Adding upstream version 124.0.1.upstream/124.0.1

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

1 files changed, 1211 insertions, 0 deletions

diff --git a/gfx/layers/apz/src/InputQueue.cpp b/gfx/layers/apz/src/InputQueue.cpp
new file mode 100644
index 0000000000..8ad75a9794
--- /dev/null
+++ b/gfx/layers/apz/src/InputQueue.cpp
@@ -0,0 +1,1211 @@
+/* -*- 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 "InputQueue.h"
+
+#include <inttypes.h>
+
+#include "AsyncPanZoomController.h"
+
+#include "GestureEventListener.h"
+#include "InputBlockState.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/layers/APZInputBridge.h"
+#include "mozilla/layers/APZThreadUtils.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ToString.h"
+#include "OverscrollHandoffState.h"
+#include "QueuedInput.h"
+#include "mozilla/StaticPrefs_apz.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/StaticPrefs_ui.h"
+
+static mozilla::LazyLogModule sApzInpLog("apz.inputqueue");
+#define INPQ_LOG(...) MOZ_LOG(sApzInpLog, LogLevel::Debug, (__VA_ARGS__))
+
+namespace mozilla {
+namespace layers {
+
+InputQueue::InputQueue() = default;
+
+InputQueue::~InputQueue() { mQueuedInputs.Clear(); }
+
+APZEventResult InputQueue::ReceiveInputEvent(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, InputData& aEvent,
+    const Maybe<nsTArray<TouchBehaviorFlags>>& aTouchBehaviors) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  AutoRunImmediateTimeout timeoutRunner{this};
+
+  switch (aEvent.mInputType) {
+    case MULTITOUCH_INPUT: {
+      const MultiTouchInput& event = aEvent.AsMultiTouchInput();
+      return ReceiveTouchInput(aTarget, aFlags, event, aTouchBehaviors);
+    }
+
+    case SCROLLWHEEL_INPUT: {
+      const ScrollWheelInput& event = aEvent.AsScrollWheelInput();
+      return ReceiveScrollWheelInput(aTarget, aFlags, event);
+    }
+
+    case PANGESTURE_INPUT: {
+      const PanGestureInput& event = aEvent.AsPanGestureInput();
+      return ReceivePanGestureInput(aTarget, aFlags, event);
+    }
+
+    case PINCHGESTURE_INPUT: {
+      const PinchGestureInput& event = aEvent.AsPinchGestureInput();
+      return ReceivePinchGestureInput(aTarget, aFlags, event);
+    }
+
+    case MOUSE_INPUT: {
+      MouseInput& event = aEvent.AsMouseInput();
+      return ReceiveMouseInput(aTarget, aFlags, event);
+    }
+
+    case KEYBOARD_INPUT: {
+      // Every keyboard input must have a confirmed target
+      MOZ_ASSERT(aTarget && aFlags.mTargetConfirmed);
+
+      const KeyboardInput& event = aEvent.AsKeyboardInput();
+      return ReceiveKeyboardInput(aTarget, aFlags, event);
+    }
+
+    default: {
+      // The `mStatus` for other input type is only used by tests, so just
+      // pass through the return value of HandleInputEvent() for now.
+      APZEventResult result(aTarget, aFlags);
+      nsEventStatus status =
+          aTarget->HandleInputEvent(aEvent, aTarget->GetTransformToThis());
+      switch (status) {
+        case nsEventStatus_eIgnore:
+          result.SetStatusAsIgnore();
+          break;
+        case nsEventStatus_eConsumeNoDefault:
+          result.SetStatusAsConsumeNoDefault();
+          break;
+        case nsEventStatus_eConsumeDoDefault:
+          result.SetStatusAsConsumeDoDefault(aTarget);
+          break;
+        default:
+          MOZ_ASSERT_UNREACHABLE("An invalid status");
+          break;
+      }
+      return result;
+    }
+  }
+}
+
+APZEventResult InputQueue::ReceiveTouchInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, const MultiTouchInput& aEvent,
+    const Maybe<nsTArray<TouchBehaviorFlags>>& aTouchBehaviors) {
+  APZEventResult result(aTarget, aFlags);
+
+  RefPtr<TouchBlockState> block;
+  bool waitingForContentResponse = false;
+  if (aEvent.mType == MultiTouchInput::MULTITOUCH_START) {
+    nsTArray<TouchBehaviorFlags> currentBehaviors;
+    bool haveBehaviors = false;
+    if (mActiveTouchBlock) {
+      haveBehaviors =
+          mActiveTouchBlock->GetAllowedTouchBehaviors(currentBehaviors);
+      // If the behaviours aren't set, but the main-thread response timer on
+      // the block is expired we still treat it as though it has behaviors,
+      // because in that case we still want to interrupt the fast-fling and
+      // use the default behaviours.
+      haveBehaviors |= mActiveTouchBlock->IsContentResponseTimerExpired();
+    }
+
+    block = StartNewTouchBlock(aTarget, aFlags);
+    INPQ_LOG("started new touch block %p id %" PRIu64 " for target %p\n",
+             block.get(), block->GetBlockId(), aTarget.get());
+
+    // XXX using the chain from |block| here may be wrong in cases where the
+    // target isn't confirmed and the real target turns out to be something
+    // else. For now assume this is rare enough that it's not an issue.
+    if (mQueuedInputs.IsEmpty() && aEvent.mTouches.Length() == 1 &&
+        block->GetOverscrollHandoffChain()->HasFastFlungApzc() &&
+        haveBehaviors) {
+      // If we're already in a fast fling, and a single finger goes down, then
+      // we want special handling for the touch event, because it shouldn't get
+      // delivered to content. Note that we don't set this flag when going
+      // from a fast fling to a pinch state (i.e. second finger goes down while
+      // the first finger is moving).
+      block->SetDuringFastFling();
+      block->SetConfirmedTargetApzc(
+          aTarget, InputBlockState::TargetConfirmationState::eConfirmed,
+          nullptr /* the block was just created so it has no events */,
+          false /* not a scrollbar drag */);
+      block->SetAllowedTouchBehaviors(currentBehaviors);
+      INPQ_LOG("block %p tagged as fast-motion\n", block.get());
+    } else if (aTouchBehaviors) {
+      // If this block isn't started during a fast-fling, and APZCTM has
+      // provided touch behavior information, then put it on the block so
+      // that the ArePointerEventsConsumable call below can use it.
