Adding upstream version 1:115.7.0.upstream/1%115.7.0upstream

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

14 files changed, 4018 insertions, 0 deletions

diff --git a/tools/profiler/gecko/ChildProfilerController.cpp b/tools/profiler/gecko/ChildProfilerController.cpp
new file mode 100644
index 0000000000..f51cb9437d
--- /dev/null
+++ b/tools/profiler/gecko/ChildProfilerController.cpp
@@ -0,0 +1,170 @@
+/* -*- 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 "ChildProfilerController.h"
+
+#include "ProfilerChild.h"
+
+#include "mozilla/ProfilerState.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "nsExceptionHandler.h"
+#include "nsIThread.h"
+#include "nsThreadUtils.h"
+
+using namespace mozilla::ipc;
+
+namespace mozilla {
+
+/* static */
+already_AddRefed<ChildProfilerController> ChildProfilerController::Create(
+    mozilla::ipc::Endpoint<PProfilerChild>&& aEndpoint) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  RefPtr<ChildProfilerController> cpc = new ChildProfilerController();
+  cpc->Init(std::move(aEndpoint));
+  return cpc.forget();
+}
+
+ChildProfilerController::ChildProfilerController()
+    : mThread(nullptr, "ChildProfilerController::mThread") {
+  MOZ_COUNT_CTOR(ChildProfilerController);
+}
+
+void ChildProfilerController::Init(Endpoint<PProfilerChild>&& aEndpoint) {
+  RefPtr<nsIThread> newProfilerChildThread;
+  if (NS_SUCCEEDED(NS_NewNamedThread("ProfilerChild",
+                                     getter_AddRefs(newProfilerChildThread)))) {
+    {
+      auto lock = mThread.Lock();
+      RefPtr<nsIThread>& lockedmThread = lock.ref();
+      MOZ_ASSERT(!lockedmThread, "There is already a ProfilerChild thread");
+      // Copy ref'd ptr into mThread. Don't move/swap, so that
+      // newProfilerChildThread can be used below.
+      lockedmThread = newProfilerChildThread;
+    }
+    // Now that mThread has been set, run SetupProfilerChild on the thread.
+    newProfilerChildThread->Dispatch(
+        NewRunnableMethod<Endpoint<PProfilerChild>&&>(
+            "ChildProfilerController::SetupProfilerChild", this,
+            &ChildProfilerController::SetupProfilerChild, std::move(aEndpoint)),
+        NS_DISPATCH_NORMAL);
+  }
+}
+
+ProfileAndAdditionalInformation
+ChildProfilerController::GrabShutdownProfileAndShutdown() {
+  ProfileAndAdditionalInformation profileAndAdditionalInformation;
+  ShutdownAndMaybeGrabShutdownProfileFirst(&profileAndAdditionalInformation);
+  return profileAndAdditionalInformation;
+}
+
+void ChildProfilerController::Shutdown() {
+  ShutdownAndMaybeGrabShutdownProfileFirst(nullptr);
+}
+
+void ChildProfilerController::ShutdownAndMaybeGrabShutdownProfileFirst(
+    ProfileAndAdditionalInformation* aOutShutdownProfileInformation) {
+  // First, get the owning reference out of mThread, so it cannot be used in
+  // ChildProfilerController after this (including re-entrantly during the
+  // profilerChildThread->Shutdown() inner event loop below).
+  RefPtr<nsIThread> profilerChildThread;
+  {
+    auto lock = mThread.Lock();
+    RefPtr<nsIThread>& lockedmThread = lock.ref();
+    lockedmThread.swap(profilerChildThread);
+  }
+  if (profilerChildThread) {
+    if (profiler_is_active()) {
+      CrashReporter::AnnotateCrashReport(
+          CrashReporter::Annotation::ProfilerChildShutdownPhase,
+          "Profiling - Dispatching ShutdownProfilerChild"_ns);
+      profilerChildThread->Dispatch(
+          NewRunnableMethod<ProfileAndAdditionalInformation*>(
+              "ChildProfilerController::ShutdownProfilerChild", this,
+              &ChildProfilerController::ShutdownProfilerChild,
+              aOutShutdownProfileInformation),
+          NS_DISPATCH_NORMAL);
+      // Shut down the thread. This call will spin until all runnables
+      // (including the ShutdownProfilerChild runnable) have been processed.
+      profilerChildThread->Shutdown();
+    } else {
+      CrashReporter::AnnotateCrashReport(
+          CrashReporter::Annotation::ProfilerChildShutdownPhase,
+          "Not profiling - Running ShutdownProfilerChild"_ns);
+      // If we're not profiling, this operation will be very quick, so it can be
+      // done synchronously. This avoids having to manually shutdown the thread,
+      // which runs a risky inner event loop, see bug 1613798.
