfaces);
+  }
+};
+
+template <>
+struct ParamTraits<mozilla::layers::SharedSurfacesMemoryReport::SurfaceEntry>
+    : public PlainOldDataSerializer<
+          mozilla::layers::SharedSurfacesMemoryReport::SurfaceEntry> {};
+
+}  // namespace IPC
+
+#endif
diff --git a/gfx/layers/ipc/SharedSurfacesParent.cpp b/gfx/layers/ipc/SharedSurfacesParent.cpp
new file mode 100644
index 0000000000..932a7558ad
--- /dev/null
+++ b/gfx/layers/ipc/SharedSurfacesParent.cpp
@@ -0,0 +1,405 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SharedSurfacesParent.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/StaticPrefs_image.h"
+#include "mozilla/gfx/Logging.h"
+#include "mozilla/gfx/gfxVars.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/layers/SharedSurfacesMemoryReport.h"
+#include "mozilla/layers/SourceSurfaceSharedData.h"
+#include "mozilla/layers/CompositorManagerParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/webrender/RenderSharedSurfaceTextureHost.h"
+#include "mozilla/webrender/RenderThread.h"
+#include "nsThreadUtils.h"  // for GetCurrentSerialEventTarget
+
+namespace mozilla {
+namespace layers {
+
+using namespace mozilla::gfx;
+
+StaticMutex SharedSurfacesParent::sMutex;
+StaticAutoPtr<SharedSurfacesParent> SharedSurfacesParent::sInstance;
+
+void SharedSurfacesParent::MappingTracker::NotifyExpiredLocked(
+    SourceSurfaceSharedDataWrapper* aSurface,
+    const StaticMutexAutoLock& aAutoLock) {
+  RemoveObjectLocked(aSurface, aAutoLock);
+  mExpired.AppendElement(aSurface);
+}
+
+void SharedSurfacesParent::MappingTracker::TakeExpired(
+    nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>>& aExpired,
+    const StaticMutexAutoLock& aAutoLock) {
+  aExpired = std::move(mExpired);
+}
+
+void SharedSurfacesParent::MappingTracker::NotifyHandlerEnd() {
+  nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>> expired;
+  {
+    StaticMutexAutoLock lock(sMutex);
+    TakeExpired(expired, lock);
+  }
+
+  SharedSurfacesParent::ExpireMap(expired);
+}
+
+SharedSurfacesParent::SharedSurfacesParent()
+    : mTracker(
+          StaticPrefs::image_mem_shared_unmap_min_expiration_ms_AtStartup(),
+          mozilla::GetCurrentSerialEventTarget()) {}
+
+/* static */
+void SharedSurfacesParent::Initialize() {
+  MOZ_ASSERT(NS_IsMainThread());
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    sInstance = new SharedSurfacesParent();
+  }
+}
+
+/* static */
+void SharedSurfacesParent::ShutdownRenderThread() {
+  // The main thread should blocked on waiting for the render thread to
+  // complete so this should be safe to release off the main thread.
+  MOZ_ASSERT(wr::RenderThread::IsInRenderThread());
+  StaticMutexAutoLock lock(sMutex);
+  MOZ_ASSERT(sInstance);
+
+  for (const auto& key : sInstance->mSurfaces.Keys()) {
+    // There may be lingering consumers of the surfaces that didn't get shutdown
+    // yet but since we are here, we know the render thread is finished and we
+    // can unregister everything.
+    wr::RenderThread::Get()->UnregisterExternalImageDuringShutdown(
+        wr::ToExternalImageId(key));
+  }
+}
+
+/* static */
+void SharedSurfacesParent::Shutdown() {
+  // The compositor thread and render threads are shutdown, so this is the last
+  // thread that could use it. The expiration tracker needs to be freed on the
+  // main thread.
+  MOZ_ASSERT(NS_IsMainThread());
+  StaticMutexAutoLock lock(sMutex);
+  sInstance = nullptr;
+}
+
+/* static */
+already_AddRefed<DataSourceSurface> SharedSurfacesParent::Get(
+    const wr::ExternalImageId& aId) {
+  RefPtr<SourceSurfaceSharedDataWrapper> surface;
+
+  {
+    StaticMutexAutoLock lock(sMutex);
+    if (!sInstance) {
+      gfxCriticalNote << "SSP:Get " << wr::AsUint64(aId) << " shtd";
+      return nullptr;
+    }
+
+    if (sInstance->mSurfaces.Get(wr::AsUint64(aId), getter_AddRefs(surface))) {
+      return surface.forget();
+    }
+  }
+
+  // We cannot block the compositor thread since that's the thread the necessary
+  // IPDL events would come in on.
+  if (NS_WARN_IF(CompositorThreadHolder::IsInCompositorThread())) {
+    return nullptr;
+  }
+
+  // Block until we see the relevant resource come in or the actor is destroyed.
+  CompositorManagerParent::WaitForSharedSurface(aId);
+
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    gfxCriticalNote << "SSP:Get " << wr::AsUint64(aId) << " shtd";
+    return nullptr;
+  }
+
+  sInstance->mSurfaces.Get(wr::AsUint64(aId), getter_AddRefs(surface));
+  return surface.forget();
+}
+
+/* static */
+already_AddRefed<DataSourceSurface> SharedSurfacesParent::Acquire(
+    const wr::ExternalImageId& aId) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    gfxCriticalNote << "SSP:Acq " << wr::AsUint64(aId) << " shtd";
+    return nullptr;
+  }
+
+  RefPtr<SourceSurfaceSharedDataWrapper> surface;
+  sInstance->mSurfaces.Get(wr::AsUint64(aId), getter_AddRefs(surface));
+
+  if (surface) {
+    DebugOnly<bool> rv = surface->AddConsumer();
+    MOZ_ASSERT(!rv);
+  }
+  return surface.forget();
+}
+
+/* static */
+bool SharedSurfacesParent::Release(const wr::ExternalImageId& aId,
+                                   bool aForCreator) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return false;
+  }
+
+  uint64_t id = wr::AsUint64(aId);
+  RefPtr<SourceSurfaceSharedDataWrapper> surface;
+  sInstance->mSurfaces.Get(wr::AsUint64(aId), getter_AddRefs(surface));
+  if (!surface) {
+    return false;
+  }
+
+  if (surface->RemoveConsumer(aForCreator)) {
+    RemoveTrackingLocked(surface, lock);
+    wr::RenderThread::Get()->UnregisterExternalImage(wr::ToExternalImageId(id));
+    sInstance->mSurfaces.Remove(id);
+  }
+
+  return true;
+}
+
+/* static */
+void SharedSurfacesParent::AddSameProcess(const wr::ExternalImageId& aId,
+                                          SourceSurfaceSharedData* aSurface) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+  MOZ_ASSERT(NS_IsMainThread());
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    gfxCriticalNote << "SSP:Ads " << wr::AsUint64(aId) << " shtd";
+    return;
+  }
+
+  // If the child bridge detects it is in the combined UI/GPU process, then it
+  // will insert a wrapper surface holding the shared memory buffer directly.
+  // This is good because we avoid mapping the same shared memory twice, but
+  // still allow the original surface to be freed and remove the wrapper from
+  // the table when it is no longer needed.
+  RefPtr<SourceSurfaceSharedDataWrapper> surface =
+      new SourceSurfaceSharedDataWrapper();
+  surface->Init(aSurface);
+
+  uint64_t id = wr::AsUint64(aId);
+  MOZ_ASSERT(!sInstance->mSurfaces.Contains(id));
+
+  auto texture = MakeRefPtr<wr::RenderSharedSurfaceTextureHost>(surface);
+  wr::RenderThread::Get()->RegisterExternalImage(aId, texture.forget());
+
+  surface->AddConsumer();
+  sInstance->mSurfaces.InsertOrUpdate(id, std::move(surface));
+}
+
+/* static */
+void SharedSurfacesParent::RemoveAll(uint32_t aNamespace) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return;
+  }
+
+  auto* renderThread = wr::RenderThread::Get();
+
+  // Note that the destruction of a parent may not be cheap if it still has a
+  // lot of surfaces still bound that require unmapping.
+  for (auto i = sInstance->mSurfaces.Iter(); !i.Done(); i.Next()) {
+    if (static_cast<uint32_t>(i.Key() >> 32) != aNamespace) {
+      continue;
+    }
+
+    SourceSurfaceSharedDataWrapper* surface = i.Data();
+    if (surface->HasCreatorRef() &&
+        surface->RemoveConsumer(/* aForCreator */ true)) {
+      RemoveTrackingLocked(surface, lock);
+      if (renderThread) {
+        renderThread->UnregisterExternalImage(wr::ToExternalImageId(i.Key()));
+      }
+      i.Remove();
+    }
+  }
+}
+
+/* static */
+void SharedSurfacesParent::Add(const wr::ExternalImageId& aId,
+                               SurfaceDescriptorShared&& aDesc,
+                               base::ProcessId aPid) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  MOZ_ASSERT(aPid != base::GetCurrentProcId());
+
+  RefPtr<SourceSurfaceSharedDataWrapper> surface =
+      new SourceSurfaceSharedDataWrapper();
+
+  // We preferentially map in new surfaces when they are initially received
+  // because we are likely to reference them in a display list soon. The unmap
+  // will ensure we add the surface to the expiration tracker. We do it outside
+  // the mutex to ensure we always lock the surface mutex first, and our mutex
+  // second, to avoid deadlock.
+  //
+  // Note that the surface wrapper maps in the given handle as read only.