+      block->SetAllowedTouchBehaviors(*aTouchBehaviors);
+    }
+
+    CancelAnimationsForNewBlock(block);
+
+    waitingForContentResponse = MaybeRequestContentResponse(aTarget, block);
+  } else {
+    // for touch inputs that don't start a block, APZCTM shouldn't be giving
+    // us any touch behaviors.
+    MOZ_ASSERT(aTouchBehaviors.isNothing());
+
+    // If the active touch block is for a long tap, add new touch events into
+    // the original touch block, to ensure that they're only processed if the
+    // original touch block is not prevented.
+    block = mActiveTouchBlock && mActiveTouchBlock->ForLongTap()
+                ? mPrevActiveTouchBlock.get()
+                : mActiveTouchBlock.get();
+    if (!block) {
+      NS_WARNING(
+          "Received a non-start touch event while no touch blocks active!");
+      return result;
+    }
+
+    INPQ_LOG("received new touch event (type=%d) in block %p\n", aEvent.mType,
+             block.get());
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  // Note that the |aTarget| the APZCTM sent us may contradict the confirmed
+  // target set on the block. In this case the confirmed target (which may be
+  // null) should take priority. This is equivalent to just always using the
+  // target (confirmed or not) from the block.
+  RefPtr<AsyncPanZoomController> target = block->GetTargetApzc();
+
+  // XXX calling ArePointerEventsConsumable on |target| may be wrong here if
+  // the target isn't confirmed and the real target turns out to be something
+  // else. For now assume this is rare enough that it's not an issue.
+  PointerEventsConsumableFlags consumableFlags;
+  if (target) {
+    consumableFlags = target->ArePointerEventsConsumable(block, aEvent);
+  }
+  if (block->IsDuringFastFling()) {
+    INPQ_LOG("dropping event due to block %p being in fast motion\n",
+             block.get());
+    result.SetStatusForFastFling(*block, aFlags, consumableFlags, target);
+  } else {  // handling depends on ArePointerEventsConsumable()
+    bool consumable = consumableFlags.IsConsumable();
+    const bool wasInSlop = block->IsInSlop();
+    if (block->UpdateSlopState(aEvent, consumable)) {
+      INPQ_LOG("dropping event due to block %p being in %sslop\n", block.get(),
+               consumable ? "" : "mini-");
+      result.SetStatusAsConsumeNoDefault();
+    } else {
+      // If all following conditions are met, we need to wait for a content
+      // response (again);
+      //  1) this is the first event bailing out from in-slop state after a
+      //     long-tap event has been fired
+      //  2) there's any APZ-aware event listeners
+      //  3) the event block hasn't yet been prevented
+      //
+      // An example scenario;
+      //  in the content there are two event listeners for `touchstart` and
+      //  `touchmove` respectively, and doing `preventDefault()` in the
+      //  `touchmove` event listener. Then if the user kept touching at a point
+      //  until a long-tap event happens, then if the user started moving their
+      // finger, we have to wait for a content response twice, one is for
+      // `touchstart` and one is for `touchmove`.
+      if (wasInSlop &&
+          (block->WasLongTapProcessed() || block->IsWaitingLongTapResult()) &&
+          !block->IsTargetOriginallyConfirmed() && !block->ShouldDropEvents()) {
+        INPQ_LOG(
+            "bailing out from in-stop state in block %p after a long-tap "
+            "happened\n",
+            block.get());
+        block->ResetContentResponseTimerExpired();
+        ScheduleMainThreadTimeout(aTarget, block);
+      }
+      block->SetNeedsToWaitTouchMove(false);
+      result.SetStatusForTouchEvent(*block, aFlags, consumableFlags, target);
+    }
+  }
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+  ProcessQueue();
+
+  // If this block just started and is waiting for a content response, but
+  // also in a slop state (i.e. touchstart gets delivered to content but
+  // not any touchmoves), then we might end up in a situation where we don't
+  // get the content response until the timeout is hit because we never exit
+  // the slop state. But if that timeout is longer than the long-press timeout,
+  // then the long-press gets delayed too. Avoid that by scheduling a callback
+  // with the long-press timeout that will force the block to get processed.
+  int32_t longTapTimeout = StaticPrefs::ui_click_hold_context_menus_delay();
+  int32_t contentTimeout = StaticPrefs::apz_content_response_timeout();
+  if (waitingForContentResponse && longTapTimeout < contentTimeout &&
+      block->IsInSlop() && GestureEventListener::IsLongTapEnabled()) {
+    MOZ_ASSERT(aEvent.mType == MultiTouchInput::MULTITOUCH_START);
+    MOZ_ASSERT(!block->IsDuringFastFling());
+    RefPtr<Runnable> maybeLongTap = NewRunnableMethod<uint64_t>(
+        "layers::InputQueue::MaybeLongTapTimeout", this,
+        &InputQueue::MaybeLongTapTimeout, block->GetBlockId());
+    INPQ_LOG("scheduling maybe-long-tap timeout for target %p\n",
+             aTarget.get());
+    aTarget->PostDelayedTask(maybeLongTap.forget(), longTapTimeout);
+  }
+
+  return result;
+}
+
+APZEventResult InputQueue::ReceiveMouseInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, MouseInput& aEvent) {
+  APZEventResult result(aTarget, aFlags);
+
+  // On a new mouse down we can have a new target so we must force a new block
+  // with a new target.
+  bool newBlock = DragTracker::StartsDrag(aEvent);
+
+  RefPtr<DragBlockState> block = newBlock ? nullptr : mActiveDragBlock.get();
+  if (block && block->HasReceivedMouseUp()) {
+    block = nullptr;
+  }
+
+  if (!block && mDragTracker.InDrag()) {
+    // If there's no current drag block, but we're getting a move with a button
+    // down, we need to start a new drag block because we're obviously already
+    // in the middle of a drag (it probably got interrupted by something else).
+    INPQ_LOG(
+        "got a drag event outside a drag block, need to create a block to hold "
+        "it\n");
+    newBlock = true;
+  }
+
+  mDragTracker.Update(aEvent);
+
+  if (!newBlock && !block) {
+    // This input event is not in a drag block, so we're not doing anything
+    // with it, return eIgnore.