+      NS_DispatchAndSpinEventLoopUntilComplete(
+          "ChildProfilerController::ShutdownProfilerChild SYNC"_ns,
+          profilerChildThread,
+          NewRunnableMethod<ProfileAndAdditionalInformation*>(
+              "ChildProfilerController::ShutdownProfilerChild SYNC", this,
+              &ChildProfilerController::ShutdownProfilerChild, nullptr));
+    }
+    // At this point, `profilerChildThread` should be the last reference to the
+    // thread, so it will now get destroyed.
+  }
+}
+
+ChildProfilerController::~ChildProfilerController() {
+  MOZ_COUNT_DTOR(ChildProfilerController);
+
+#ifdef DEBUG
+  {
+    auto lock = mThread.Lock();
+    RefPtr<nsIThread>& lockedmThread = lock.ref();
+    MOZ_ASSERT(
+        !lockedmThread,
+        "Please call Shutdown before destroying ChildProfilerController");
+  }
+#endif
+  MOZ_ASSERT(!mProfilerChild);
+}
+
+void ChildProfilerController::SetupProfilerChild(
+    Endpoint<PProfilerChild>&& aEndpoint) {
+  {
+    auto lock = mThread.Lock();
+    RefPtr<nsIThread>& lockedmThread = lock.ref();
+    // We should be on the ProfilerChild thread. In rare cases, we could already
+    // be in shutdown, in which case mThread is null; we still need to continue,
+    // so that ShutdownProfilerChild can work on a valid mProfilerChild.
+    MOZ_RELEASE_ASSERT(!lockedmThread ||
+                       lockedmThread == NS_GetCurrentThread());
+  }
+  MOZ_ASSERT(aEndpoint.IsValid());
+
+  mProfilerChild = new ProfilerChild();
+  Endpoint<PProfilerChild> endpoint = std::move(aEndpoint);
+
+  if (!endpoint.Bind(mProfilerChild)) {
+    MOZ_CRASH("Failed to bind ProfilerChild!");
+  }
+}
+
+void ChildProfilerController::ShutdownProfilerChild(
+    ProfileAndAdditionalInformation* aOutShutdownProfileInformation) {
+  const bool isProfiling = profiler_is_active();
+  if (aOutShutdownProfileInformation) {
+    CrashReporter::AnnotateCrashReport(
+        CrashReporter::Annotation::ProfilerChildShutdownPhase,
+        isProfiling ? "Profiling - GrabShutdownProfile"_ns
+                    : "Not profiling - GrabShutdownProfile"_ns);
+    *aOutShutdownProfileInformation = mProfilerChild->GrabShutdownProfile();
+  }
+  CrashReporter::AnnotateCrashReport(
+      CrashReporter::Annotation::ProfilerChildShutdownPhase,
+      isProfiling ? "Profiling - Destroying ProfilerChild"_ns
+                  : "Not profiling - Destroying ProfilerChild"_ns);
+  mProfilerChild->Destroy();
+  mProfilerChild = nullptr;
+  CrashReporter::AnnotateCrashReport(
+      CrashReporter::Annotation::ProfilerChildShutdownPhase,
+      isProfiling
+          ? "Profiling - ShutdownProfilerChild complete, waiting for thread shutdown"_ns
+          : "Not Profiling - ShutdownProfilerChild complete, waiting for thread shutdown"_ns);
+}
+
+}  // namespace mozilla
diff --git a/tools/profiler/gecko/PProfiler.ipdl b/tools/profiler/gecko/PProfiler.ipdl
new file mode 100644
index 0000000000..65778b892c
--- /dev/null
+++ b/tools/profiler/gecko/PProfiler.ipdl
@@ -0,0 +1,44 @@
+/* -*- 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 ProfilerTypes;
+
+namespace mozilla {
+
+// PProfiler is a top-level protocol. It is used to let the main process
+// control the Gecko Profiler in other processes, and request profiles from
+// those processes.
+// It is a top-level protocol so that its child endpoint can be on a
+// background thread, so that profiles can be gathered even if the main thread
+// is unresponsive.
+[ChildImpl=virtual, ParentImpl=virtual]
+async protocol PProfiler
+{
+child:
+  // The unused returned value is to have a promise we can await.
+  async Start(ProfilerInitParams params) returns (bool unused);
+  async EnsureStarted(ProfilerInitParams params) returns (bool unused);
+  async Stop() returns (bool unused);
+  async Pause() returns (bool unused);
+  async Resume() returns (bool unused);
+  async PauseSampling() returns (bool unused);
+  async ResumeSampling() returns (bool unused);
+
+  async WaitOnePeriodicSampling() returns (bool sampled);
+
+  async AwaitNextChunkManagerUpdate() returns (ProfileBufferChunkManagerUpdate update);
+  async DestroyReleasedChunksAtOrBefore(TimeStamp timeStamp);
+
+  // The returned shmem may contain an empty string (unavailable), an error
+  // message starting with '*', or a profile as a stringified JSON object.