+  surface->Init(aDesc.size(), aDesc.stride(), aDesc.format(),
+                std::move(aDesc.handle()), aPid);
+
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    gfxCriticalNote << "SSP:Add " << wr::AsUint64(aId) << " shtd";
+    return;
+  }
+
+  uint64_t id = wr::AsUint64(aId);
+  MOZ_ASSERT(!sInstance->mSurfaces.Contains(id));
+
+  auto texture = MakeRefPtr<wr::RenderSharedSurfaceTextureHost>(surface);
+  wr::RenderThread::Get()->RegisterExternalImage(aId, texture.forget());
+
+  surface->AddConsumer();
+  sInstance->mSurfaces.InsertOrUpdate(id, std::move(surface));
+}
+
+/* static */
+void SharedSurfacesParent::Remove(const wr::ExternalImageId& aId) {
+  DebugOnly<bool> rv = Release(aId, /* aForCreator */ true);
+  MOZ_ASSERT(rv);
+}
+
+/* static */
+void SharedSurfacesParent::AddTrackingLocked(
+    SourceSurfaceSharedDataWrapper* aSurface,
+    const StaticMutexAutoLock& aAutoLock) {
+  MOZ_ASSERT(!aSurface->GetExpirationState()->IsTracked());
+  sInstance->mTracker.AddObjectLocked(aSurface, aAutoLock);
+}
+
+/* static */
+void SharedSurfacesParent::AddTracking(
+    SourceSurfaceSharedDataWrapper* aSurface) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return;
+  }
+
+  AddTrackingLocked(aSurface, lock);
+}
+
+/* static */
+void SharedSurfacesParent::RemoveTrackingLocked(
+    SourceSurfaceSharedDataWrapper* aSurface,
+    const StaticMutexAutoLock& aAutoLock) {
+  if (!aSurface->GetExpirationState()->IsTracked()) {
+    return;
+  }
+
+  sInstance->mTracker.RemoveObjectLocked(aSurface, aAutoLock);
+}
+
+/* static */
+void SharedSurfacesParent::RemoveTracking(
+    SourceSurfaceSharedDataWrapper* aSurface) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return;
+  }
+
+  RemoveTrackingLocked(aSurface, lock);
+}
+
+/* static */
+bool SharedSurfacesParent::AgeOneGenerationLocked(
+    nsTArray<RefPtr<SourceSurfaceSharedDataWrapper>>& aExpired,
+    const StaticMutexAutoLock& aAutoLock) {
+  if (sInstance->mTracker.IsEmptyLocked(aAutoLock)) {
+    return false;
+  }
+
+  sInstance->mTracker.AgeOneGenerationLocked(aAutoLock);
+  sInstance->mTracker.TakeExpired(aExpired, aAutoLock);
+  return true;
+}
+
+/* static */
+bool SharedSurfacesParent::AgeOneGeneration(
+    nsTArray<RefPtr<SourceSurfaceSharedDataWrapper>>& aExpired) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return false;
+  }
+
+  return AgeOneGenerationLocked(aExpired, lock);
+}
+
+/* static */
+bool SharedSurfacesParent::AgeAndExpireOneGeneration() {
+  nsTArray<RefPtr<SourceSurfaceSharedDataWrapper>> expired;
+  bool aged = AgeOneGeneration(expired);
+  ExpireMap(expired);
+  return aged;
+}
+
+/* static */
+void SharedSurfacesParent::ExpireMap(
+    nsTArray<RefPtr<SourceSurfaceSharedDataWrapper>>& aExpired) {
+  for (auto& surface : aExpired) {
+    surface->ExpireMap();
+  }
+}
+
+/* static */
+void SharedSurfacesParent::AccumulateMemoryReport(
+    uint32_t aNamespace, SharedSurfacesMemoryReport& aReport) {
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return;
+  }
+
+  for (const auto& entry : sInstance->mSurfaces) {
+    if (static_cast<uint32_t>(entry.GetKey() >> 32) != aNamespace) {
+      continue;
+    }
+
+    SourceSurfaceSharedDataWrapper* surface = entry.GetData();
+    aReport.mSurfaces.insert(std::make_pair(
+        entry.GetKey(),
+        SharedSurfacesMemoryReport::SurfaceEntry{
+            surface->GetCreatorPid(), surface->GetSize(), surface->Stride(),
+            surface->GetConsumers(), surface->HasCreatorRef()}));
+  }
+}
+
+/* static */
+bool SharedSurfacesParent::AccumulateMemoryReport(
+    SharedSurfacesMemoryReport& aReport) {
+  if (XRE_IsParentProcess()) {
+    GPUProcessManager* gpm = GPUProcessManager::Get();
+    if (!gpm || gpm->GPUProcessPid() != base::kInvalidProcessId) {
+      return false;
+    }
+  } else if (!XRE_IsGPUProcess()) {
+    return false;
+  }
+
+  StaticMutexAutoLock lock(sMutex);
+  if (!sInstance) {
+    return true;
+  }
+
+  for (const auto& entry : sInstance->mSurfaces) {
+    SourceSurfaceSharedDataWrapper* surface = entry.GetData();
+    aReport.mSurfaces.insert(std::make_pair(
+        entry.GetKey(),
+        SharedSurfacesMemoryReport::SurfaceEntry{
+            surface->GetCreatorPid(), surface->GetSize(), surface->Stride(),
+            surface->GetConsumers(), surface->HasCreatorRef()}));
+  }
+
+  return true;
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/SharedSurfacesParent.h b/gfx/layers/ipc/SharedSurfacesParent.h
new file mode 100644
index 0000000000..b62c4a5d81
--- /dev/null
+++ b/gfx/layers/ipc/SharedSurfacesParent.h
@@ -0,0 +1,162 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_SHAREDSURFACESPARENT_H
+#define MOZILLA_GFX_SHAREDSURFACESPARENT_H
+
+#include <stdint.h>                         // for uint32_t
+#include "mozilla/Attributes.h"             // for override
+#include "mozilla/StaticMutex.h"            // for StaticMutex
+#include "mozilla/StaticPtr.h"              // for StaticAutoPtr
+#include "mozilla/RefPtr.h"                 // for already_AddRefed
+#include "mozilla/ipc/SharedMemory.h"       // for SharedMemory, etc
+#include "mozilla/gfx/2D.h"                 // for SurfaceFormat
+#include "mozilla/gfx/Point.h"              // for IntSize
+#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptorShared
+#include "mozilla/layers/SourceSurfaceSharedData.h"
+#include "mozilla/webrender/WebRenderTypes.h"  // for wr::ExternalImageId
+#include "nsExpirationTracker.h"
+#include "nsRefPtrHashtable.h"
+
+namespace mozilla {
+namespace gfx {
+class DataSourceSurface;
+}  // namespace gfx
+
+namespace layers {
+
+class CompositorManagerParent;
+class SharedSurfacesMemoryReport;
+
+class SharedSurfacesParent final {
+ public:
+  static void Initialize();
+  static void ShutdownRenderThread();
+  static void Shutdown();
+
+  // Get without increasing the consumer count.
+  static already_AddRefed<gfx::DataSourceSurface> Get(
+      const wr::ExternalImageId& aId);
+
+  // Get but also increase the consumer count. Must call Release after finished.
+  static already_AddRefed<gfx::DataSourceSurface> Acquire(
+      const wr::ExternalImageId& aId);
+
+  static bool Release(const wr::ExternalImageId& aId, bool aForCreator = false);
+
+  static void Add(const wr::ExternalImageId& aId,
+                  SurfaceDescriptorShared&& aDesc, base::ProcessId aPid);
+
+  static void Remove(const wr::ExternalImageId& aId);
+
+  static void RemoveAll(uint32_t aNamespace);
+
+  static void AccumulateMemoryReport(uint32_t aNamespace,
+                                     SharedSurfacesMemoryReport& aReport);
+
+  static bool AccumulateMemoryReport(SharedSurfacesMemoryReport& aReport);
+
+  static void AddTracking(gfx::SourceSurfaceSharedDataWrapper* aSurface);
+
+  static void RemoveTracking(gfx::SourceSurfaceSharedDataWrapper* aSurface);
+
+  static bool AgeOneGeneration(
+      nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>>& aExpired);
+
+  static bool AgeAndExpireOneGeneration();
+
+ private:
+  friend class CompositorManagerParent;
+  friend class gfx::SourceSurfaceSharedDataWrapper;
+
+  SharedSurfacesParent();
+
+  static void AddSameProcess(const wr::ExternalImageId& aId,
+                             gfx::SourceSurfaceSharedData* aSurface);
+
+  static void AddTrackingLocked(gfx::SourceSurfaceSharedDataWrapper* aSurface,
+                                const StaticMutexAutoLock& aAutoLock);
+
+  static void RemoveTrackingLocked(
+      gfx::SourceSurfaceSharedDataWrapper* aSurface,
+      const StaticMutexAutoLock& aAutoLock);
+
+  static bool AgeOneGenerationLocked(
+      nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>>& aExpired,
+      const StaticMutexAutoLock& aAutoLock);
+
+  static void ExpireMap(
+      nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>>& aExpired);
+
+  static StaticMutex sMutex MOZ_UNANNOTATED;
+
+  static StaticAutoPtr<SharedSurfacesParent> sInstance;
+
+  nsRefPtrHashtable<nsUint64HashKey, gfx::SourceSurfaceSharedDataWrapper>
+      mSurfaces;
+
+  class MappingTracker final
+      : public ExpirationTrackerImpl<gfx::SourceSurfaceSharedDataWrapper, 4,
+                                     StaticMutex, StaticMutexAutoLock> {
+   public:
+    explicit MappingTracker(uint32_t aExpirationTimeoutMS,
+                            nsIEventTarget* aEventTarget)
+        : ExpirationTrackerImpl<gfx::SourceSurfaceSharedDataWrapper, 4,
+                                StaticMutex, StaticMutexAutoLock>(
+              aExpirationTimeoutMS, "SharedMappingTracker", aEventTarget) {}
+
+    void TakeExpired(
+        nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>>& aExpired,
+        const StaticMutexAutoLock& aAutoLock);
+
+   protected:
+    void NotifyExpiredLocked(gfx::SourceSurfaceSharedDataWrapper* aSurface,
+                             const StaticMutexAutoLock& aAutoLock) override;
+
+    void NotifyHandlerEndLocked(const StaticMutexAutoLock& aAutoLock) override {
+    }
+
+    void NotifyHandlerEnd() override;
+
+    StaticMutex& GetMutex() override { return sMutex; }
+
+    nsTArray<RefPtr<gfx::SourceSurfaceSharedDataWrapper>> mExpired;
+  };
+
+  MappingTracker mTracker;
+};
+
+/**
+ * Helper class that is used to keep SourceSurfaceSharedDataWrapper objects
+ * around as long as one of the dependent IPDL actors is still alive and may
+ * reference them for a given PCompositorManager namespace.
+ */
+class SharedSurfacesHolder final {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(SharedSurfacesHolder)
+
+ public:
+  explicit SharedSurfacesHolder(uint32_t aNamespace) : mNamespace(aNamespace) {}
+
+  already_AddRefed<gfx::DataSourceSurface> Get(const wr::ExternalImageId& aId) {
+    uint32_t extNamespace = static_cast<uint32_t>(wr::AsUint64(aId) >> 32);
+    if (NS_WARN_IF(extNamespace != mNamespace)) {
+      MOZ_ASSERT_UNREACHABLE("Wrong namespace?");
+      return nullptr;
+    }
+
+    return SharedSurfacesParent::Get(aId);
+  }
+
+ private:
+  ~SharedSurfacesHolder() { SharedSurfacesParent::RemoveAll(mNamespace); }
+
+  uint32_t mNamespace;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/SurfaceDescriptor.h b/gfx/layers/ipc/SurfaceDescriptor.h
new file mode 100644
index 0000000000..6d4c2d3271
--- /dev/null
+++ b/gfx/layers/ipc/SurfaceDescriptor.h
@@ -0,0 +1,14 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef IPC_SurfaceDescriptor_h
+#define IPC_SurfaceDescriptor_h
+
+#if defined(XP_MACOSX)
+#  define MOZ_HAVE_PLATFORM_SPECIFIC_LAYER_BUFFERS
+#endif
+
+#endif  // IPC_SurfaceDescriptor_h
diff --git a/gfx/layers/ipc/SynchronousTask.h b/gfx/layers/ipc/SynchronousTask.h
new file mode 100644
index 0000000000..a7091eb8cb
--- /dev/null
+++ b/gfx/layers/ipc/SynchronousTask.h
@@ -0,0 +1,72 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_SYNCHRONOUSTASK_H
+#define MOZILLA_GFX_SYNCHRONOUSTASK_H
+
+#include "mozilla/ReentrantMonitor.h"  // for ReentrantMonitor, etc
+
+namespace mozilla {
+namespace layers {
+
+// Helper that creates a monitor and a "done" flag, then enters the monitor.
+class MOZ_STACK_CLASS SynchronousTask {
+  friend class AutoCompleteTask;
+
+ public:
+  explicit SynchronousTask(const char* name) : mMonitor(name), mDone(false) {}
+
+  nsresult Wait(PRIntervalTime aInterval = PR_INTERVAL_NO_TIMEOUT) {
+    ReentrantMonitorAutoEnter lock(mMonitor);
+
+    // For indefinite timeouts, wait in a while loop to handle spurious
+    // wakeups.
+    while (aInterval == PR_INTERVAL_NO_TIMEOUT && !mDone) {
+      mMonitor.Wait();
+    }
+
+    // For finite timeouts, we only check once for completion, and otherwise
+    // rely on the ReentrantMonitor to manage the interval. If the monitor
+    // returns too early, we'll never know, but we can check if the mDone
+    // flag was set to true, indicating that the task finished successfully.