+    return result;
+  }
+
+  if (!block) {
+    MOZ_ASSERT(newBlock);
+    block = new DragBlockState(aTarget, aFlags, aEvent);
+
+    INPQ_LOG(
+        "started new drag block %p id %" PRIu64
+        "for %sconfirmed target %p; on scrollbar: %d; on scrollthumb: %d\n",
+        block.get(), block->GetBlockId(), aFlags.mTargetConfirmed ? "" : "un",
+        aTarget.get(), aFlags.mHitScrollbar, aFlags.mHitScrollThumb);
+
+    mActiveDragBlock = block;
+
+    if (aFlags.mHitScrollThumb || !aFlags.mHitScrollbar) {
+      // If we're running autoscroll, we'll always cancel it during the
+      // following call of CancelAnimationsForNewBlock.  At this time,
+      // we don't want to fire `click` event on the web content for web-compat
+      // with Chrome.  Therefore, we notify widget of it with the flag.
+      if ((aEvent.mType == MouseInput::MOUSE_DOWN ||
+           aEvent.mType == MouseInput::MOUSE_UP) &&
+          block->GetOverscrollHandoffChain()->HasAutoscrollApzc()) {
+        aEvent.mPreventClickEvent = true;
+      }
+      CancelAnimationsForNewBlock(block);
+    }
+    MaybeRequestContentResponse(aTarget, block);
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+  ProcessQueue();
+
+  if (DragTracker::EndsDrag(aEvent)) {
+    block->MarkMouseUpReceived();
+  }
+
+  // The event is part of a drag block and could potentially cause
+  // scrolling, so return DoDefault.
+  result.SetStatusAsConsumeDoDefault(*block);
+  return result;
+}
+
+APZEventResult InputQueue::ReceiveScrollWheelInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, const ScrollWheelInput& aEvent) {
+  APZEventResult result(aTarget, aFlags);
+
+  RefPtr<WheelBlockState> block = mActiveWheelBlock.get();
+  // If the block is not accepting new events we'll create a new input block
+  // (and therefore a new wheel transaction).
+  if (block &&
+      (!block->ShouldAcceptNewEvent() || block->MaybeTimeout(aEvent))) {
+    block = nullptr;
+  }
+
+  MOZ_ASSERT(!block || block->InTransaction());
+
+  if (!block) {
+    block = new WheelBlockState(aTarget, aFlags, aEvent);
+    INPQ_LOG("started new scroll wheel block %p id %" PRIu64
+             " for %starget %p\n",
+             block.get(), block->GetBlockId(),
+             aFlags.mTargetConfirmed ? "confirmed " : "", aTarget.get());
+
+    mActiveWheelBlock = block;
+
+    CancelAnimationsForNewBlock(block, ExcludeWheel);
+    MaybeRequestContentResponse(aTarget, block);
+  } else {
+    INPQ_LOG("received new wheel event in block %p\n", block.get());
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  // Note that the |aTarget| the APZCTM sent us may contradict the confirmed
+  // target set on the block. In this case the confirmed target (which may be
+  // null) should take priority. This is equivalent to just always using the
+  // target (confirmed or not) from the block, which is what
+  // ProcessQueue() does.
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+
+  // The WheelBlockState needs to affix a counter to the event before we process
+  // it. Note that the counter is affixed to the copy in the queue rather than
+  // |aEvent|.
+  block->Update(mQueuedInputs.LastElement()->Input()->AsScrollWheelInput());
+
+  ProcessQueue();
+
+  result.SetStatusAsConsumeDoDefault(*block);
+  return result;
+}
+
+APZEventResult InputQueue::ReceiveKeyboardInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, const KeyboardInput& aEvent) {
+  APZEventResult result(aTarget, aFlags);
+
+  RefPtr<KeyboardBlockState> block = mActiveKeyboardBlock.get();
+
+  // If the block is targeting a different Apzc than this keyboard event then
+  // we'll create a new input block
+  if (block && block->GetTargetApzc() != aTarget) {
+    block = nullptr;
+  }
+
+  if (!block) {
+    block = new KeyboardBlockState(aTarget);
+    INPQ_LOG("started new keyboard block %p id %" PRIu64 " for target %p\n",
+             block.get(), block->GetBlockId(), aTarget.get());
+
+    mActiveKeyboardBlock = block;
+  } else {
+    INPQ_LOG("received new keyboard event in block %p\n", block.get());
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+
+  ProcessQueue();
+
+  // If APZ is allowing passive listeners then we must dispatch the event to
+  // content, otherwise we can consume the event.
+  if (StaticPrefs::apz_keyboard_passive_listeners()) {
+    result.SetStatusAsConsumeDoDefault(*block);
+  } else {
+    result.SetStatusAsConsumeNoDefault();
+  }
+  return result;
+}
+
+static bool CanScrollTargetHorizontally(const PanGestureInput& aInitialEvent,
+                                        PanGestureBlockState* aBlock) {
+  PanGestureInput horizontalComponent = aInitialEvent;
+  horizontalComponent.mPanDisplacement.y = 0;
+  ScrollDirections allowedScrollDirections;
+  RefPtr<AsyncPanZoomController> horizontallyScrollableAPZC =
+      aBlock->GetOverscrollHandoffChain()->FindFirstScrollable(
+          horizontalComponent, &allowedScrollDirections,
+          OverscrollHandoffChain::IncludeOverscroll::No);
+  return horizontallyScrollableAPZC &&
+         horizontallyScrollableAPZC == aBlock->GetTargetApzc() &&
+         allowedScrollDirections.contains(ScrollDirection::eHorizontal);
+}
+
+APZEventResult InputQueue::ReceivePanGestureInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, const PanGestureInput& aEvent) {
+  APZEventResult result(aTarget, aFlags);
+
+  if (aEvent.mType == PanGestureInput::PANGESTURE_MAYSTART ||
+      aEvent.mType == PanGestureInput::PANGESTURE_CANCELLED) {
+    // Ignore these events for now.
+    result.SetStatusAsConsumeDoDefault(aTarget);
+    return result;
+  }
+
+  if (aEvent.mType == PanGestureInput::PANGESTURE_INTERRUPTED) {
+    if (RefPtr<PanGestureBlockState> block = mActivePanGestureBlock.get()) {
+      mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+      ProcessQueue();
+    }
+    result.SetStatusAsIgnore();
+    return result;
+  }
+
+  RefPtr<PanGestureBlockState> block;
+  if (aEvent.mType != PanGestureInput::PANGESTURE_START) {
+    block = mActivePanGestureBlock.get();
+  }
+
+  PanGestureInput event = aEvent;
+
+  // Below `SetStatusAsConsumeDoDefault()` preserves `mHandledResult` of
+  // `result` which was set in the ctor of APZEventResult at the top of this
+  // function based on `aFlag` so that the `mHandledResult` value is reliable to
+  // tell whether the event will be handled by the root content APZC at least
+  // for swipe-navigation stuff. E.g. if a pan-start event scrolled the root
+  // scroll container, we don't need to anything for swipe-navigation.