+  async GatherProfile() returns (IPCProfileAndAdditionalInformation profileAndAdditionalInformation);
+  async GetGatherProfileProgress() returns (GatherProfileProgress progress);
+
+  async ClearAllPages();
+};
+
+} // namespace mozilla
+
diff --git a/tools/profiler/gecko/ProfilerChild.cpp b/tools/profiler/gecko/ProfilerChild.cpp
new file mode 100644
index 0000000000..db7ef99423
--- /dev/null
+++ b/tools/profiler/gecko/ProfilerChild.cpp
@@ -0,0 +1,565 @@
+/* -*- 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 "ProfilerChild.h"
+
+#include "GeckoProfiler.h"
+#include "platform.h"
+#include "ProfilerCodeAddressService.h"
+#include "ProfilerControl.h"
+#include "ProfilerParent.h"
+
+#include "chrome/common/ipc_channel.h"
+#include "nsPrintfCString.h"
+#include "nsThreadUtils.h"
+
+#include <memory>
+
+namespace mozilla {
+
+/* static */ DataMutexBase<ProfilerChild::ProfilerChildAndUpdate,
+                           baseprofiler::detail::BaseProfilerMutex>
+    ProfilerChild::sPendingChunkManagerUpdate{
+        "ProfilerChild::sPendingChunkManagerUpdate"};
+
+ProfilerChild::ProfilerChild()
+    : mThread(NS_GetCurrentThread()), mDestroyed(false) {
+  MOZ_COUNT_CTOR(ProfilerChild);
+}
+
+ProfilerChild::~ProfilerChild() { MOZ_COUNT_DTOR(ProfilerChild); }
+
+void ProfilerChild::ResolveChunkUpdate(
+    PProfilerChild::AwaitNextChunkManagerUpdateResolver& aResolve) {
+  MOZ_ASSERT(!!aResolve,
+             "ResolveChunkUpdate should only be called when there's a pending "
+             "resolver");
+  MOZ_ASSERT(
+      !mChunkManagerUpdate.IsNotUpdate(),
+      "ResolveChunkUpdate should only be called with a real or final update");
+  MOZ_ASSERT(
+      !mDestroyed,
+      "ResolveChunkUpdate should not be called if the actor was destroyed");
+  if (mChunkManagerUpdate.IsFinal()) {
+    // Final update, send a special "unreleased value", but don't clear the
+    // local copy so we know we got the final update.
+    std::move(aResolve)(ProfilerParent::MakeFinalUpdate());
+  } else {
+    // Optimization note: The ProfileBufferChunkManagerUpdate constructor takes
+    // the newly-released chunks nsTArray by reference-to-const, therefore
+    // constructing and then moving the array here would make a copy. So instead
+    // we first give it an empty array, and then we can write the data directly
+    // into the update's array.
+    ProfileBufferChunkManagerUpdate update{
+        mChunkManagerUpdate.UnreleasedBytes(),
+        mChunkManagerUpdate.ReleasedBytes(),
+        mChunkManagerUpdate.OldestDoneTimeStamp(),
+        {}};
+    update.newlyReleasedChunks().SetCapacity(
+        mChunkManagerUpdate.NewlyReleasedChunksRef().size());
+    for (const ProfileBufferControlledChunkManager::ChunkMetadata& chunk :
+         mChunkManagerUpdate.NewlyReleasedChunksRef()) {
+      update.newlyReleasedChunks().EmplaceBack(chunk.mDoneTimeStamp,
+                                               chunk.mBufferBytes);
+    }
+
+    std::move(aResolve)(update);
+
+    // Clear the update we just sent, so it's ready for later updates to be
+    // folded into it.
+    mChunkManagerUpdate.Clear();
+  }
+
+  // Discard the resolver, so it's empty next time there's a new request.
+  aResolve = nullptr;
+}
+
+void ProfilerChild::ProcessChunkManagerUpdate(
+    ProfileBufferControlledChunkManager::Update&& aUpdate) {
+  if (mDestroyed) {
+    return;
+  }
+  // Always store the data, it could be the final update.
+  mChunkManagerUpdate.Fold(std::move(aUpdate));
+  if (mAwaitNextChunkManagerUpdateResolver) {
+    // There is already a pending resolver, give it the info now.