+    if (!mDone) {
+      // We ignore the return value from ReentrantMonitor::Wait, because it's
+      // always NS_OK, even in the case of timeout.
+      mMonitor.Wait(aInterval);
+
+      if (!mDone) {
+        return NS_ERROR_ABORT;
+      }
+    }
+
+    return NS_OK;
+  }
+
+ private:
+  void Complete() {
+    ReentrantMonitorAutoEnter lock(mMonitor);
+    mDone = true;
+    mMonitor.NotifyAll();
+  }
+
+ private:
+  ReentrantMonitor mMonitor MOZ_UNANNOTATED;
+  bool mDone;
+};
+
+class MOZ_STACK_CLASS AutoCompleteTask final {
+ public:
+  explicit AutoCompleteTask(SynchronousTask* aTask) : mTask(aTask) {}
+  ~AutoCompleteTask() { mTask->Complete(); }
+
+ private:
+  SynchronousTask* mTask;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/TextureForwarder.h b/gfx/layers/ipc/TextureForwarder.h
new file mode 100644
index 0000000000..af84390143
--- /dev/null
+++ b/gfx/layers/ipc/TextureForwarder.h
@@ -0,0 +1,92 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_LAYERS_TEXTUREFORWARDER
+#define MOZILLA_LAYERS_TEXTUREFORWARDER
+
+#include <stdint.h>  // for int32_t, uint64_t
+#include "gfxTypes.h"
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/layers/LayersMessages.h"  // for Edit, etc
+#include "mozilla/layers/LayersTypes.h"     // for LayersBackend
+#include "mozilla/layers/TextureClient.h"   // for TextureClient
+#include "mozilla/layers/KnowsCompositor.h"
+#include "nsISerialEventTarget.h"
+
+namespace mozilla {
+namespace layers {
+class CanvasChild;
+
+/**
+ * An abstract interface for classes that implement the autogenerated
+ * IPDL actor class. Lets us check if they are still valid for IPC.
+ */
+class LayersIPCActor {
+ public:
+  virtual bool IPCOpen() const { return true; }
+};
+
+/**
+ * An abstract interface for LayersIPCActors that implement a top-level
+ * IPDL protocol so also have their own channel.
+ * Has their own MessageLoop for message dispatch, and can allocate
+ * shmem.
+ */
+class LayersIPCChannel : public LayersIPCActor,
+                         public mozilla::ipc::IShmemAllocator {
+ public:
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+  virtual bool IsSameProcess() const = 0;
+
+  virtual bool UsesImageBridge() const { return false; }
+
+  virtual base::ProcessId GetParentPid() const = 0;
+
+  virtual nsISerialEventTarget* GetThread() const = 0;
+
+  virtual FixedSizeSmallShmemSectionAllocator* GetTileLockAllocator() {
+    return nullptr;
+  }
+
+  virtual void CancelWaitForNotifyNotUsed(uint64_t aTextureId) = 0;
+
+  virtual wr::MaybeExternalImageId GetNextExternalImageId() {
+    return Nothing();
+  }
+
+ protected:
+  virtual ~LayersIPCChannel() = default;
+};
+
+/**
+ * An abstract interface for classes that can allocate PTexture objects
+ * across IPDL. Currently a sub-class of LayersIPCChannel for simplicity
+ * since all our implementations use both, but could be independant if needed.
+ */
+class TextureForwarder : public LayersIPCChannel {
+ public:
+  /**
+   * Create a TextureChild/Parent pair as as well as the TextureHost on the
+   * parent side.
+   */
+  virtual PTextureChild* CreateTexture(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+      LayersBackend aLayersBackend, TextureFlags aFlags,
+      const dom::ContentParentId& aContentId, uint64_t aSerial,
+      wr::MaybeExternalImageId& aExternalImageId) = 0;
+
+  /**
+   * Returns the CanvasChild for this TextureForwarder.
+   */
+  virtual already_AddRefed<CanvasChild> GetCanvasChild() { return nullptr; };
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/UiCompositorControllerChild.cpp b/gfx/layers/ipc/UiCompositorControllerChild.cpp
new file mode 100644
index 0000000000..c1bf49bc27
--- /dev/null
+++ b/gfx/layers/ipc/UiCompositorControllerChild.cpp
@@ -0,0 +1,350 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/layers/UiCompositorControllerChild.h"
+
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/SynchronousTask.h"
+#include "mozilla/layers/UiCompositorControllerMessageTypes.h"
+#include "mozilla/layers/UiCompositorControllerParent.h"
+#include "mozilla/gfx/GPUProcessManager.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/StaticPtr.h"
+#include "nsBaseWidget.h"
+#include "nsProxyRelease.h"
+#include "nsThreadUtils.h"
+
+#if defined(MOZ_WIDGET_ANDROID)
+#  include "mozilla/widget/AndroidUiThread.h"
+
+static RefPtr<nsThread> GetUiThread() { return mozilla::GetAndroidUiThread(); }
+#else
+static RefPtr<nsThread> GetUiThread() {
+  MOZ_CRASH("Platform does not support UiCompositorController");
+  return nullptr;
+}
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+namespace mozilla {
+namespace layers {
+
+// public:
+/* static */
+RefPtr<UiCompositorControllerChild>
+UiCompositorControllerChild::CreateForSameProcess(
+    const LayersId& aRootLayerTreeId, nsBaseWidget* aWidget) {
+  RefPtr<UiCompositorControllerChild> child =
+      new UiCompositorControllerChild(0, aWidget);
+  child->mParent = new UiCompositorControllerParent(aRootLayerTreeId);
+  GetUiThread()->Dispatch(
+      NewRunnableMethod(
+          "layers::UiCompositorControllerChild::OpenForSameProcess", child,
+          &UiCompositorControllerChild::OpenForSameProcess),
+      nsIThread::DISPATCH_NORMAL);
+  return child;
+}
+
+/* static */
+RefPtr<UiCompositorControllerChild>
+UiCompositorControllerChild::CreateForGPUProcess(
+    const uint64_t& aProcessToken,
+    Endpoint<PUiCompositorControllerChild>&& aEndpoint, nsBaseWidget* aWidget) {
+  RefPtr<UiCompositorControllerChild> child =
+      new UiCompositorControllerChild(aProcessToken, aWidget);
+
+  RefPtr<nsIRunnable> task =
+      NewRunnableMethod<Endpoint<PUiCompositorControllerChild>&&>(
+          "layers::UiCompositorControllerChild::OpenForGPUProcess", child,
+          &UiCompositorControllerChild::OpenForGPUProcess,
+          std::move(aEndpoint));
+
+  GetUiThread()->Dispatch(task.forget(), nsIThread::DISPATCH_NORMAL);
+  return child;
+}
+
+bool UiCompositorControllerChild::Pause() {
+  if (!mIsOpen) {
+    return false;
+  }
+  return SendPause();
+}
+
+bool UiCompositorControllerChild::Resume() {
+  if (!mIsOpen) {
+    return false;
+  }
+  bool resumed = false;
+  return SendResume(&resumed) && resumed;
+}
+
+bool UiCompositorControllerChild::ResumeAndResize(const int32_t& aX,
+                                                  const int32_t& aY,
+                                                  const int32_t& aWidth,
+                                                  const int32_t& aHeight) {
+  if (!mIsOpen) {
+    mResize = Some(gfx::IntRect(aX, aY, aWidth, aHeight));
+    // Since we are caching these values, pretend the call succeeded.
+    return true;
+  }
+  bool resumed = false;
+  return SendResumeAndResize(aX, aY, aWidth, aHeight, &resumed) && resumed;
+}
+
+bool UiCompositorControllerChild::InvalidateAndRender() {
+  if (!mIsOpen) {
+    return false;
+  }
+  return SendInvalidateAndRender();
+}
+
+bool UiCompositorControllerChild::SetMaxToolbarHeight(const int32_t& aHeight) {
+  if (!mIsOpen) {
+    mMaxToolbarHeight = Some(aHeight);
+    // Since we are caching this value, pretend the call succeeded.
+    return true;
+  }
+  return SendMaxToolbarHeight(aHeight);
+}
+
+bool UiCompositorControllerChild::SetFixedBottomOffset(int32_t aOffset) {
+  return SendFixedBottomOffset(aOffset);
+}
+
+bool UiCompositorControllerChild::ToolbarAnimatorMessageFromUI(
+    const int32_t& aMessage) {
+  if (!mIsOpen) {
+    return false;
+  }
+
+  if (aMessage == IS_COMPOSITOR_CONTROLLER_OPEN) {
+    RecvToolbarAnimatorMessageFromCompositor(COMPOSITOR_CONTROLLER_OPEN);
+  }
+
+  return true;
+}
+
+bool UiCompositorControllerChild::SetDefaultClearColor(const uint32_t& aColor) {
+  if (!mIsOpen) {
+    mDefaultClearColor = Some(aColor);
+    // Since we are caching this value, pretend the call succeeded.
+    return true;
+  }
+
+  return SendDefaultClearColor(aColor);
+}
+
+bool UiCompositorControllerChild::RequestScreenPixels() {
+  if (!mIsOpen) {
+    return false;
+  }
+
+  return SendRequestScreenPixels();
+}
+
+bool UiCompositorControllerChild::EnableLayerUpdateNotifications(
+    const bool& aEnable) {
+  if (!mIsOpen) {
+    mLayerUpdateEnabled = Some(aEnable);
+    // Since we are caching this value, pretend the call succeeded.
+    return true;
+  }
+
+  return SendEnableLayerUpdateNotifications(aEnable);
+}
+
+void UiCompositorControllerChild::Destroy() {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  layers::SynchronousTask task("UiCompositorControllerChild::Destroy");
+  GetUiThread()->Dispatch(NS_NewRunnableFunction(
+      "layers::UiCompositorControllerChild::Destroy", [&]() {
+        MOZ_ASSERT(GetUiThread()->IsOnCurrentThread());
+        AutoCompleteTask complete(&task);
+
+        // Clear the process token so that we don't notify the GPUProcessManager
+        // about an abnormal shutdown, thereby tearing down the GPU process.
+        mProcessToken = 0;
+
+        if (mWidget) {
+          // Dispatch mWidget to main thread to prevent it from being destructed
+          // by the ui thread.
+          RefPtr<nsIWidget> widget = std::move(mWidget);
+          NS_ReleaseOnMainThread("UiCompositorControllerChild::mWidget",
+                                 widget.forget());
+        }
+
+        if (mIsOpen) {
+          // Close the underlying IPC channel.