+  result.SetStatusAsConsumeDoDefault();
+
+  if (!block || block->WasInterrupted()) {
+    if (event.mType == PanGestureInput::PANGESTURE_MOMENTUMSTART ||
+        event.mType == PanGestureInput::PANGESTURE_MOMENTUMPAN ||
+        event.mType == PanGestureInput::PANGESTURE_MOMENTUMEND) {
+      // If there are momentum events after an interruption, discard them.
+      // However, if there is a non-momentum event (indicating the user
+      // continued scrolling on the touchpad), a new input block is started
+      // by turning the event into a pan-start below.
+      return result;
+    }
+    if (event.mType != PanGestureInput::PANGESTURE_START) {
+      // Only PANGESTURE_START events are allowed to start a new pan gesture
+      // block, but we really want to start a new block here, so we magically
+      // turn this input into a PANGESTURE_START.
+      INPQ_LOG(
+          "transmogrifying pan input %d to PANGESTURE_START for new block\n",
+          event.mType);
+      event.mType = PanGestureInput::PANGESTURE_START;
+    }
+    block = new PanGestureBlockState(aTarget, aFlags, event);
+    INPQ_LOG("started new pan gesture block %p id %" PRIu64 " for target %p\n",
+             block.get(), block->GetBlockId(), aTarget.get());
+
+    mActivePanGestureBlock = block;
+
+    CancelAnimationsForNewBlock(block);
+    const bool waitingForContentResponse =
+        MaybeRequestContentResponse(aTarget, block);
+
+    if (event.AllowsSwipe() && !CanScrollTargetHorizontally(event, block)) {
+      // We will ask the browser whether this pan event is going to be used for
+      // swipe or not, so we need to wait the response.
+      block->SetNeedsToWaitForBrowserGestureResponse(true);
+      if (!waitingForContentResponse) {
+        ScheduleMainThreadTimeout(aTarget, block);
+      }
+      if (aFlags.mTargetConfirmed) {
+        // This event may trigger a swipe gesture, depending on what our caller
+        // wants to do it. We need to suspend handling of this block until we
+        // get a content response which will tell us whether to proceed or abort
+        // the block.
+        block->SetNeedsToWaitForContentResponse(true);
+
+        // Inform our caller that we haven't scrolled in response to the event
+        // and that a swipe can be started from this event if desired.
+        result.SetStatusAsIgnore();
+      }
+    }
+  } else {
+    INPQ_LOG("received new pan event (type=%d) in block %p\n", aEvent.mType,
+             block.get());
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  // Note that the |aTarget| the APZCTM sent us may contradict the confirmed
+  // target set on the block. In this case the confirmed target (which may be
+  // null) should take priority. This is equivalent to just always using the
+  // target (confirmed or not) from the block, which is what
+  // ProcessQueue() does.
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(event, *block));
+  ProcessQueue();
+
+  return result;
+}
+
+APZEventResult InputQueue::ReceivePinchGestureInput(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags, const PinchGestureInput& aEvent) {
+  APZEventResult result(aTarget, aFlags);
+
+  RefPtr<PinchGestureBlockState> block;
+  if (aEvent.mType != PinchGestureInput::PINCHGESTURE_START) {
+    block = mActivePinchGestureBlock.get();
+  }
+
+  result.SetStatusAsConsumeDoDefault(aTarget);
+
+  if (!block || block->WasInterrupted()) {
+    if (aEvent.mType != PinchGestureInput::PINCHGESTURE_START) {
+      // Only PINCHGESTURE_START events are allowed to start a new pinch gesture
+      // block.
+      INPQ_LOG("pinchgesture block %p was interrupted %d\n", block.get(),
+               block ? block->WasInterrupted() : 0);
+      return result;
+    }
+    block = new PinchGestureBlockState(aTarget, aFlags);
+    INPQ_LOG("started new pinch gesture block %p id %" PRIu64
+             " for target %p\n",
+             block.get(), block->GetBlockId(), aTarget.get());
+
+    mActivePinchGestureBlock = block;
+    block->SetNeedsToWaitForContentResponse(true);
+
+    CancelAnimationsForNewBlock(block);
+    MaybeRequestContentResponse(aTarget, block);
+  } else {
+    INPQ_LOG("received new pinch event (type=%d) in block %p\n", aEvent.mType,
+             block.get());
+  }
+
+  result.mInputBlockId = block->GetBlockId();
+
+  // Note that the |aTarget| the APZCTM sent us may contradict the confirmed
+  // target set on the block. In this case the confirmed target (which may be
+  // null) should take priority. This is equivalent to just always using the
+  // target (confirmed or not) from the block, which is what
+  // ProcessQueue() does.
+  mQueuedInputs.AppendElement(MakeUnique<QueuedInput>(aEvent, *block));
+  ProcessQueue();
+
+  return result;
+}
+
+void InputQueue::CancelAnimationsForNewBlock(InputBlockState* aBlock,
+                                             CancelAnimationFlags aExtraFlags) {
+  // We want to cancel animations here as soon as possible (i.e. without waiting
+  // for content responses) because a finger has gone down and we don't want to
+  // keep moving the content under the finger. However, to prevent "future"
+  // touchstart events from interfering with "past" animations (i.e. from a
+  // previous touch block that is still being processed) we only do this
+  // animation-cancellation if there are no older touch blocks still in the
+  // queue.
+  if (mQueuedInputs.IsEmpty()) {
+    aBlock->GetOverscrollHandoffChain()->CancelAnimations(
+        aExtraFlags | ExcludeOverscroll | ScrollSnap);
+  }
+}
+
+bool InputQueue::MaybeRequestContentResponse(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    CancelableBlockState* aBlock) {
+  bool waitForMainThread = false;
+  if (aBlock->IsTargetConfirmed()) {
+    // Content won't prevent-default this, so we can just set the flag directly.
+    INPQ_LOG("not waiting for content response on block %p\n", aBlock);
+    aBlock->SetContentResponse(false);
+  } else {
+    waitForMainThread = true;
+  }
+  if (aBlock->AsTouchBlock() &&
+      !aBlock->AsTouchBlock()->HasAllowedTouchBehaviors()) {
+    INPQ_LOG("waiting for main thread touch-action info on block %p\n", aBlock);
+    waitForMainThread = true;
+  }
+  if (waitForMainThread) {
+    // We either don't know for sure if aTarget is the right APZC, or we may
+    // need to wait to give content the opportunity to prevent-default the
+    // touch events. Either way we schedule a timeout so the main thread stuff
+    // can run.