+    ResolveChunkUpdate(mAwaitNextChunkManagerUpdateResolver);
+  }
+}
+
+/* static */ void ProfilerChild::ProcessPendingUpdate() {
+  auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+  if (!lockedUpdate->mProfilerChild || lockedUpdate->mUpdate.IsNotUpdate()) {
+    return;
+  }
+  lockedUpdate->mProfilerChild->mThread->Dispatch(NS_NewRunnableFunction(
+      "ProfilerChild::ProcessPendingUpdate", []() mutable {
+        auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+        if (!lockedUpdate->mProfilerChild ||
+            lockedUpdate->mUpdate.IsNotUpdate()) {
+          return;
+        }
+        lockedUpdate->mProfilerChild->ProcessChunkManagerUpdate(
+            std::move(lockedUpdate->mUpdate));
+        lockedUpdate->mUpdate.Clear();
+      }));
+}
+
+/* static */ bool ProfilerChild::IsLockedOnCurrentThread() {
+  return sPendingChunkManagerUpdate.Mutex().IsLockedOnCurrentThread();
+}
+
+void ProfilerChild::SetupChunkManager() {
+  mChunkManager = profiler_get_controlled_chunk_manager();
+  if (NS_WARN_IF(!mChunkManager)) {
+    return;
+  }
+
+  // Make sure there are no updates (from a previous run).
+  mChunkManagerUpdate.Clear();
+  {
+    auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+    lockedUpdate->mProfilerChild = this;
+    lockedUpdate->mUpdate.Clear();
+  }
+
+  mChunkManager->SetUpdateCallback(
+      [](ProfileBufferControlledChunkManager::Update&& aUpdate) {
+        // Updates from the chunk manager are stored for later processing.
+        // We avoid dispatching a task, as this could deadlock (if the queueing
+        // mutex is held elsewhere).
+        auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+        if (!lockedUpdate->mProfilerChild) {
+          return;
+        }
+        lockedUpdate->mUpdate.Fold(std::move(aUpdate));
+      });
+}
+
+void ProfilerChild::ResetChunkManager() {
+  if (!mChunkManager) {
+    return;
+  }
+
+  // We have a chunk manager, reset the callback, which will add a final
+  // pending update.
+  mChunkManager->SetUpdateCallback({});
+
+  // Clear the pending update.
+  auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+  lockedUpdate->mProfilerChild = nullptr;
+  lockedUpdate->mUpdate.Clear();
+  // And process a final update right now.
+  ProcessChunkManagerUpdate(
+      ProfileBufferControlledChunkManager::Update(nullptr));
+
+  mChunkManager = nullptr;
+  mAwaitNextChunkManagerUpdateResolver = nullptr;
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvStart(
+    const ProfilerInitParams& params, StartResolver&& aResolve) {
+  nsTArray<const char*> filterArray;
+  for (size_t i = 0; i < params.filters().Length(); ++i) {
+    filterArray.AppendElement(params.filters()[i].get());
+  }
+
+  profiler_start(PowerOfTwo32(params.entries()), params.interval(),
+                 params.features(), filterArray.Elements(),
+                 filterArray.Length(), params.activeTabID(), params.duration());
+
+  SetupChunkManager();
+
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvEnsureStarted(
+    const ProfilerInitParams& params, EnsureStartedResolver&& aResolve) {
+  nsTArray<const char*> filterArray;
+  for (size_t i = 0; i < params.filters().Length(); ++i) {
+    filterArray.AppendElement(params.filters()[i].get());
+  }
+
+  profiler_ensure_started(PowerOfTwo32(params.entries()), params.interval(),
+                          params.features(), filterArray.Elements(),
+                          filterArray.Length(), params.activeTabID(),
+                          params.duration());
+
+  SetupChunkManager();
+
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvStop(StopResolver&& aResolve) {
+  ResetChunkManager();
+  profiler_stop();
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvPause(PauseResolver&& aResolve) {
+  profiler_pause();
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvResume(ResumeResolver&& aResolve) {
+  profiler_resume();
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvPauseSampling(
+    PauseSamplingResolver&& aResolve) {
+  profiler_pause_sampling();
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvResumeSampling(
+    ResumeSamplingResolver&& aResolve) {
+  profiler_resume_sampling();
+  aResolve(/* unused */ true);
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvWaitOnePeriodicSampling(
+    WaitOnePeriodicSamplingResolver&& aResolve) {
+  std::shared_ptr<WaitOnePeriodicSamplingResolver> resolve =
+      std::make_shared<WaitOnePeriodicSamplingResolver>(std::move(aResolve));
+  if (!profiler_callback_after_sampling(
+          [self = RefPtr(this), resolve](SamplingState aSamplingState) mutable {
+            if (self->mDestroyed) {
+              return;
+            }
+            MOZ_RELEASE_ASSERT(self->mThread);
+            self->mThread->Dispatch(NS_NewRunnableFunction(
+                "nsProfiler::WaitOnePeriodicSampling result on main thread",
+                [resolve = std::move(resolve), aSamplingState]() {
+                  (*resolve)(aSamplingState ==
+                                 SamplingState::SamplingCompleted ||
+                             aSamplingState ==
+                                 SamplingState::NoStackSamplingCompleted);
+                }));
+          })) {
+    // Callback was not added (e.g., profiler is not running) and will never be
+    // invoked, so we need to resolve the promise here.