+          PUiCompositorControllerChild::Close();
+          mIsOpen = false;
+        }
+      }));
+
+  task.Wait();
+}
+
+bool UiCompositorControllerChild::DeallocPixelBuffer(Shmem& aMem) {
+  return DeallocShmem(aMem);
+}
+
+// protected:
+void UiCompositorControllerChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mIsOpen = false;
+  mParent = nullptr;
+
+  if (mProcessToken) {
+    gfx::GPUProcessManager::Get()->NotifyRemoteActorDestroyed(mProcessToken);
+    mProcessToken = 0;
+  }
+}
+
+void UiCompositorControllerChild::ProcessingError(Result aCode,
+                                                  const char* aReason) {
+  if (aCode != MsgDropped) {
+    gfxDevCrash(gfx::LogReason::ProcessingError)
+        << "Processing error in UiCompositorControllerChild: " << int(aCode);
+  }
+}
+
+void UiCompositorControllerChild::HandleFatalError(const char* aMsg) {
+  dom::ContentChild::FatalErrorIfNotUsingGPUProcess(aMsg, OtherPid());
+}
+
+mozilla::ipc::IPCResult
+UiCompositorControllerChild::RecvToolbarAnimatorMessageFromCompositor(
+    const int32_t& aMessage) {
+#if defined(MOZ_WIDGET_ANDROID)
+  if (mWidget) {
+    mWidget->RecvToolbarAnimatorMessageFromCompositor(aMessage);
+  }
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerChild::RecvRootFrameMetrics(
+    const ScreenPoint& aScrollOffset, const CSSToScreenScale& aZoom) {
+#if defined(MOZ_WIDGET_ANDROID)
+  if (mWidget) {
+    mWidget->UpdateRootFrameMetrics(aScrollOffset, aZoom);
+  }
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerChild::RecvScreenPixels(
+    ipc::Shmem&& aMem, const ScreenIntSize& aSize, bool aNeedsYFlip) {
+#if defined(MOZ_WIDGET_ANDROID)
+  if (mWidget) {
+    mWidget->RecvScreenPixels(std::move(aMem), aSize, aNeedsYFlip);
+  }
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+// private:
+UiCompositorControllerChild::UiCompositorControllerChild(
+    const uint64_t& aProcessToken, nsBaseWidget* aWidget)
+    : mIsOpen(false), mProcessToken(aProcessToken), mWidget(aWidget) {}
+
+UiCompositorControllerChild::~UiCompositorControllerChild() = default;
+
+void UiCompositorControllerChild::OpenForSameProcess() {
+  MOZ_ASSERT(GetUiThread()->IsOnCurrentThread());
+
+  mIsOpen = Open(mParent, mozilla::layers::CompositorThread(),
+                 mozilla::ipc::ChildSide);
+
+  if (!mIsOpen) {
+    mParent = nullptr;
+    return;
+  }
+
+  mParent->InitializeForSameProcess();
+  SendCachedValues();
+  // Let Ui thread know the connection is open;
+  RecvToolbarAnimatorMessageFromCompositor(COMPOSITOR_CONTROLLER_OPEN);
+}
+
+void UiCompositorControllerChild::OpenForGPUProcess(
+    Endpoint<PUiCompositorControllerChild>&& aEndpoint) {
+  MOZ_ASSERT(GetUiThread()->IsOnCurrentThread());
+
+  mIsOpen = aEndpoint.Bind(this);
+
+  if (!mIsOpen) {
+    // The GPU Process Manager might be gone if we receive ActorDestroy very
+    // late in shutdown.
+    if (gfx::GPUProcessManager* gpm = gfx::GPUProcessManager::Get()) {
+      gpm->NotifyRemoteActorDestroyed(mProcessToken);
+    }
+    return;
+  }
+
+  SendCachedValues();
+  // Let Ui thread know the connection is open;
+  RecvToolbarAnimatorMessageFromCompositor(COMPOSITOR_CONTROLLER_OPEN);
+}
+
+void UiCompositorControllerChild::SendCachedValues() {
+  MOZ_ASSERT(mIsOpen);
+  if (mResize) {
+    bool resumed;
+    SendResumeAndResize(mResize.ref().x, mResize.ref().y, mResize.ref().width,
+                        mResize.ref().height, &resumed);
+    mResize.reset();
+  }
+  if (mMaxToolbarHeight) {
+    SendMaxToolbarHeight(mMaxToolbarHeight.ref());
+    mMaxToolbarHeight.reset();
+  }
+  if (mDefaultClearColor) {
+    SendDefaultClearColor(mDefaultClearColor.ref());
+    mDefaultClearColor.reset();
+  }
+  if (mLayerUpdateEnabled) {
+    SendEnableLayerUpdateNotifications(mLayerUpdateEnabled.ref());
+    mLayerUpdateEnabled.reset();
+  }
+}
+
+#ifdef MOZ_WIDGET_ANDROID
+void UiCompositorControllerChild::SetCompositorSurfaceManager(
+    java::CompositorSurfaceManager::Param aCompositorSurfaceManager) {
+  MOZ_ASSERT(!mCompositorSurfaceManager,
+             "SetCompositorSurfaceManager must only be called once.");
+  MOZ_ASSERT(mProcessToken != 0,
+             "SetCompositorSurfaceManager must only be called for GPU process "
+             "controllers.");
+  mCompositorSurfaceManager = aCompositorSurfaceManager;
+};
+
+void UiCompositorControllerChild::OnCompositorSurfaceChanged(
+    int32_t aWidgetId, java::sdk::Surface::Param aSurface) {
+  // If mCompositorSurfaceManager is not set then there is no GPU process and
+  // we do not need to do anything.
+  if (mCompositorSurfaceManager == nullptr) {
+    return;
+  }
+
+  nsresult result =
+      mCompositorSurfaceManager->OnSurfaceChanged(aWidgetId, aSurface);
+
+  // If our remote binder has died then notify the GPU process manager.
+  if (NS_FAILED(result)) {
+    if (mProcessToken) {
+      gfx::GPUProcessManager::Get()->NotifyRemoteActorDestroyed(mProcessToken);
+      mProcessToken = 0;
+    }
+  }
+}
+#endif
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/UiCompositorControllerChild.h b/gfx/layers/ipc/UiCompositorControllerChild.h
new file mode 100644
index 0000000000..bf543ee6a3
--- /dev/null
+++ b/gfx/layers/ipc/UiCompositorControllerChild.h
@@ -0,0 +1,120 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef include_gfx_ipc_UiCompositorControllerChild_h
+#define include_gfx_ipc_UiCompositorControllerChild_h
+
+#include "mozilla/layers/PUiCompositorControllerChild.h"
+
+#include "mozilla/gfx/2D.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ipc/Shmem.h"
+#include "mozilla/layers/UiCompositorControllerParent.h"
+#include "mozilla/RefPtr.h"
+#include "nsThread.h"
+#ifdef MOZ_WIDGET_ANDROID
+#  include "SurfaceTexture.h"
+#  include "mozilla/java/CompositorSurfaceManagerWrappers.h"
+#endif
+
+class nsBaseWidget;
+
+namespace mozilla {
+namespace layers {
+
+class UiCompositorControllerChild final
+    : protected PUiCompositorControllerChild {
+  friend class PUiCompositorControllerChild;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(UiCompositorControllerChild, final)
+
+  static RefPtr<UiCompositorControllerChild> CreateForSameProcess(
+      const LayersId& aRootLayerTreeId, nsBaseWidget* aWidget);
+  static RefPtr<UiCompositorControllerChild> CreateForGPUProcess(
+      const uint64_t& aProcessToken,
+      Endpoint<PUiCompositorControllerChild>&& aEndpoint,
+      nsBaseWidget* aWidget);
+
+  bool Pause();
+  bool Resume();
+  bool ResumeAndResize(const int32_t& aX, const int32_t& aY,
+                       const int32_t& aHeight, const int32_t& aWidth);
+  bool InvalidateAndRender();
+  bool SetMaxToolbarHeight(const int32_t& aHeight);
+  bool SetFixedBottomOffset(int32_t aOffset);
+  bool ToolbarAnimatorMessageFromUI(const int32_t& aMessage);
+  bool SetDefaultClearColor(const uint32_t& aColor);
+  bool RequestScreenPixels();
+  bool EnableLayerUpdateNotifications(const bool& aEnable);
+
+  void Destroy();
+
+  bool DeallocPixelBuffer(Shmem& aMem);
+
+#ifdef MOZ_WIDGET_ANDROID
+  // Set mCompositorSurfaceManager. Must be called straight after initialization
+  // for GPU process controllers. Do not call for in-process controllers. This
+  // is separate from CreateForGPUProcess to avoid cluttering its declaration
+  // with JNI types.
+  void SetCompositorSurfaceManager(
+      java::CompositorSurfaceManager::Param aCompositorSurfaceManager);
+
+  // Send a Surface to the GPU process that a given widget ID should be
+  // composited in to. If not using a GPU process this function does nothing, as
+  // the InProcessCompositorWidget can read the Surface directly from the
+  // widget.
+  //
+  // Note that this function does not actually use the PUiCompositorController
+  // IPDL protocol, and instead uses Android's binder IPC mechanism via
+  // mCompositorSurfaceManager. It can be called from any thread.
+  void OnCompositorSurfaceChanged(int32_t aWidgetId,
+                                  java::sdk::Surface::Param aSurface);
+#endif
+
+ protected:
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  void ProcessingError(Result aCode, const char* aReason) override;
+  void HandleFatalError(const char* aMsg) override;
+  mozilla::ipc::IPCResult RecvToolbarAnimatorMessageFromCompositor(
+      const int32_t& aMessage);
+  mozilla::ipc::IPCResult RecvRootFrameMetrics(const ScreenPoint& aScrollOffset,
+                                               const CSSToScreenScale& aZoom);
+  mozilla::ipc::IPCResult RecvScreenPixels(Shmem&& aMem,
+                                           const ScreenIntSize& aSize,
+                                           bool aNeedsYFlip);
+
+ private:
+  explicit UiCompositorControllerChild(const uint64_t& aProcessToken,
+                                       nsBaseWidget* aWidget);
+  virtual ~UiCompositorControllerChild();
+  void OpenForSameProcess();
+  void OpenForGPUProcess(Endpoint<PUiCompositorControllerChild>&& aEndpoint);
+  void SendCachedValues();
+
+  bool mIsOpen;
+  uint64_t mProcessToken;
+  Maybe<gfx::IntRect> mResize;
+  Maybe<int32_t> mMaxToolbarHeight;
+  Maybe<uint32_t> mDefaultClearColor;
+  Maybe<bool> mLayerUpdateEnabled;
+  RefPtr<nsBaseWidget> mWidget;
+  // Should only be set when compositor is in process.
+  RefPtr<UiCompositorControllerParent> mParent;
+
+#ifdef MOZ_WIDGET_ANDROID
+  // Android interface to send Surfaces to the GPU process. This uses Android
+  // binder rather than IPDL because Surfaces cannot be sent via IPDL. It lives
+  // here regardless because it is a conceptually logical location, even if the
+  // underlying IPC mechanism is different.
+  // This will be null if there is no GPU process.
+  mozilla::java::CompositorSurfaceManager::GlobalRef mCompositorSurfaceManager;
+#endif
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // include_gfx_ipc_UiCompositorControllerChild_h
diff --git a/gfx/layers/ipc/UiCompositorControllerMessageTypes.h b/gfx/layers/ipc/UiCompositorControllerMessageTypes.h
new file mode 100644
index 0000000000..3e68e7be31
--- /dev/null
+++ b/gfx/layers/ipc/UiCompositorControllerMessageTypes.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef include_gfx_ipc_UiCompositorControllerMessageTypes_h
+#define include_gfx_ipc_UiCompositorControllerMessageTypes_h
+
+namespace mozilla {
+namespace layers {
+
+//
+// NOTE: These values are also defined in
+// mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoSession.java
+// and must be kept in sync. Any new message added here must also be added
+// there.