+    ScheduleMainThreadTimeout(aTarget, aBlock);
+  }
+  return waitForMainThread;
+}
+
+uint64_t InputQueue::InjectNewTouchBlock(AsyncPanZoomController* aTarget) {
+  AutoRunImmediateTimeout timeoutRunner{this};
+  TouchBlockState* block = StartNewTouchBlockForLongTap(aTarget);
+  INPQ_LOG("injecting new touch block %p with id %" PRIu64 " and target %p\n",
+           block, block->GetBlockId(), aTarget);
+  ScheduleMainThreadTimeout(aTarget, block);
+  return block->GetBlockId();
+}
+
+TouchBlockState* InputQueue::StartNewTouchBlock(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    TargetConfirmationFlags aFlags) {
+  TouchBlockState* newBlock =
+      new TouchBlockState(aTarget, aFlags, mTouchCounter);
+
+  mActiveTouchBlock = newBlock;
+  return newBlock;
+}
+
+TouchBlockState* InputQueue::StartNewTouchBlockForLongTap(
+    const RefPtr<AsyncPanZoomController>& aTarget) {
+  TouchBlockState* newBlock = new TouchBlockState(
+      aTarget, TargetConfirmationFlags{true}, mTouchCounter);
+
+  TouchBlockState* currentBlock = GetCurrentTouchBlock();
+  // We should never enter here without a current touch block, because this
+  // codepath is invoked from the OnLongPress handler in
+  // AsyncPanZoomController, which should bail out if there is no current
+  // touch block.
+  MOZ_ASSERT(currentBlock);
+  newBlock->CopyPropertiesFrom(*currentBlock);
+  newBlock->SetForLongTap();
+
+  // Tell the original touch block that we are going to fire a long tap event.
+  // NOTE: If we get a new touch-move event while we are waiting for a response
+  // of the long-tap event, we need to wait it before processing the original
+  // touch block because if the long-tap event response prevents us from
+  // scrolling we must stop processing any subsequent touch-move events in the
+  // same block.
+  currentBlock->SetWaitingLongTapResult();
+
+  // We need to keep the current block alive, it will be used once after this
+  // new touch block for long-tap was processed.
+  mPrevActiveTouchBlock = currentBlock;
+  mActiveTouchBlock = newBlock;
+  return newBlock;
+}
+
+InputBlockState* InputQueue::GetCurrentBlock() const {
+  APZThreadUtils::AssertOnControllerThread();
+  return mQueuedInputs.IsEmpty() ? nullptr : mQueuedInputs[0]->Block();
+}
+
+TouchBlockState* InputQueue::GetCurrentTouchBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsTouchBlock() : mActiveTouchBlock.get();
+}
+
+WheelBlockState* InputQueue::GetCurrentWheelBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsWheelBlock() : mActiveWheelBlock.get();
+}
+
+DragBlockState* InputQueue::GetCurrentDragBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsDragBlock() : mActiveDragBlock.get();
+}
+
+PanGestureBlockState* InputQueue::GetCurrentPanGestureBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsPanGestureBlock() : mActivePanGestureBlock.get();
+}
+
+PinchGestureBlockState* InputQueue::GetCurrentPinchGestureBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsPinchGestureBlock() : mActivePinchGestureBlock.get();
+}
+
+KeyboardBlockState* InputQueue::GetCurrentKeyboardBlock() const {
+  InputBlockState* block = GetCurrentBlock();
+  return block ? block->AsKeyboardBlock() : mActiveKeyboardBlock.get();
+}
+
+WheelBlockState* InputQueue::GetActiveWheelTransaction() const {
+  WheelBlockState* block = mActiveWheelBlock.get();
+  if (!block || !block->InTransaction()) {
+    return nullptr;
+  }
+  return block;
+}
+
+bool InputQueue::HasReadyTouchBlock() const {
+  return !mQueuedInputs.IsEmpty() &&
+         mQueuedInputs[0]->Block()->AsTouchBlock() &&
+         mQueuedInputs[0]->Block()->AsTouchBlock()->IsReadyForHandling();
+}
+
+bool InputQueue::AllowScrollHandoff() const {
+  if (GetCurrentWheelBlock()) {
+    return GetCurrentWheelBlock()->AllowScrollHandoff();
+  }
+  if (GetCurrentPanGestureBlock()) {
+    return GetCurrentPanGestureBlock()->AllowScrollHandoff();
+  }
+  if (GetCurrentKeyboardBlock()) {
+    return GetCurrentKeyboardBlock()->AllowScrollHandoff();
+  }
+  return true;
+}
+
+bool InputQueue::IsDragOnScrollbar(bool aHitScrollbar) {
+  if (!mDragTracker.InDrag()) {
+    return false;
+  }
+  // Now that we know we are in a drag, get the info from the drag tracker.
+  // We keep it in the tracker rather than the block because the block can get
+  // interrupted by something else (like a wheel event) and then a new block
+  // will get created without the info we want. The tracker will persist though.
+  return mDragTracker.IsOnScrollbar(aHitScrollbar);
+}
+
+void InputQueue::ScheduleMainThreadTimeout(
+    const RefPtr<AsyncPanZoomController>& aTarget,
+    CancelableBlockState* aBlock) {
+  INPQ_LOG("scheduling main thread timeout for target %p\n", aTarget.get());
+  RefPtr<Runnable> timeoutTask = NewRunnableMethod<uint64_t>(
+      "layers::InputQueue::MainThreadTimeout", this,
+      &InputQueue::MainThreadTimeout, aBlock->GetBlockId());
+  int32_t timeout = StaticPrefs::apz_content_response_timeout();
+  if (timeout == 0) {
+    // If the timeout is zero, treat it as a request to ignore any main
+    // thread confirmation and unconditionally use fallback behaviour for
+    // when a timeout is reached. This codepath is used by tests that
+    // want to exercise the fallback behaviour.
+    // To ensure the fallback behaviour is used unconditionally, the timeout
+    // is run right away instead of using PostDelayedTask(). However,
+    // we can't run it right here, because MainThreadTimeout() expects that
+    // the input block has at least one input event in mQueuedInputs, and
+    // the event that triggered this call may not have been added to
+    // mQueuedInputs yet.