+    (*resolve)(false);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvClearAllPages() {
+  profiler_clear_all_pages();
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvAwaitNextChunkManagerUpdate(
+    AwaitNextChunkManagerUpdateResolver&& aResolve) {
+  MOZ_ASSERT(!mDestroyed,
+             "Recv... should not be called if the actor was destroyed");
+  // Pick up pending updates if any.
+  {
+    auto lockedUpdate = sPendingChunkManagerUpdate.Lock();
+    if (lockedUpdate->mProfilerChild && !lockedUpdate->mUpdate.IsNotUpdate()) {
+      mChunkManagerUpdate.Fold(std::move(lockedUpdate->mUpdate));
+      lockedUpdate->mUpdate.Clear();
+    }
+  }
+  if (mChunkManagerUpdate.IsNotUpdate()) {
+    // No data yet, store the resolver for later.
+    mAwaitNextChunkManagerUpdateResolver = std::move(aResolve);
+  } else {
+    // We have data, send it now.
+    ResolveChunkUpdate(aResolve);
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvDestroyReleasedChunksAtOrBefore(
+    const TimeStamp& aTimeStamp) {
+  if (mChunkManager) {
+    mChunkManager->DestroyChunksAtOrBefore(aTimeStamp);
+  }
+  return IPC_OK();
+}
+
+struct GatherProfileThreadParameters
+    : public external::AtomicRefCounted<GatherProfileThreadParameters> {
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(GatherProfileThreadParameters)
+
+  GatherProfileThreadParameters(
+      RefPtr<ProfilerChild> aProfilerChild,
+      RefPtr<ProgressLogger::SharedProgress> aProgress,
+      ProfilerChild::GatherProfileResolver&& aResolver)
+      : profilerChild(std::move(aProfilerChild)),
+        progress(std::move(aProgress)),
+        resolver(std::move(aResolver)) {}
+
+  RefPtr<ProfilerChild> profilerChild;
+
+  FailureLatchSource failureLatchSource;
+
+  // Separate RefPtr used when working on separate thread. This way, if the
+  // "ProfilerChild" thread decides to overwrite its mGatherProfileProgress with
+  // a new one, the work done here will still only use the old one.
+  RefPtr<ProgressLogger::SharedProgress> progress;
+
+  // Resolver for the GatherProfile promise. Must only be called on the
+  // "ProfilerChild" thread.
+  ProfilerChild::GatherProfileResolver resolver;
+};
+
+/* static */
+void ProfilerChild::GatherProfileThreadFunction(
+    void* already_AddRefedParameters) {
+  PR_SetCurrentThreadName("GatherProfileThread");
+
+  RefPtr<GatherProfileThreadParameters> parameters =
+      already_AddRefed<GatherProfileThreadParameters>{
+          static_cast<GatherProfileThreadParameters*>(
+              already_AddRefedParameters)};
+
+  ProgressLogger progressLogger(
+      parameters->progress, "Gather-profile thread started", "Profile sent");
+  using namespace mozilla::literals::ProportionValue_literals;  // For `1_pc`.
+
+  auto writer =
+      MakeUnique<SpliceableChunkedJSONWriter>(parameters->failureLatchSource);
+  if (!profiler_get_profile_json(
+          *writer,
+          /* aSinceTime */ 0,
+          /* aIsShuttingDown */ false,
+          progressLogger.CreateSubLoggerFromTo(
+              1_pc, "profiler_get_profile_json started", 99_pc,
+              "profiler_get_profile_json done"))) {
+    // Failed to get a profile, reset the writer pointer, so that we'll send a
+    // failure message.
+    writer.reset();
+  }
+
+  if (NS_WARN_IF(NS_FAILED(
+          parameters->profilerChild->mThread->Dispatch(NS_NewRunnableFunction(
+              "ProfilerChild::ProcessPendingUpdate",
+              [parameters,
+               // Forward progress logger to on-ProfilerChild-thread task, so
+               // that it doesn't get marked as 100% done when this off-thread
+               // function ends.
+               progressLogger = std::move(progressLogger),
+               writer = std::move(writer)]() mutable {
+                // We are now on the ProfilerChild thread, about to send the
+                // completed profile. Any incoming progress request will now be
+                // handled after this task ends, so updating the progress is now
+                // useless and we can just get rid of the progress storage.
+                if (parameters->profilerChild->mGatherProfileProgress ==
+                    parameters->progress) {
+                  // The ProfilerChild progress is still the one we know.
+                  parameters->profilerChild->mGatherProfileProgress = nullptr;
+                }
+
+                // Shmem allocation and promise resolution must be made on the
+                // ProfilerChild thread, that's why this task was needed here.