+//
+
+// clang-format off
+enum UiCompositorControllerMessageTypes {
+  FIRST_PAINT                      = 0, // Sent from compositor after first paint
+  LAYERS_UPDATED                   = 1, // Sent from the compositor when any layer has been updated
+  COMPOSITOR_CONTROLLER_OPEN       = 2, // Compositor controller IPC is open
+  IS_COMPOSITOR_CONTROLLER_OPEN    = 3  // Special message sent from controller to query if the compositor controller is open
+};
+// clang-format on
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // include_gfx_ipc_UiCompositorControllerMessageTypes_h
diff --git a/gfx/layers/ipc/UiCompositorControllerParent.cpp b/gfx/layers/ipc/UiCompositorControllerParent.cpp
new file mode 100644
index 0000000000..1e34969e84
--- /dev/null
+++ b/gfx/layers/ipc/UiCompositorControllerParent.cpp
@@ -0,0 +1,296 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "UiCompositorControllerParent.h"
+
+#if defined(MOZ_WIDGET_ANDROID)
+#  include "apz/src/APZCTreeManager.h"
+#  include "mozilla/widget/AndroidCompositorWidget.h"
+#endif
+#include <utility>
+
+#include "FrameMetrics.h"
+#include "SynchronousTask.h"
+#include "mozilla/Unused.h"
+#include "mozilla/gfx/Types.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/Compositor.h"
+#include "mozilla/layers/CompositorBridgeParent.h"
+#include "mozilla/layers/CompositorThread.h"
+#include "mozilla/layers/UiCompositorControllerMessageTypes.h"
+#include "mozilla/layers/WebRenderBridgeParent.h"
+
+namespace mozilla {
+namespace layers {
+
+typedef CompositorBridgeParent::LayerTreeState LayerTreeState;
+
+/* static */
+RefPtr<UiCompositorControllerParent>
+UiCompositorControllerParent::GetFromRootLayerTreeId(
+    const LayersId& aRootLayerTreeId) {
+  RefPtr<UiCompositorControllerParent> controller;
+  CompositorBridgeParent::CallWithIndirectShadowTree(
+      aRootLayerTreeId, [&](LayerTreeState& aState) -> void {
+        controller = aState.mUiControllerParent;
+      });
+  return controller;
+}
+
+/* static */
+RefPtr<UiCompositorControllerParent> UiCompositorControllerParent::Start(
+    const LayersId& aRootLayerTreeId,
+    Endpoint<PUiCompositorControllerParent>&& aEndpoint) {
+  RefPtr<UiCompositorControllerParent> parent =
+      new UiCompositorControllerParent(aRootLayerTreeId);
+
+  RefPtr<Runnable> task =
+      NewRunnableMethod<Endpoint<PUiCompositorControllerParent>&&>(
+          "layers::UiCompositorControllerParent::Open", parent,
+          &UiCompositorControllerParent::Open, std::move(aEndpoint));
+  CompositorThread()->Dispatch(task.forget());
+
+  return parent;
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvPause() {
+  CompositorBridgeParent* parent =
+      CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+          mRootLayerTreeId);
+  if (parent) {
+    parent->PauseComposition();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvResume(
+    bool* aOutResumed) {
+  *aOutResumed = false;
+  CompositorBridgeParent* parent =
+      CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+          mRootLayerTreeId);
+  if (parent) {
+    *aOutResumed = parent->ResumeComposition();
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvResumeAndResize(
+    const int32_t& aX, const int32_t& aY, const int32_t& aWidth,
+    const int32_t& aHeight, bool* aOutResumed) {
+  *aOutResumed = false;
+  CompositorBridgeParent* parent =
+      CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+          mRootLayerTreeId);
+  if (parent) {
+    // Front-end expects a first paint callback upon resume/resize.
+    parent->ForceIsFirstPaint();
+#if defined(MOZ_WIDGET_ANDROID)
+    parent->GetWidget()->AsAndroid()->NotifyClientSizeChanged(
+        LayoutDeviceIntSize(aWidth, aHeight));
+#endif
+    *aOutResumed = parent->ResumeCompositionAndResize(aX, aY, aWidth, aHeight);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+UiCompositorControllerParent::RecvInvalidateAndRender() {
+  CompositorBridgeParent* parent =
+      CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+          mRootLayerTreeId);
+  if (parent) {
+    parent->ScheduleComposition(wr::RenderReasons::OTHER);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvMaxToolbarHeight(
+    const int32_t& aHeight) {
+  mMaxToolbarHeight = aHeight;
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvFixedBottomOffset(
+    const int32_t& aOffset) {
+#if defined(MOZ_WIDGET_ANDROID)
+  CompositorBridgeParent* parent =
+      CompositorBridgeParent::GetCompositorBridgeParentFromLayersId(
+          mRootLayerTreeId);
+  if (parent) {
+    parent->SetFixedLayerMargins(0, aOffset);
+  }
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult UiCompositorControllerParent::RecvDefaultClearColor(
+    const uint32_t& aColor) {
+  LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(mRootLayerTreeId);
+
+  if (state && state->mWrBridge) {
+    state->mWrBridge->SetClearColor(gfx::DeviceColor::UnusualFromARGB(aColor));
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+UiCompositorControllerParent::RecvRequestScreenPixels() {
+#if defined(MOZ_WIDGET_ANDROID)
+  LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(mRootLayerTreeId);
+
+  if (state && state->mWrBridge) {
+    state->mWrBridge->RequestScreenPixels(this);
+    state->mWrBridge->ScheduleForcedGenerateFrame(wr::RenderReasons::OTHER);
+  }
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult
+UiCompositorControllerParent::RecvEnableLayerUpdateNotifications(
+    const bool& aEnable) {
+#if defined(MOZ_WIDGET_ANDROID)
+  // Layers updates are need by Robocop test which enables them
+  mCompositorLayersUpdateEnabled = aEnable;
+#endif  // defined(MOZ_WIDGET_ANDROID)
+
+  return IPC_OK();
+}
+
+void UiCompositorControllerParent::ActorDestroy(ActorDestroyReason aWhy) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  Shutdown();
+}
+
+void UiCompositorControllerParent::ToolbarAnimatorMessageFromCompositor(
+    int32_t aMessage) {
+  // This function can be call from ether compositor or controller thread.
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    CompositorThread()->Dispatch(NewRunnableMethod<int32_t>(
+        "layers::UiCompositorControllerParent::"
+        "ToolbarAnimatorMessageFromCompositor",
+        this,
+        &UiCompositorControllerParent::ToolbarAnimatorMessageFromCompositor,
+        aMessage));
+    return;
+  }
+
+  Unused << SendToolbarAnimatorMessageFromCompositor(aMessage);
+}
+
+bool UiCompositorControllerParent::AllocPixelBuffer(const int32_t aSize,
+                                                    ipc::Shmem* aMem) {
+  MOZ_ASSERT(aSize > 0);
+  return AllocShmem(aSize, aMem);
+}
+
+void UiCompositorControllerParent::NotifyLayersUpdated() {
+#ifdef MOZ_WIDGET_ANDROID
+  if (mCompositorLayersUpdateEnabled) {
+    ToolbarAnimatorMessageFromCompositor(LAYERS_UPDATED);
+  }
+#endif
+}
+
+void UiCompositorControllerParent::NotifyFirstPaint() {
+  ToolbarAnimatorMessageFromCompositor(FIRST_PAINT);
+}
+
+void UiCompositorControllerParent::NotifyUpdateScreenMetrics(
+    const GeckoViewMetrics& aMetrics) {
+#if defined(MOZ_WIDGET_ANDROID)
+  // TODO: Need to handle different x-and y-scales.
+  CSSToScreenScale scale = ViewTargetAs<ScreenPixel>(
+      aMetrics.mZoom, PixelCastJustification::ScreenIsParentLayerForRoot);
+  ScreenPoint scrollOffset = aMetrics.mVisualScrollOffset * scale;
+  CompositorThread()->Dispatch(NewRunnableMethod<ScreenPoint, CSSToScreenScale>(
+      "UiCompositorControllerParent::SendRootFrameMetrics", this,
+      &UiCompositorControllerParent::SendRootFrameMetrics, scrollOffset,
+      scale));
+#endif
+}
+
+UiCompositorControllerParent::UiCompositorControllerParent(
+    const LayersId& aRootLayerTreeId)
+    : mRootLayerTreeId(aRootLayerTreeId)
+#ifdef MOZ_WIDGET_ANDROID
+      ,
+      mCompositorLayersUpdateEnabled(false)
+#endif
+      ,
+      mMaxToolbarHeight(0) {
+  MOZ_COUNT_CTOR(UiCompositorControllerParent);
+}
+
+UiCompositorControllerParent::~UiCompositorControllerParent() {
+  MOZ_COUNT_DTOR(UiCompositorControllerParent);
+}
+
+void UiCompositorControllerParent::InitializeForSameProcess() {
+  // This function is called by UiCompositorControllerChild in the main thread.
+  // So dispatch to the compositor thread to Initialize.
+  if (!CompositorThreadHolder::IsInCompositorThread()) {
+    SetOtherProcessId(base::GetCurrentProcId());
+    SynchronousTask task(
+        "UiCompositorControllerParent::InitializeForSameProcess");
+
+    CompositorThread()->Dispatch(NS_NewRunnableFunction(
+        "UiCompositorControllerParent::InitializeForSameProcess", [&]() {
+          AutoCompleteTask complete(&task);
+          InitializeForSameProcess();
+        }));
+
+    task.Wait();
+    return;
+  }
+
+  Initialize();
+}
+
+void UiCompositorControllerParent::InitializeForOutOfProcess() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  Initialize();
+}
+
+void UiCompositorControllerParent::Initialize() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(mRootLayerTreeId);
+  MOZ_ASSERT(state);
+  MOZ_ASSERT(state->mParent);
+  if (!state || !state->mParent) {
+    return;
+  }
+  state->mUiControllerParent = this;
+}
+
+void UiCompositorControllerParent::Open(
+    Endpoint<PUiCompositorControllerParent>&& aEndpoint) {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  if (!aEndpoint.Bind(this)) {
+    // We can't recover from this.
+    MOZ_CRASH("Failed to bind UiCompositorControllerParent to endpoint");
+  }
+  InitializeForOutOfProcess();
+}
+
+void UiCompositorControllerParent::Shutdown() {
+  MOZ_ASSERT(CompositorThreadHolder::IsInCompositorThread());
+  LayerTreeState* state =
+      CompositorBridgeParent::GetIndirectShadowTree(mRootLayerTreeId);
+  if (state) {
+    state->mUiControllerParent = nullptr;
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/UiCompositorControllerParent.h b/gfx/layers/ipc/UiCompositorControllerParent.h
new file mode 100644
index 0000000000..e6284e7dfb
--- /dev/null
+++ b/gfx/layers/ipc/UiCompositorControllerParent.h
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef include_gfx_ipc_UiCompositorControllerParent_h
+#define include_gfx_ipc_UiCompositorControllerParent_h
+
+#include "mozilla/layers/PUiCompositorControllerParent.h"
+#include "mozilla/layers/APZUtils.h"
+#include "mozilla/ipc/Shmem.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+namespace layers {
+
+struct FrameMetrics;
+
+class UiCompositorControllerParent final
+    : public PUiCompositorControllerParent {
+  // UiCompositorControllerChild needs to call the private constructor when
+  // running in process.