+    mImmediateTimeout = std::move(timeoutTask);
+  } else {
+    aTarget->PostDelayedTask(timeoutTask.forget(), timeout);
+  }
+}
+
+InputBlockState* InputQueue::GetBlockForId(uint64_t aInputBlockId) {
+  return FindBlockForId(aInputBlockId, nullptr);
+}
+
+void InputQueue::AddInputBlockCallback(uint64_t aInputBlockId,
+                                       InputBlockCallbackInfo&& aCallbackInfo) {
+  mInputBlockCallbacks.insert(InputBlockCallbackMap::value_type(
+      aInputBlockId, std::move(aCallbackInfo)));
+}
+
+InputBlockState* InputQueue::FindBlockForId(uint64_t aInputBlockId,
+                                            InputData** aOutFirstInput) {
+  for (const auto& queuedInput : mQueuedInputs) {
+    if (queuedInput->Block()->GetBlockId() == aInputBlockId) {
+      if (aOutFirstInput) {
+        *aOutFirstInput = queuedInput->Input();
+      }
+      return queuedInput->Block();
+    }
+  }
+
+  InputBlockState* block = nullptr;
+  if (mActiveTouchBlock && mActiveTouchBlock->GetBlockId() == aInputBlockId) {
+    block = mActiveTouchBlock.get();
+  } else if (mPrevActiveTouchBlock &&
+             mPrevActiveTouchBlock->GetBlockId() == aInputBlockId) {
+    block = mPrevActiveTouchBlock.get();
+  } else if (mActiveWheelBlock &&
+             mActiveWheelBlock->GetBlockId() == aInputBlockId) {
+    block = mActiveWheelBlock.get();
+  } else if (mActiveDragBlock &&
+             mActiveDragBlock->GetBlockId() == aInputBlockId) {
+    block = mActiveDragBlock.get();
+  } else if (mActivePanGestureBlock &&
+             mActivePanGestureBlock->GetBlockId() == aInputBlockId) {
+    block = mActivePanGestureBlock.get();
+  } else if (mActivePinchGestureBlock &&
+             mActivePinchGestureBlock->GetBlockId() == aInputBlockId) {
+    block = mActivePinchGestureBlock.get();
+  } else if (mActiveKeyboardBlock &&
+             mActiveKeyboardBlock->GetBlockId() == aInputBlockId) {
+    block = mActiveKeyboardBlock.get();
+  }
+  // Since we didn't encounter this block while iterating through mQueuedInputs,
+  // it must have no events associated with it at the moment.
+  if (aOutFirstInput) {
+    *aOutFirstInput = nullptr;
+  }
+  return block;
+}
+
+void InputQueue::MainThreadTimeout(uint64_t aInputBlockId) {
+  // It's possible that this function gets called after the controller thread
+  // was discarded during shutdown.
+  if (!APZThreadUtils::IsControllerThreadAlive()) {
+    return;
+  }
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got a main thread timeout; block=%" PRIu64 "\n", aInputBlockId);
+  bool success = false;
+  InputData* firstInput = nullptr;
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, &firstInput);
+  if (inputBlock && inputBlock->AsCancelableBlock()) {
+    CancelableBlockState* block = inputBlock->AsCancelableBlock();
+    // time out the touch-listener response and also confirm the existing
+    // target apzc in the case where the main thread doesn't get back to us
+    // fast enough.
+    success = block->TimeoutContentResponse();
+    success |= block->SetConfirmedTargetApzc(
+        block->GetTargetApzc(),
+        InputBlockState::TargetConfirmationState::eTimedOut, firstInput,
+        // This actually could be a scrollbar drag, but we pass
+        // aForScrollbarDrag=false because for scrollbar drags,
+        // SetConfirmedTargetApzc() will also be called by ConfirmDragBlock(),
+        // and we pass aForScrollbarDrag=true there.
+        false);
+  } else if (inputBlock) {
+    NS_WARNING("input block is not a cancelable block");
+  }
+  if (success) {
+    if (inputBlock->AsTouchBlock() && inputBlock->AsTouchBlock()->IsInSlop()) {
+      // If the touch block is still in slop, it's still possible this block
+      // needs to send a touchmove to content after the long-press gesture
+      // since preventDefault() in a touchmove event handler should stop
+      // handling the block at all.
+      inputBlock->AsTouchBlock()->SetNeedsToWaitTouchMove(true);
+    }
+    ProcessQueue();
+  }
+}
+
+void InputQueue::MaybeLongTapTimeout(uint64_t aInputBlockId) {
+  // It's possible that this function gets called after the controller thread
+  // was discarded during shutdown.
+  if (!APZThreadUtils::IsControllerThreadAlive()) {
+    return;
+  }
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got a maybe-long-tap timeout; block=%" PRIu64 "\n", aInputBlockId);
+
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, nullptr);
+  MOZ_ASSERT(!inputBlock || inputBlock->AsTouchBlock());
+  if (inputBlock && inputBlock->AsTouchBlock()->IsInSlop()) {
+    // If the block is still in slop, it won't have sent a touchmove to content
+    // and so content will not have sent a content response. But also it means
+    // the touchstart should trigger a long-press gesture so let's force the
+    // block to get processed now.
+    MainThreadTimeout(aInputBlockId);
+  }
+}
+
+void InputQueue::ContentReceivedInputBlock(uint64_t aInputBlockId,
+                                           bool aPreventDefault) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got a content response; block=%" PRIu64 " preventDefault=%d\n",
+           aInputBlockId, aPreventDefault);
+  bool success = false;
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, nullptr);
+  if (inputBlock && inputBlock->AsCancelableBlock()) {
+    CancelableBlockState* block = inputBlock->AsCancelableBlock();
+    success = block->SetContentResponse(aPreventDefault);
+  } else if (inputBlock) {
+    NS_WARNING("input block is not a cancelable block");
+  } else {
+    INPQ_LOG("couldn't find block=%" PRIu64 "\n", aInputBlockId);
+  }
+  if (success) {
+    if (ProcessQueue()) {
+      // If we've switched the active touch block back to the original touch
+      // block from the block for long-tap, run ProcessQueue again.
+      // If we haven't yet received new touch-move events which need to be
+      // processed (e.g. we are waiting for a content response for a touch-move
+      // event), below ProcessQueue call is mostly no-op.