+                mozilla::ipc::Shmem shmem;
+                if (writer) {
+                  if (const size_t len = writer->ChunkedWriteFunc().Length();
+                      len < UINT32_MAX) {
+                    bool shmemSuccess = true;
+                    const bool copySuccess =
+                        writer->ChunkedWriteFunc()
+                            .CopyDataIntoLazilyAllocatedBuffer(
+                                [&](size_t allocationSize) -> char* {
+                                  MOZ_ASSERT(allocationSize == len + 1);
+                                  if (parameters->profilerChild->AllocShmem(
+                                          allocationSize, &shmem)) {
+                                    return shmem.get<char>();
+                                  }
+                                  shmemSuccess = false;
+                                  return nullptr;
+                                });
+                    if (!shmemSuccess || !copySuccess) {
+                      const nsPrintfCString message(
+                          (!shmemSuccess)
+                              ? "*Could not create shmem for profile from pid "
+                                "%u (%zu B)"
+                              : "*Could not write profile from pid %u (%zu B)",
+                          unsigned(profiler_current_process_id().ToNumber()),
+                          len);
+                      if (parameters->profilerChild->AllocShmem(
+                              message.Length() + 1, &shmem)) {
+                        strcpy(shmem.get<char>(), message.Data());
+                      }
+                    }
+                  } else {
+                    const nsPrintfCString message(
+                        "*Profile from pid %u bigger (%zu) than shmem max "
+                        "(%zu)",
+                        unsigned(profiler_current_process_id().ToNumber()), len,
+                        size_t(UINT32_MAX));
+                    if (parameters->profilerChild->AllocShmem(
+                            message.Length() + 1, &shmem)) {
+                      strcpy(shmem.get<char>(), message.Data());
+                    }
+                  }
+                  writer = nullptr;
+                } else {
+                  // No profile.
+                  const char* failure =
+                      parameters->failureLatchSource.GetFailure();
+                  const nsPrintfCString message(
+                      "*Could not generate profile from pid %u%s%s",
+                      unsigned(profiler_current_process_id().ToNumber()),
+                      failure ? ", failure: " : "", failure ? failure : "");
+                  if (parameters->profilerChild->AllocShmem(
+                          message.Length() + 1, &shmem)) {
+                    strcpy(shmem.get<char>(), message.Data());
+                  }
+                }
+
+                SharedLibraryInfo sharedLibraryInfo =
+                    SharedLibraryInfo::GetInfoForSelf();
+                parameters->resolver(IPCProfileAndAdditionalInformation{
+                    shmem, Some(ProfileGenerationAdditionalInformation{
+                               std::move(sharedLibraryInfo)})});
+              }))))) {
+    // Failed to dispatch the task to the ProfilerChild thread. The IPC cannot
+    // be resolved on this thread, so it will never be resolved!
+    // And it would be unsafe to modify mGatherProfileProgress; But the parent
+    // should notice that's it's not advancing anymore.
+  }
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvGatherProfile(
+    GatherProfileResolver&& aResolve) {
+  mGatherProfileProgress = MakeRefPtr<ProgressLogger::SharedProgress>();
+  mGatherProfileProgress->SetProgress(ProportionValue{0.0},
+                                      "Received gather-profile request");
+
+  auto parameters = MakeRefPtr<GatherProfileThreadParameters>(
+      this, mGatherProfileProgress, std::move(aResolve));
+
+  // The GatherProfileThreadFunction thread function will cast its void*
+  // argument to already_AddRefed<GatherProfileThreadParameters>.
+  parameters.get()->AddRef();
+  PRThread* gatherProfileThread = PR_CreateThread(
+      PR_SYSTEM_THREAD, GatherProfileThreadFunction, parameters.get(),
+      PR_PRIORITY_NORMAL, PR_GLOBAL_THREAD, PR_UNJOINABLE_THREAD, 0);
+
+  if (!gatherProfileThread) {
+    // Failed to create and start worker thread, resolve with an empty profile.
+    mozilla::ipc::Shmem shmem;
+    if (AllocShmem(1, &shmem)) {
+      shmem.get<char>()[0] = '\0';
+    }
+    parameters->resolver(IPCProfileAndAdditionalInformation{shmem, Nothing()});
+    // And clean up.