+  friend class UiCompositorControllerChild;
+
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(UiCompositorControllerParent, final)
+
+  static RefPtr<UiCompositorControllerParent> GetFromRootLayerTreeId(
+      const LayersId& aRootLayerTreeId);
+  static RefPtr<UiCompositorControllerParent> Start(
+      const LayersId& aRootLayerTreeId,
+      Endpoint<PUiCompositorControllerParent>&& aEndpoint);
+
+  // PUiCompositorControllerParent functions
+  mozilla::ipc::IPCResult RecvPause();
+  mozilla::ipc::IPCResult RecvResume(bool* aOutResumed);
+  mozilla::ipc::IPCResult RecvResumeAndResize(const int32_t& aX,
+                                              const int32_t& aY,
+                                              const int32_t& aHeight,
+                                              const int32_t& aWidth,
+                                              bool* aOutResumed);
+  mozilla::ipc::IPCResult RecvInvalidateAndRender();
+  mozilla::ipc::IPCResult RecvMaxToolbarHeight(const int32_t& aHeight);
+  mozilla::ipc::IPCResult RecvFixedBottomOffset(const int32_t& aOffset);
+  mozilla::ipc::IPCResult RecvDefaultClearColor(const uint32_t& aColor);
+  mozilla::ipc::IPCResult RecvRequestScreenPixels();
+  mozilla::ipc::IPCResult RecvEnableLayerUpdateNotifications(
+      const bool& aEnable);
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // Class specific functions
+  void ToolbarAnimatorMessageFromCompositor(int32_t aMessage);
+  bool AllocPixelBuffer(const int32_t aSize, Shmem* aMem);
+
+  // Called when a layer has been updated so the UI thread may be notified if
+  // necessary.
+  void NotifyLayersUpdated();
+  void NotifyFirstPaint();
+  void NotifyUpdateScreenMetrics(const GeckoViewMetrics& aMetrics);
+
+ private:
+  explicit UiCompositorControllerParent(const LayersId& aRootLayerTreeId);
+  virtual ~UiCompositorControllerParent();
+  void InitializeForSameProcess();
+  void InitializeForOutOfProcess();
+  void Initialize();
+  void Open(Endpoint<PUiCompositorControllerParent>&& aEndpoint);
+  void Shutdown();
+
+  LayersId mRootLayerTreeId;
+
+#if defined(MOZ_WIDGET_ANDROID)
+  bool mCompositorLayersUpdateEnabled;  // Flag set to true when the UI thread
+                                        // is expecting to be notified when a
+                                        // layer has been updated
+#endif                                  // defined(MOZ_WIDGET_ANDROID)
+
+  int32_t mMaxToolbarHeight;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // include_gfx_ipc_UiCompositorControllerParent_h
diff --git a/gfx/layers/ipc/VideoBridgeChild.cpp b/gfx/layers/ipc/VideoBridgeChild.cpp
new file mode 100644
index 0000000000..c2d5f2ec25
--- /dev/null
+++ b/gfx/layers/ipc/VideoBridgeChild.cpp
@@ -0,0 +1,188 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "VideoBridgeChild.h"
+#include "VideoBridgeParent.h"
+#include "CompositorThread.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/StaticMutex.h"
+#include "transport/runnable_utils.h"
+#include "SynchronousTask.h"
+
+namespace mozilla {
+namespace layers {
+
+// Singleton
+static StaticMutex sVideoBridgeLock MOZ_UNANNOTATED;
+StaticRefPtr<VideoBridgeChild> sVideoBridge;
+
+/* static */
+void VideoBridgeChild::StartupForGPUProcess() {
+  ipc::Endpoint<PVideoBridgeParent> parentPipe;
+  ipc::Endpoint<PVideoBridgeChild> childPipe;
+
+  PVideoBridge::CreateEndpoints(base::GetCurrentProcId(),
+                                base::GetCurrentProcId(), &parentPipe,
+                                &childPipe);
+
+  VideoBridgeChild::Open(std::move(childPipe));
+  VideoBridgeParent::Open(std::move(parentPipe), VideoBridgeSource::GpuProcess);
+}
+
+/* static */
+void VideoBridgeChild::Open(Endpoint<PVideoBridgeChild>&& aEndpoint) {
+  StaticMutexAutoLock lock(sVideoBridgeLock);
+  MOZ_ASSERT(!sVideoBridge || !sVideoBridge->CanSend());
+  sVideoBridge = new VideoBridgeChild();
+
+  if (!aEndpoint.Bind(sVideoBridge)) {
+    // We can't recover from this.
+    MOZ_CRASH("Failed to bind VideoBridgeChild to endpoint");
+  }
+}
+
+/* static */
+void VideoBridgeChild::Shutdown() {
+  StaticMutexAutoLock lock(sVideoBridgeLock);
+  if (sVideoBridge) {
+    sVideoBridge->Close();
+    sVideoBridge = nullptr;
+  }
+}
+
+VideoBridgeChild::VideoBridgeChild()
+    : mThread(GetCurrentSerialEventTarget()), mCanSend(true) {}
+
+VideoBridgeChild::~VideoBridgeChild() = default;
+
+VideoBridgeChild* VideoBridgeChild::GetSingleton() {
+  StaticMutexAutoLock lock(sVideoBridgeLock);
+  return sVideoBridge;
+}
+
+bool VideoBridgeChild::AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) {
+  if (!mThread->IsOnCurrentThread()) {
+    return DispatchAllocShmemInternal(aSize, aShmem, true);  // true: unsafe
+  }
+
+  if (!CanSend()) {
+    return false;
+  }
+
+  return PVideoBridgeChild::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool VideoBridgeChild::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  MOZ_ASSERT(CanSend());
+  return PVideoBridgeChild::AllocShmem(aSize, aShmem);
+}
+
+void VideoBridgeChild::ProxyAllocShmemNow(SynchronousTask* aTask, size_t aSize,
+                                          ipc::Shmem* aShmem, bool aUnsafe,
+                                          bool* aSuccess) {
+  AutoCompleteTask complete(aTask);
+
+  if (!CanSend()) {
+    return;
+  }
+
+  bool ok = false;
+  if (aUnsafe) {
+    ok = AllocUnsafeShmem(aSize, aShmem);
+  } else {
+    ok = AllocShmem(aSize, aShmem);
+  }
+  *aSuccess = ok;
+}
+
+bool VideoBridgeChild::DispatchAllocShmemInternal(size_t aSize,
+                                                  ipc::Shmem* aShmem,
+                                                  bool aUnsafe) {
+  SynchronousTask task("AllocatorProxy alloc");
+
+  bool success = false;
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<VideoBridgeChild>(this), &VideoBridgeChild::ProxyAllocShmemNow,
+      &task, aSize, aShmem, aUnsafe, &success);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+
+  return success;
+}
+
+void VideoBridgeChild::ProxyDeallocShmemNow(SynchronousTask* aTask,
+                                            ipc::Shmem* aShmem, bool* aResult) {
+  AutoCompleteTask complete(aTask);
+
+  if (!CanSend()) {
+    return;
+  }
+  *aResult = DeallocShmem(*aShmem);
+}
+
+bool VideoBridgeChild::DeallocShmem(ipc::Shmem& aShmem) {
+  if (GetThread()->IsOnCurrentThread()) {
+    if (!CanSend()) {
+      return false;
+    }
+    return PVideoBridgeChild::DeallocShmem(aShmem);
+  }
+
+  SynchronousTask task("AllocatorProxy Dealloc");
+  bool result = false;
+
+  RefPtr<Runnable> runnable = WrapRunnable(
+      RefPtr<VideoBridgeChild>(this), &VideoBridgeChild::ProxyDeallocShmemNow,
+      &task, &aShmem, &result);
+  GetThread()->Dispatch(runnable.forget());
+
+  task.Wait();
+  return result;
+}
+
+PTextureChild* VideoBridgeChild::AllocPTextureChild(
+    const SurfaceDescriptor&, ReadLockDescriptor&, const LayersBackend&,
+    const TextureFlags&, const dom::ContentParentId& aContentId,
+    const uint64_t& aSerial) {
+  MOZ_ASSERT(CanSend());
+  return TextureClient::CreateIPDLActor();
+}
+
+bool VideoBridgeChild::DeallocPTextureChild(PTextureChild* actor) {
+  return TextureClient::DestroyIPDLActor(actor);
+}
+
+void VideoBridgeChild::ActorDestroy(ActorDestroyReason aWhy) {
+  mCanSend = false;
+}
+
+PTextureChild* VideoBridgeChild::CreateTexture(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+    LayersBackend aLayersBackend, TextureFlags aFlags,
+    const dom::ContentParentId& aContentId, uint64_t aSerial,
+    wr::MaybeExternalImageId& aExternalImageId) {
+  MOZ_ASSERT(CanSend());
+  return SendPTextureConstructor(aSharedData, std::move(aReadLock),
+                                 aLayersBackend, aFlags, aContentId, aSerial);
+}
+
+bool VideoBridgeChild::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void VideoBridgeChild::HandleFatalError(const char* aMsg) {
+  dom::ContentChild::FatalErrorIfNotUsingGPUProcess(aMsg, OtherPid());
+}
+
+mozilla::ipc::IPCResult VideoBridgeChild::RecvPing(PingResolver&& aResolver) {
+  aResolver(void_t{});
+  return IPC_OK();
+}
+
+}  // namespace layers
+}  // namespace mozilla
diff --git a/gfx/layers/ipc/VideoBridgeChild.h b/gfx/layers/ipc/VideoBridgeChild.h
new file mode 100644
index 0000000000..b72289e4b6
--- /dev/null
+++ b/gfx/layers/ipc/VideoBridgeChild.h
@@ -0,0 +1,90 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_GFX_VIDEOBRIDGECHILD_H
+#define MOZILLA_GFX_VIDEOBRIDGECHILD_H
+
+#include "mozilla/layers/PVideoBridgeChild.h"
+#include "mozilla/layers/VideoBridgeUtils.h"
+#include "ISurfaceAllocator.h"
+#include "TextureForwarder.h"
+
+namespace mozilla {
+namespace layers {
+
+class SynchronousTask;
+
+class VideoBridgeChild final : public PVideoBridgeChild,
+                               public TextureForwarder {
+ public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VideoBridgeChild, override);
+
+  static void StartupForGPUProcess();
+  static void Shutdown();
+
+  static VideoBridgeChild* GetSingleton();
+
+  // PVideoBridgeChild
+  PTextureChild* AllocPTextureChild(const SurfaceDescriptor& aSharedData,
+                                    ReadLockDescriptor& aReadLock,
+                                    const LayersBackend& aLayersBackend,
+                                    const TextureFlags& aFlags,
+                                    const dom::ContentParentId& aContentId,
+                                    const uint64_t& aSerial);
+  bool DeallocPTextureChild(PTextureChild* actor);
+
+  mozilla::ipc::IPCResult RecvPing(PingResolver&& aResolver);
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // ISurfaceAllocator
+  bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+  bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+  // TextureForwarder
+  PTextureChild* CreateTexture(
+      const SurfaceDescriptor& aSharedData, ReadLockDescriptor&& aReadLock,
+      LayersBackend aLayersBackend, TextureFlags aFlags,
+      const dom::ContentParentId& aContentId, uint64_t aSerial,
+      wr::MaybeExternalImageId& aExternalImageId) override;
+
+  // ClientIPCAllocator
+  base::ProcessId GetParentPid() const override { return OtherPid(); }
+  nsISerialEventTarget* GetThread() const override { return mThread; }
+  void CancelWaitForNotifyNotUsed(uint64_t aTextureId) override {
+    MOZ_ASSERT(false, "NO RECYCLING HERE");
+  }
+
+  // ISurfaceAllocator
+  bool IsSameProcess() const override;
+
+  bool CanSend() { return mCanSend; }
+
+  static void Open(Endpoint<PVideoBridgeChild>&& aEndpoint);
+
+ protected:
+  void HandleFatalError(const char* aMsg) override;
+  bool DispatchAllocShmemInternal(size_t aSize, mozilla::ipc::Shmem* aShmem,
+                                  bool aUnsafe);
+  void ProxyAllocShmemNow(SynchronousTask* aTask, size_t aSize,
+                          mozilla::ipc::Shmem* aShmem, bool aUnsafe,
+                          bool* aSuccess);
+  void ProxyDeallocShmemNow(SynchronousTask* aTask, mozilla::ipc::Shmem* aShmem,
+                            bool* aResult);
+
+ private:
+  VideoBridgeChild();
+  virtual ~VideoBridgeChild();
+
+  nsCOMPtr<nsISerialEventTarget> mThread;
+  bool mCanSend;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif
diff --git a/gfx/layers/ipc/VideoBridgeParent.cpp b/gfx/layers/ipc/VideoBridgeParent.cpp
new file mode 100644
index 0000000000..6413c27bc1
--- /dev/null
+++ b/gfx/layers/ipc/VideoBridgeParent.cpp
@@ -0,0 +1,321 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "VideoBridgeParent.h"
+#include "CompositorThread.h"
+#include "mozilla/DataMutex.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/layers/TextureHost.h"
+#include "mozilla/layers/VideoBridgeUtils.h"
+#include "mozilla/webrender/RenderThread.h"
+
+namespace mozilla::layers {
+
+using namespace mozilla::ipc;
+using namespace mozilla::gfx;
+
+using VideoBridgeTable =
+    EnumeratedArray<VideoBridgeSource, VideoBridgeSource::_Count,
+                    VideoBridgeParent*>;
+
+static StaticDataMutex<VideoBridgeTable> sVideoBridgeFromProcess(
+    "VideoBridges");
+static Atomic<bool> sVideoBridgeParentShutDown(false);
+
+VideoBridgeParent::VideoBridgeParent(VideoBridgeSource aSource)
+    : mMonitor("VideoBridgeParent::mMonitor"),
+      mCompositorThreadHolder(CompositorThreadHolder::GetSingleton()),
+      mClosed(false) {
+  auto videoBridgeFromProcess = sVideoBridgeFromProcess.Lock();
+  switch (aSource) {
+    case VideoBridgeSource::RddProcess:
+    case VideoBridgeSource::GpuProcess:
+    case VideoBridgeSource::MFMediaEngineCDMProcess:
+      (*videoBridgeFromProcess)[aSource] = this;
+      break;
+    default:
+      MOZ_CRASH("Unhandled case");
+  }
+}
+
+VideoBridgeParent::~VideoBridgeParent() {
+  auto videoBridgeFromProcess = sVideoBridgeFromProcess.Lock();
+  for (auto& bridgeParent : *videoBridgeFromProcess) {
+    if (bridgeParent == this) {
+      bridgeParent = nullptr;
+    }
+  }
+}
+
+/* static */
+void VideoBridgeParent::Open(Endpoint<PVideoBridgeParent>&& aEndpoint,
+                             VideoBridgeSource aSource) {
+  RefPtr<VideoBridgeParent> parent = new VideoBridgeParent(aSource);
+
+  CompositorThread()->Dispatch(
+      NewRunnableMethod<Endpoint<PVideoBridgeParent>&&>(
+          "gfx::layers::VideoBridgeParent::Bind", parent,
+          &VideoBridgeParent::Bind, std::move(aEndpoint)));
+}
+
+void VideoBridgeParent::Bind(Endpoint<PVideoBridgeParent>&& aEndpoint) {
+  if (!aEndpoint.Bind(this)) {
+    // We can't recover from this.