+      ProcessQueue();
+    }
+  }
+}
+
+void InputQueue::SetConfirmedTargetApzc(
+    uint64_t aInputBlockId, const RefPtr<AsyncPanZoomController>& aTargetApzc) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got a target apzc; block=%" PRIu64 " guid=%s\n", aInputBlockId,
+           aTargetApzc ? ToString(aTargetApzc->GetGuid()).c_str() : "");
+  bool success = false;
+  InputData* firstInput = nullptr;
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, &firstInput);
+  if (inputBlock && inputBlock->AsCancelableBlock()) {
+    CancelableBlockState* block = inputBlock->AsCancelableBlock();
+    success = block->SetConfirmedTargetApzc(
+        aTargetApzc, InputBlockState::TargetConfirmationState::eConfirmed,
+        firstInput,
+        // This actually could be a scrollbar drag, but we pass
+        // aForScrollbarDrag=false because for scrollbar drags,
+        // SetConfirmedTargetApzc() will also be called by ConfirmDragBlock(),
+        // and we pass aForScrollbarDrag=true there.
+        false);
+  } else if (inputBlock) {
+    NS_WARNING("input block is not a cancelable block");
+  }
+  if (success) {
+    ProcessQueue();
+  }
+}
+
+void InputQueue::ConfirmDragBlock(
+    uint64_t aInputBlockId, const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    const AsyncDragMetrics& aDragMetrics) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got a target apzc; block=%" PRIu64 " guid=%s dragtarget=%" PRIu64
+           "\n",
+           aInputBlockId,
+           aTargetApzc ? ToString(aTargetApzc->GetGuid()).c_str() : "",
+           aDragMetrics.mViewId);
+  bool success = false;
+  InputData* firstInput = nullptr;
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, &firstInput);
+  if (inputBlock && inputBlock->AsDragBlock()) {
+    DragBlockState* block = inputBlock->AsDragBlock();
+
+    // We use the target initial scrollable rect for updating the thumb position
+    // during dragging the thumb even if the scrollable rect got expanded during
+    // the drag.
+    block->SetDragMetrics(aDragMetrics, aTargetApzc->GetScrollableRect());
+    success = block->SetConfirmedTargetApzc(
+        aTargetApzc, InputBlockState::TargetConfirmationState::eConfirmed,
+        firstInput,
+        /* aForScrollbarDrag = */ true);
+  }
+  if (success) {
+    ProcessQueue();
+  }
+}
+
+void InputQueue::SetAllowedTouchBehavior(
+    uint64_t aInputBlockId, const nsTArray<TouchBehaviorFlags>& aBehaviors) {
+  APZThreadUtils::AssertOnControllerThread();
+
+  INPQ_LOG("got allowed touch behaviours; block=%" PRIu64 "\n", aInputBlockId);
+  bool success = false;
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, nullptr);
+  if (inputBlock && inputBlock->AsTouchBlock()) {
+    TouchBlockState* block = inputBlock->AsTouchBlock();
+    success = block->SetAllowedTouchBehaviors(aBehaviors);
+  } else if (inputBlock) {
+    NS_WARNING("input block is not a touch block");
+  }
+  if (success) {
+    ProcessQueue();
+  }
+}
+
+void InputQueue::SetBrowserGestureResponse(uint64_t aInputBlockId,
+                                           BrowserGestureResponse aResponse) {
+  InputBlockState* inputBlock = FindBlockForId(aInputBlockId, nullptr);
+
+  if (inputBlock && inputBlock->AsPanGestureBlock()) {
+    PanGestureBlockState* block = inputBlock->AsPanGestureBlock();
+    block->SetBrowserGestureResponse(aResponse);
+  } else if (inputBlock) {
+    NS_WARNING("input block is not a pan gesture block");
+  }
+  ProcessQueue();
+}
+
+static APZHandledResult GetHandledResultFor(
+    const AsyncPanZoomController* aApzc,
+    const InputBlockState& aCurrentInputBlock, nsEventStatus aEagerStatus) {
+  if (aCurrentInputBlock.ShouldDropEvents()) {
+    return APZHandledResult{APZHandledPlace::HandledByContent, aApzc};
+  }
+
+  if (!aApzc) {
+    return APZHandledResult{APZHandledPlace::HandledByContent, aApzc};
+  }
+
+  if (aApzc->IsRootContent()) {
+    // If the eager status was eIgnore, we would have returned an eager result
+    // of Unhandled if there had been no event handler. Now that we know the
+    // event handler did not preventDefault() the input block, return Unhandled
+    // as the delayed result.
+    // FIXME: A more accurate implementation would be to re-do the entire
+    // computation that determines the status (i.e. calling
+    // ArePointerEventsConsumable()) with the confirmed target APZC.
+    return (aEagerStatus == nsEventStatus_eConsumeDoDefault &&
+            aApzc->CanVerticalScrollWithDynamicToolbar())
+               ? APZHandledResult{APZHandledPlace::HandledByRoot, aApzc}
+               : APZHandledResult{APZHandledPlace::Unhandled, aApzc, true};
+  }
+
+  bool mayTriggerPullToRefresh =
+      aCurrentInputBlock.GetOverscrollHandoffChain()
+          ->ScrollingUpWillTriggerPullToRefresh(aApzc);
+  if (mayTriggerPullToRefresh) {
+    return APZHandledResult{APZHandledPlace::Unhandled, aApzc, true};
+  }
+
+  auto [willMoveDynamicToolbar, rootApzc] =
+      aCurrentInputBlock.GetOverscrollHandoffChain()
+          ->ScrollingDownWillMoveDynamicToolbar(aApzc);
+  if (!willMoveDynamicToolbar) {
+    return APZHandledResult{APZHandledPlace::HandledByContent, aApzc};
+  }
+
+  // Return `HandledByRoot` if scroll positions in all relevant APZC are at the
+  // bottom edge and if there are contents covered by the dynamic toolbar.
+  MOZ_ASSERT(rootApzc && rootApzc->IsRootContent());
+  return APZHandledResult{APZHandledPlace::HandledByRoot, rootApzc};
+}
+
+bool InputQueue::ProcessQueue() {
+  APZThreadUtils::AssertOnControllerThread();
+
+  while (!mQueuedInputs.IsEmpty()) {
+    InputBlockState* curBlock = mQueuedInputs[0]->Block();
+    CancelableBlockState* cancelable = curBlock->AsCancelableBlock();
+    if (cancelable && !cancelable->IsReadyForHandling()) {
+      break;
+    }
+
+    INPQ_LOG(
+        "processing input from block %p; preventDefault %d shouldDropEvents %d "
+        "target %p\n",
+        curBlock, cancelable && cancelable->IsDefaultPrevented(),
+        curBlock->ShouldDropEvents(), curBlock->GetTargetApzc().get());
+    RefPtr<AsyncPanZoomController> target = curBlock->GetTargetApzc();
+
+    // If there is an input block callback registered for this
+    // input block, invoke it.