+    parameters.get()->Release();
+    mGatherProfileProgress = nullptr;
+  }
+
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ProfilerChild::RecvGetGatherProfileProgress(
+    GetGatherProfileProgressResolver&& aResolve) {
+  if (mGatherProfileProgress) {
+    aResolve(GatherProfileProgress{
+        mGatherProfileProgress->Progress().ToUnderlyingType(),
+        nsCString(mGatherProfileProgress->LastLocation())});
+  } else {
+    aResolve(
+        GatherProfileProgress{ProportionValue::MakeInvalid().ToUnderlyingType(),
+                              nsCString("No gather-profile in progress")});
+  }
+  return IPC_OK();
+}
+
+void ProfilerChild::ActorDestroy(ActorDestroyReason aActorDestroyReason) {
+  mDestroyed = true;
+}
+
+void ProfilerChild::Destroy() {
+  ResetChunkManager();
+  if (!mDestroyed) {
+    Close();
+  }
+}
+
+ProfileAndAdditionalInformation ProfilerChild::GrabShutdownProfile() {
+  LOG("GrabShutdownProfile");
+
+  UniquePtr<ProfilerCodeAddressService> service =
+      profiler_code_address_service_for_presymbolication();
+  FailureLatchSource failureLatch;
+  SpliceableChunkedJSONWriter writer{failureLatch};
+  writer.Start();
+  auto rv = profiler_stream_json_for_this_process(
+      writer, /* aSinceTime */ 0,
+      /* aIsShuttingDown */ true, service.get(), ProgressLogger{});
+  if (rv.isErr()) {
+    const char* failure = writer.GetFailure();
+    return ProfileAndAdditionalInformation(
+        nsPrintfCString("*Profile unavailable for pid %u%s%s",
+                        unsigned(profiler_current_process_id().ToNumber()),
+                        failure ? ", failure: " : "", failure ? failure : ""));
+  }
+
+  auto additionalInfo = rv.unwrap();
+
+  writer.StartArrayProperty("processes");
+  writer.EndArray();
+  writer.End();
+
+  const size_t len = writer.ChunkedWriteFunc().Length();
+  // This string and information are destined to be sent as a shutdown profile,
+  // which is limited by the maximum IPC message size.
+  // TODO: IPC to change to shmem (bug 1780330), raising this limit to
+  // JS::MaxStringLength.
+  if (len + additionalInfo.SizeOf() >=
+      size_t(IPC::Channel::kMaximumMessageSize)) {
+    return ProfileAndAdditionalInformation(
+        nsPrintfCString("*Profile from pid %u bigger (%zu) than IPC max (%zu)",
+                        unsigned(profiler_current_process_id().ToNumber()), len,
+                        size_t(IPC::Channel::kMaximumMessageSize)));
+  }
+
+  nsCString profileCString;
+  if (!profileCString.SetLength(len, fallible)) {
+    return ProfileAndAdditionalInformation(nsPrintfCString(
+        "*Could not allocate %zu bytes for profile from pid %u", len,
+        unsigned(profiler_current_process_id().ToNumber())));
+  }
+  MOZ_ASSERT(*(profileCString.Data() + len) == '\0',
+             "We expected a null at the end of the string buffer, to be "
+             "rewritten by CopyDataIntoLazilyAllocatedBuffer");
+
+  char* const profileBeginWriting = profileCString.BeginWriting();
+  if (!profileBeginWriting) {
+    return ProfileAndAdditionalInformation(
+        nsPrintfCString("*Could not write profile from pid %u",
+                        unsigned(profiler_current_process_id().ToNumber())));
+  }
+
+  // Here, we have enough space reserved in `profileCString`, starting at
+  // `profileBeginWriting`, copy the JSON profile there.
+  if (!writer.ChunkedWriteFunc().CopyDataIntoLazilyAllocatedBuffer(
+          [&](size_t aBufferLen) -> char* {
+            MOZ_RELEASE_ASSERT(aBufferLen == len + 1);
+            return profileBeginWriting;
+          })) {
+    return ProfileAndAdditionalInformation(
+        nsPrintfCString("*Could not copy profile from pid %u",
+                        unsigned(profiler_current_process_id().ToNumber())));
+  }
+  MOZ_ASSERT(*(profileCString.Data() + len) == '\0',
+             "We still expected a null at the end of the string buffer");
+
+  return ProfileAndAdditionalInformation{std::move(profileCString),
+                                         std::move(additionalInfo)};
+}
+
+}  // namespace mozilla
diff --git a/tools/profiler/gecko/ProfilerIOInterposeObserver.cpp b/tools/profiler/gecko/ProfilerIOInterposeObserver.cpp
new file mode 100644
index 0000000000..cf33789f69
--- /dev/null
+++ b/tools/profiler/gecko/ProfilerIOInterposeObserver.cpp
@@ -0,0 +1,216 @@
+/* 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 "ProfilerIOInterposeObserver.h"
+#include "GeckoProfiler.h"
+
+using namespace mozilla;
+
+/* static */
+ProfilerIOInterposeObserver& ProfilerIOInterposeObserver::GetInstance() {
+  static ProfilerIOInterposeObserver sProfilerIOInterposeObserver;
+  return sProfilerIOInterposeObserver;
+}
+
+namespace geckoprofiler::markers {
+struct FileIOMarker {
+  static constexpr Span<const char> MarkerTypeName() {
+    return MakeStringSpan("FileIO");
+  }
+  static void StreamJSONMarkerData(baseprofiler::SpliceableJSONWriter& aWriter,
+                                   const ProfilerString8View& aOperation,
+                                   const ProfilerString8View& aSource,
+                                   const ProfilerString8View& aFilename,
+                                   MarkerThreadId aOperationThreadId) {
+    aWriter.StringProperty("operation", aOperation);
+    aWriter.StringProperty("source", aSource);
+    if (aFilename.Length() != 0) {
+      aWriter.StringProperty("filename", aFilename);
+    }
+    if (!aOperationThreadId.IsUnspecified()) {
+      // Tech note: If `ToNumber()` returns a uint64_t, the conversion to
+      // int64_t is "implementation-defined" before C++20. This is acceptable
+      // here, because this is a one-way conversion to a unique identifier
+      // that's used to visually separate data by thread on the front-end.