+    MOZ_CRASH("Failed to bind VideoBridgeParent to endpoint");
+  }
+}
+
+/* static */
+RefPtr<VideoBridgeParent> VideoBridgeParent::GetSingleton(
+    const Maybe<VideoBridgeSource>& aSource) {
+  MOZ_ASSERT(aSource.isSome());
+  auto videoBridgeFromProcess = sVideoBridgeFromProcess.Lock();
+  switch (aSource.value()) {
+    case VideoBridgeSource::RddProcess:
+    case VideoBridgeSource::GpuProcess:
+    case VideoBridgeSource::MFMediaEngineCDMProcess:
+      MOZ_ASSERT((*videoBridgeFromProcess)[aSource.value()]);
+      return RefPtr{(*videoBridgeFromProcess)[aSource.value()]};
+    default:
+      MOZ_CRASH("Unhandled case");
+  }
+}
+
+already_AddRefed<TextureHost> VideoBridgeParent::LookupTextureAsync(
+    const dom::ContentParentId& aContentId, uint64_t aSerial) {
+  MonitorAutoLock lock(mMonitor);
+
+  // We raced shutting down the actor.
+  if (NS_WARN_IF(!mCompositorThreadHolder)) {
+    MOZ_ASSERT_UNREACHABLE("Called on destroyed VideoBridgeParent actor!");
+    return nullptr;
+  }
+
+  MOZ_ASSERT(mCompositorThreadHolder->IsInThread());
+
+  auto* actor = mTextureMap[aSerial];
+  if (NS_WARN_IF(!actor)) {
+    return nullptr;
+  }
+
+  if (NS_WARN_IF(aContentId != TextureHost::GetTextureContentId(actor))) {
+    return nullptr;
+  }
+
+  return do_AddRef(TextureHost::AsTextureHost(actor));
+}
+
+already_AddRefed<TextureHost> VideoBridgeParent::LookupTexture(
+    const dom::ContentParentId& aContentId, uint64_t aSerial) {
+  MonitorAutoLock lock(mMonitor);
+
+  // We raced shutting down the actor.
+  if (NS_WARN_IF(!mCompositorThreadHolder)) {
+    return nullptr;
+  }
+
+  auto* actor = mTextureMap[aSerial];
+  if (actor) {
+    if (NS_WARN_IF(aContentId != TextureHost::GetTextureContentId(actor))) {
+      return nullptr;
+    }
+    return do_AddRef(TextureHost::AsTextureHost(actor));
+  }
+
+  // We cannot block on the Compositor thread because that is the thread we get
+  // the IPC calls for the update on.
+  if (NS_WARN_IF(mCompositorThreadHolder->IsInThread())) {
+    MOZ_ASSERT_UNREACHABLE("Should never call on Compositor thread!");
+    return nullptr;
+  }
+
+  // Canvas may have raced ahead of VideoBridgeParent setting up the
+  // PTextureParent IPDL object. This should happen only rarely/briefly. Since
+  // we know that the PTexture constructor must be in the send queue, we can
+  // block until the IPDL ping comes back.
+  bool complete = false;
+
+  auto resolve = [&](void_t&&) {
+    MonitorAutoLock lock(mMonitor);
+    complete = true;
+    lock.NotifyAll();
+  };
+
+  auto reject = [&](ipc::ResponseRejectReason) {
+    MonitorAutoLock lock(mMonitor);
+    complete = true;
+    lock.NotifyAll();
+  };
+
+  mCompositorThreadHolder->Dispatch(
+      NS_NewRunnableFunction("VideoBridgeParent::LookupTexture", [&]() {
+        if (CanSend()) {
+          SendPing(std::move(resolve), std::move(reject));
+        } else {
+          reject(ipc::ResponseRejectReason::ChannelClosed);
+        }
+      }));
+
+  while (!complete) {
+    lock.Wait();
+  }
+
+  actor = mTextureMap[aSerial];
+  if (!actor) {
+    return nullptr;
+  }
+
+  if (NS_WARN_IF(aContentId != TextureHost::GetTextureContentId(actor))) {
+    return nullptr;
+  }
+
+  return do_AddRef(TextureHost::AsTextureHost(actor));
+}
+
+void VideoBridgeParent::ActorDestroy(ActorDestroyReason aWhy) {
+  bool shutdown = sVideoBridgeParentShutDown;
+
+  if (!shutdown && aWhy == AbnormalShutdown) {
+    gfxCriticalNote
+        << "VideoBridgeParent receives IPC close with reason=AbnormalShutdown";
+  }
+
+  {
+    MonitorAutoLock lock(mMonitor);
+    // Can't alloc/dealloc shmems from now on.
+    mClosed = true;
+    mCompositorThreadHolder = nullptr;
+  }
+}
+
+/* static */
+void VideoBridgeParent::Shutdown() {
+  CompositorThread()->Dispatch(NS_NewRunnableFunction(
+      "VideoBridgeParent::Shutdown",
+      []() -> void { VideoBridgeParent::ShutdownInternal(); }));
+}
+
+/* static */
+void VideoBridgeParent::ShutdownInternal() {
+  sVideoBridgeParentShutDown = true;
+
+  nsTArray<RefPtr<VideoBridgeParent>> bridges;
+
+  // We don't want to hold the sVideoBridgeFromProcess lock when the
+  // VideoBridgeParent objects are closed without holding a reference to them.