+    //
+    // NOTE: In the case where the block is a touch block and the block is not
+    // ready to invoke the callback because of waiting a touch move response
+    // from content, we skip the block.
+    if (!curBlock->AsTouchBlock() ||
+        curBlock->AsTouchBlock()->IsReadyForCallback()) {
+      auto it = mInputBlockCallbacks.find(curBlock->GetBlockId());
+      if (it != mInputBlockCallbacks.end()) {
+        INPQ_LOG("invoking the callback for input from block %p id %" PRIu64
+                 "\n",
+                 curBlock, curBlock->GetBlockId());
+        APZHandledResult handledResult =
+            GetHandledResultFor(target, *curBlock, it->second.mEagerStatus);
+        it->second.mCallback(curBlock->GetBlockId(), handledResult);
+        // The callback is one-shot; discard it after calling it.
+        mInputBlockCallbacks.erase(it);
+      }
+    }
+
+    // target may be null here if the initial target was unconfirmed and then
+    // we later got a confirmed null target. in that case drop the events.
+    if (target) {
+      // If the event is targeting a different APZC than the previous one,
+      // we want to clear the previous APZC's gesture state regardless of
+      // whether we're actually dispatching the event or not.
+      if (mLastActiveApzc && mLastActiveApzc != target &&
+          mTouchCounter.GetActiveTouchCount() > 0) {
+        mLastActiveApzc->ResetTouchInputState();
+      }
+      if (curBlock->ShouldDropEvents()) {
+        if (curBlock->AsTouchBlock()) {
+          target->ResetTouchInputState();
+        } else if (curBlock->AsPanGestureBlock()) {
+          target->ResetPanGestureInputState();
+        }
+      } else {
+        UpdateActiveApzc(target);
+        curBlock->DispatchEvent(*(mQueuedInputs[0]->Input()));
+      }
+    }
+    mQueuedInputs.RemoveElementAt(0);
+  }
+
+  bool processQueueAgain = false;
+  if (CanDiscardBlock(mActiveTouchBlock)) {
+    const bool forLongTap = mActiveTouchBlock->ForLongTap();
+    const bool wasDefaultPrevented = mActiveTouchBlock->IsDefaultPrevented();
+    INPQ_LOG("discarding a touch block %p id %" PRIu64 "\n",
+             mActiveTouchBlock.get(), mActiveTouchBlock->GetBlockId());
+    mActiveTouchBlock = nullptr;
+    MOZ_ASSERT_IF(forLongTap, mPrevActiveTouchBlock);
+    if (forLongTap) {
+      INPQ_LOG("switching back to the original touch block %p id %" PRIu64 "\n",
+               mPrevActiveTouchBlock.get(),
+               mPrevActiveTouchBlock->GetBlockId());
+
+      mPrevActiveTouchBlock->SetLongTapProcessed();
+      if (wasDefaultPrevented && !mPrevActiveTouchBlock->IsDefaultPrevented()) {
+        // Take over the preventDefaulted info for the long-tap event (i.e. for
+        // the contextmenu event) to the original touch block so that the
+        // original touch block will never process incoming touch events.
+        mPrevActiveTouchBlock->ResetContentResponseTimerExpired();
+        mPrevActiveTouchBlock->SetContentResponse(true);
+      }
+      mActiveTouchBlock = mPrevActiveTouchBlock;
+      mPrevActiveTouchBlock = nullptr;
+      processQueueAgain = true;
+    }
+  }
+  if (CanDiscardBlock(mActiveWheelBlock)) {
+    mActiveWheelBlock = nullptr;
+  }
+  if (CanDiscardBlock(mActiveDragBlock)) {
+    mActiveDragBlock = nullptr;
+  }
+  if (CanDiscardBlock(mActivePanGestureBlock)) {
+    mActivePanGestureBlock = nullptr;
+  }
+  if (CanDiscardBlock(mActivePinchGestureBlock)) {
+    mActivePinchGestureBlock = nullptr;
+  }
+  if (CanDiscardBlock(mActiveKeyboardBlock)) {
+    mActiveKeyboardBlock = nullptr;
+  }
+
+  return processQueueAgain;
+}
+
+bool InputQueue::CanDiscardBlock(InputBlockState* aBlock) {
+  if (!aBlock ||
+      (aBlock->AsCancelableBlock() &&
+       !aBlock->AsCancelableBlock()->IsReadyForHandling()) ||
+      aBlock->MustStayActive()) {
+    return false;
+  }
+  InputData* firstInput = nullptr;
+  FindBlockForId(aBlock->GetBlockId(), &firstInput);
+  if (firstInput) {
+    // The block has at least one input event still in the queue, so it's
+    // not depleted
+    return false;
+  }
+  return true;
+}
+
+void InputQueue::UpdateActiveApzc(
+    const RefPtr<AsyncPanZoomController>& aNewActive) {
+  mLastActiveApzc = aNewActive;
+}
+
+void InputQueue::Clear() {
+  // On Android, where the controller thread is the Android UI thread,
+  // it's possible for this to be called after the main thread has
+  // already run the shutdown task that clears the state used to
+  // implement APZThreadUtils::AssertOnControllerThread().
+  // In such cases, we still want to perform the cleanup.
+  if (APZThreadUtils::IsControllerThreadAlive()) {
+    APZThreadUtils::AssertOnControllerThread();
+  }
+
+  mQueuedInputs.Clear();
+  mActiveTouchBlock = nullptr;
+  mPrevActiveTouchBlock = nullptr;
+  mActiveWheelBlock = nullptr;
+  mActiveDragBlock = nullptr;
+  mActivePanGestureBlock = nullptr;
+  mActivePinchGestureBlock = nullptr;
+  mActiveKeyboardBlock = nullptr;
+  mLastActiveApzc = nullptr;
+}
+
+InputQueue::AutoRunImmediateTimeout::AutoRunImmediateTimeout(InputQueue* aQueue)
+    : mQueue(aQueue) {
+  MOZ_ASSERT(!mQueue->mImmediateTimeout);
+}
+
+InputQueue::AutoRunImmediateTimeout::~AutoRunImmediateTimeout() {
+  if (mQueue->mImmediateTimeout) {
+    mQueue->mImmediateTimeout->Run();
+    mQueue->mImmediateTimeout = nullptr;
+  }
+}
+
+}  // namespace layers
+}  // namespace mozilla