+  {
+    auto videoBridgeFromProcess = sVideoBridgeFromProcess.Lock();
+    for (auto& bridgeParent : *videoBridgeFromProcess) {
+      if (bridgeParent) {
+        bridges.AppendElement(bridgeParent);
+      }
+    }
+  }
+
+  for (auto& bridge : bridges) {
+    bridge->Close();
+  }
+}
+
+/* static */
+void VideoBridgeParent::UnregisterExternalImages() {
+  MOZ_ASSERT(sVideoBridgeParentShutDown);
+
+  auto videoBridgeFromProcess = sVideoBridgeFromProcess.Lock();
+  for (auto& bridgeParent : *videoBridgeFromProcess) {
+    if (bridgeParent) {
+      bridgeParent->DoUnregisterExternalImages();
+    }
+  }
+}
+
+void VideoBridgeParent::DoUnregisterExternalImages() {
+  const ManagedContainer<PTextureParent>& textures = ManagedPTextureParent();
+  for (const auto& key : textures) {
+    RefPtr<TextureHost> texture = TextureHost::AsTextureHost(key);
+
+    if (texture) {
+      texture->MaybeDestroyRenderTexture();
+    }
+  }
+}
+
+PTextureParent* VideoBridgeParent::AllocPTextureParent(
+    const SurfaceDescriptor& aSharedData, ReadLockDescriptor& aReadLock,
+    const LayersBackend& aLayersBackend, const TextureFlags& aFlags,
+    const dom::ContentParentId& aContentId, const uint64_t& aSerial) {
+  PTextureParent* parent = TextureHost::CreateIPDLActor(
+      this, aSharedData, std::move(aReadLock), aLayersBackend, aFlags,
+      aContentId, aSerial, Nothing());
+
+  if (!parent) {
+    return nullptr;
+  }
+
+  MonitorAutoLock lock(mMonitor);
+  mTextureMap[aSerial] = parent;
+  return parent;
+}
+
+bool VideoBridgeParent::DeallocPTextureParent(PTextureParent* actor) {
+  MonitorAutoLock lock(mMonitor);
+  mTextureMap.erase(TextureHost::GetTextureSerial(actor));
+  return TextureHost::DestroyIPDLActor(actor);
+}
+
+void VideoBridgeParent::SendAsyncMessage(
+    const nsTArray<AsyncParentMessageData>& aMessage) {
+  MOZ_ASSERT(false, "AsyncMessages not supported");
+}
+
+bool VideoBridgeParent::AllocShmem(size_t aSize, ipc::Shmem* aShmem) {
+  {
+    MonitorAutoLock lock(mMonitor);
+    if (mClosed) {
+      return false;
+    }
+  }
+  return PVideoBridgeParent::AllocShmem(aSize, aShmem);
+}
+
+bool VideoBridgeParent::AllocUnsafeShmem(size_t aSize, ipc::Shmem* aShmem) {
+  {
+    MonitorAutoLock lock(mMonitor);
+    if (mClosed) {
+      return false;
+    }
+  }
+  return PVideoBridgeParent::AllocUnsafeShmem(aSize, aShmem);
+}
+
+bool VideoBridgeParent::DeallocShmem(ipc::Shmem& aShmem) {
+  {
+    MonitorAutoLock lock(mMonitor);
+    if (mCompositorThreadHolder && !mCompositorThreadHolder->IsInThread()) {
+      mCompositorThreadHolder->Dispatch(NS_NewRunnableFunction(
+          "gfx::layers::VideoBridgeParent::DeallocShmem",
+          [self = RefPtr{this}, shmem = std::move(aShmem)]() mutable {
+            self->DeallocShmem(shmem);
+          }));
+      return true;
+    }
+
+    if (mClosed) {
+      return false;
+    }
+  }
+
+  return PVideoBridgeParent::DeallocShmem(aShmem);
+}
+
+bool VideoBridgeParent::IsSameProcess() const {
+  return OtherPid() == base::GetCurrentProcId();
+}
+
+void VideoBridgeParent::NotifyNotUsed(PTextureParent* aTexture,
+                                      uint64_t aTransactionId) {}
+
+}  // namespace mozilla::layers
diff --git a/gfx/layers/ipc/VideoBridgeParent.h b/gfx/layers/ipc/VideoBridgeParent.h
new file mode 100644
index 0000000000..7a062a77d3
--- /dev/null
+++ b/gfx/layers/ipc/VideoBridgeParent.h
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef gfx_layers_ipc_VideoBridgeParent_h_
+#define gfx_layers_ipc_VideoBridgeParent_h_
+
+#include "mozilla/Monitor.h"
+#include "mozilla/layers/ISurfaceAllocator.h"
+#include "mozilla/layers/PVideoBridgeParent.h"
+
+namespace mozilla::layers {
+
+enum class VideoBridgeSource : uint8_t;
+class CompositorThreadHolder;
+
+class VideoBridgeParent final : public PVideoBridgeParent,
+                                public HostIPCAllocator,
+                                public mozilla::ipc::IShmemAllocator {
+ public:
+  NS_INLINE_DECL_REFCOUNTING_INHERITED(VideoBridgeParent, HostIPCAllocator)
+
+  static RefPtr<VideoBridgeParent> GetSingleton(
+      const Maybe<VideoBridgeSource>& aSource);
+
+  static void Open(Endpoint<PVideoBridgeParent>&& aEndpoint,
+                   VideoBridgeSource aSource);
+  static void Shutdown();
+  static void UnregisterExternalImages();
+
+  already_AddRefed<TextureHost> LookupTextureAsync(
+      const dom::ContentParentId& aContentId, uint64_t aSerial);
+  already_AddRefed<TextureHost> LookupTexture(
+      const dom::ContentParentId& aContentId, uint64_t aSerial);
+
+  // PVideoBridgeParent
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  PTextureParent* AllocPTextureParent(const SurfaceDescriptor& aSharedData,
+                                      ReadLockDescriptor& aReadLock,
+                                      const LayersBackend& aLayersBackend,
+                                      const TextureFlags& aFlags,
+                                      const dom::ContentParentId& aContentId,
+                                      const uint64_t& aSerial);
+  bool DeallocPTextureParent(PTextureParent* actor);
+
+  // HostIPCAllocator
+  base::ProcessId GetChildProcessId() override { return OtherPid(); }
+  void NotifyNotUsed(PTextureParent* aTexture,
+                     uint64_t aTransactionId) override;
+  void SendAsyncMessage(
+      const nsTArray<AsyncParentMessageData>& aMessage) override;
+
+  // ISurfaceAllocator
+  IShmemAllocator* AsShmemAllocator() override { return this; }
+  bool IsSameProcess() const override;
+  bool IPCOpen() const override { return !mClosed; }
+
+  // IShmemAllocator
+  bool AllocShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+
+  bool AllocUnsafeShmem(size_t aSize, mozilla::ipc::Shmem* aShmem) override;
+
+  bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+ private:
+  ~VideoBridgeParent();
+
+  explicit VideoBridgeParent(VideoBridgeSource aSource);
+  void Bind(Endpoint<PVideoBridgeParent>&& aEndpoint);
+  static void ShutdownInternal();
+
+  void DoUnregisterExternalImages();
+
+  Monitor mMonitor;
+  RefPtr<CompositorThreadHolder> mCompositorThreadHolder
+      MOZ_GUARDED_BY(mMonitor);
+  std::map<uint64_t, PTextureParent*> mTextureMap MOZ_GUARDED_BY(mMonitor);
+  bool mClosed;
+};
+
+}  // namespace mozilla::layers
+
+#endif  // gfx_layers_ipc_VideoBridgeParent_h_
diff --git a/gfx/layers/ipc/VideoBridgeUtils.h b/gfx/layers/ipc/VideoBridgeUtils.h
new file mode 100644
index 0000000000..4163b5e08f
--- /dev/null
+++ b/gfx/layers/ipc/VideoBridgeUtils.h
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef IPC_VideoBridgeUtils_h
+#define IPC_VideoBridgeUtils_h
+
+#include "ipc/EnumSerializer.h"
+
+namespace mozilla {
+namespace layers {
+
+enum class VideoBridgeSource : uint8_t {
+  RddProcess,
+  GpuProcess,
+  MFMediaEngineCDMProcess,
+  _Count,
+};
+
+typedef Maybe<VideoBridgeSource> MaybeVideoBridgeSource;
+
+}  // namespace layers
+}  // namespace mozilla
+
+namespace IPC {
+
+template <>
+struct ParamTraits<mozilla::layers::VideoBridgeSource>
+    : public ContiguousEnumSerializer<
+          mozilla::layers::VideoBridgeSource,
+          mozilla::layers::VideoBridgeSource::RddProcess,
+          mozilla::layers::VideoBridgeSource::_Count> {};
+
+}  // namespace IPC
+
+#endif  // IPC_VideoBridgeUtils_h
diff --git a/gfx/layers/ipc/WebRenderMessages.ipdlh b/gfx/layers/ipc/WebRenderMessages.ipdlh
new file mode 100644
index 0000000000..e257346387
--- /dev/null
+++ b/gfx/layers/ipc/WebRenderMessages.ipdlh
@@ -0,0 +1,199 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=8 et :
+ */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+include "mozilla/layers/LayersMessageUtils.h";
+include "mozilla/layers/WebRenderMessageUtils.h";
+
+include LayersSurfaces;
+include LayersMessages;
+include protocol PTexture;
+
+using mozilla::layers::CompositableHandle from "mozilla/layers/LayersTypes.h";
+using mozilla::layers::CompositableHandleOwner from "mozilla/layers/LayersTypes.h";
+using mozilla::wr::LayoutSize from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::ImageDescriptor from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::ImageRendering from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::MixBlendMode from "mozilla/webrender/webrender_ffi.h";
+using mozilla::wr::ExternalImageId from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::MaybeFontInstanceOptions from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::MaybeFontInstancePlatformOptions from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::FontInstanceKey from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::FontKey from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::ImageKey from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::BlobImageKey from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::WrRotation from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::wr::PipelineId from "mozilla/webrender/WebRenderTypes.h";
+using mozilla::gfx::MaybeIntSize from "mozilla/gfx/Point.h";
+using mozilla::LayoutDeviceRect from "Units.h";
+using mozilla::LayoutDeviceSize from "Units.h";
+using mozilla::ImageIntRect from "Units.h";
+using mozilla::gfx::Rect from "mozilla/gfx/Rect.h";
+using mozilla::gfx::Matrix4x4 from "mozilla/gfx/Matrix.h";
+using struct mozilla::void_t from "mozilla/ipc/IPCCore.h";
+
+namespace mozilla {
+namespace layers {
+
+struct RefCountedShmem {
+  Shmem buffer;
+};
+
+struct OpAddSharedExternalImage {
+  ExternalImageId externalImageId;
+  ImageKey key;
+};
+
+struct OpPushExternalImageForTexture {
+  ExternalImageId externalImageId;
+  ImageKey key;
+  PTexture texture;
+  bool isUpdate;
+};
+
+struct OpAddCompositorAnimations {
+  CompositorAnimations data;
+};
+
+struct OpAddPipelineIdForCompositable {
+  PipelineId pipelineId;
+  CompositableHandle handle;
+  CompositableHandleOwner owner;
+};
+
+struct OpRemovePipelineIdForCompositable {
+  PipelineId pipelineId;
+};
+
+struct OpReleaseTextureOfImage {
+  ImageKey key;
+};
+
+struct OpUpdateAsyncImagePipeline {
+  PipelineId pipelineId;
+  LayoutDeviceRect scBounds;
+  WrRotation rotation;
+  ImageRendering filter;
+  MixBlendMode mixBlendMode;
+};
+
+struct OpUpdatedAsyncImagePipeline {
+  PipelineId pipelineId;
+};
+
+union WebRenderParentCommand {
+  OpAddPipelineIdForCompositable;
+  OpRemovePipelineIdForCompositable;
+  OpReleaseTextureOfImage;
+  OpUpdateAsyncImagePipeline;
+  OpUpdatedAsyncImagePipeline;
+  CompositableOperation;
+  OpAddCompositorAnimations;
+};
+
+struct OffsetRange {
+  uint32_t source;
+  uint32_t start;
+  uint32_t length;
+};
+
+struct OpAddImage {
+  ImageDescriptor descriptor;
+  OffsetRange bytes;
+  uint16_t tiling;
+  ImageKey key;
+};
+
+struct OpAddBlobImage {
+  ImageDescriptor descriptor;
+  OffsetRange bytes;
+  ImageIntRect visibleRect;
+  uint16_t tiling;
+  BlobImageKey key;
+};
+
+struct OpUpdateImage {
+  ImageDescriptor descriptor;
+  OffsetRange bytes;
+  ImageKey key;
+};
+
+struct OpUpdateBlobImage {
+  ImageDescriptor descriptor;
+  OffsetRange bytes;
+  BlobImageKey key;
+  ImageIntRect visibleRect;
+  ImageIntRect dirtyRect;
+};
+
+struct OpSetBlobImageVisibleArea {
+  ImageIntRect area;
+  BlobImageKey key;
+};
+
+struct OpUpdateSharedExternalImage {
+  ExternalImageId externalImageId;
+  ImageKey key;
+  ImageIntRect dirtyRect;
+};
+
+struct OpDeleteImage {
+  ImageKey key;
+};
+
+struct OpDeleteBlobImage {
+  BlobImageKey key;
+};
+
+struct OpAddRawFont {
+  OffsetRange bytes;
+  uint32_t fontIndex;
+  FontKey key;
+};
+
+struct OpAddFontDescriptor {
+  OffsetRange bytes;
+  uint32_t fontIndex;
+  FontKey key;
+};
+
+struct OpDeleteFont {
+  FontKey key;
+};
+
+struct OpAddFontInstance {
+  MaybeFontInstanceOptions options;
+  MaybeFontInstancePlatformOptions platformOptions;
+  OffsetRange variations;
+  FontInstanceKey instanceKey;
+  FontKey fontKey;
+  float glyphSize;
+};
+
+struct OpDeleteFontInstance {
+  FontInstanceKey key;
+};
+
+union OpUpdateResource {
+  OpAddImage;
+  OpAddBlobImage;
+  OpUpdateImage;
+  OpUpdateBlobImage;
+  OpSetBlobImageVisibleArea;
+  OpDeleteImage;
+  OpDeleteBlobImage;
+  OpAddRawFont;
+  OpAddFontDescriptor;
+  OpDeleteFont;
+  OpAddFontInstance;
+  OpDeleteFontInstance;
+  OpAddSharedExternalImage;
+  OpPushExternalImageForTexture;
+  OpUpdateSharedExternalImage;
+};
+
+} // namespace
+} // namespace