+      aWriter.IntProperty(
+          "threadId",
+          static_cast<int64_t>(aOperationThreadId.ThreadId().ToNumber()));
+    }
+  }
+  static MarkerSchema MarkerTypeDisplay() {
+    using MS = MarkerSchema;
+    MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable,
+              MS::Location::TimelineFileIO};
+    schema.AddKeyLabelFormatSearchable("operation", "Operation",
+                                       MS::Format::String,
+                                       MS::Searchable::Searchable);
+    schema.AddKeyLabelFormatSearchable("source", "Source", MS::Format::String,
+                                       MS::Searchable::Searchable);
+    schema.AddKeyLabelFormatSearchable("filename", "Filename",
+                                       MS::Format::FilePath,
+                                       MS::Searchable::Searchable);
+    schema.AddKeyLabelFormatSearchable("threadId", "Thread ID",
+                                       MS::Format::String,
+                                       MS::Searchable::Searchable);
+    return schema;
+  }
+};
+}  // namespace geckoprofiler::markers
+
+static auto GetFilename(IOInterposeObserver::Observation& aObservation) {
+  AUTO_PROFILER_STATS(IO_filename);
+  constexpr size_t scExpectedMaxFilename = 512;
+  nsAutoStringN<scExpectedMaxFilename> filename16;
+  aObservation.Filename(filename16);
+  nsAutoCStringN<scExpectedMaxFilename> filename8;
+  if (!filename16.IsEmpty()) {
+    CopyUTF16toUTF8(filename16, filename8);
+  }
+  return filename8;
+}
+
+void ProfilerIOInterposeObserver::Observe(Observation& aObservation) {
+  if (profiler_is_locked_on_current_thread()) {
+    // Don't observe I/Os originating from the profiler itself (when internally
+    // locked) to avoid deadlocks when calling profiler functions.
+    AUTO_PROFILER_STATS(IO_profiler_locked);
+    return;
+  }
+
+  Maybe<uint32_t> maybeFeatures = profiler_features_if_active_and_unpaused();
+  if (maybeFeatures.isNothing()) {
+    return;
+  }
+  uint32_t features = *maybeFeatures;
+
+  if (!profiler_thread_is_being_profiled_for_markers(
+          profiler_main_thread_id()) &&
+      !profiler_thread_is_being_profiled_for_markers()) {
+    return;
+  }
+
+  AUTO_PROFILER_LABEL("ProfilerIOInterposeObserver", PROFILER);
+  if (IsMainThread()) {
+    // This is the main thread.
+    // Capture a marker if any "IO" feature is on.
+    // If it's not being profiled, we have nowhere to store FileIO markers.
+    if (!profiler_thread_is_being_profiled_for_markers() ||
+        !(features & ProfilerFeature::MainThreadIO)) {
+      return;
+    }
+    AUTO_PROFILER_STATS(IO_MT);
+    nsAutoCString type{aObservation.FileType()};
+    type.AppendLiteral("IO");
+
+    // Store the marker in the current thread.
+    PROFILER_MARKER(
+        type, OTHER,
+        MarkerOptions(
+            MarkerTiming::Interval(aObservation.Start(), aObservation.End()),
+            MarkerStack::Capture()),
+        FileIOMarker,
+        // aOperation
+        ProfilerString8View::WrapNullTerminatedString(
+            aObservation.ObservedOperationString()),
+        // aSource
+        ProfilerString8View::WrapNullTerminatedString(aObservation.Reference()),
+        // aFilename
+        GetFilename(aObservation),
+        // aOperationThreadId - Do not include a thread ID, as it's the same as
+        // the markers. Only include this field when the marker is being sent
+        // from another thread.
+        MarkerThreadId{});
+
+  } else if (profiler_thread_is_being_profiled_for_markers()) {
+    // This is a non-main thread that is being profiled.
+    if (!(features & ProfilerFeature::FileIO)) {
+      return;
+    }
+    AUTO_PROFILER_STATS(IO_off_MT);
+
+    nsAutoCString type{aObservation.FileType()};
+    type.AppendLiteral("IO");
+
+    // Share a backtrace between the marker on this thread, and the marker on
+    // the main thread.
+    UniquePtr<ProfileChunkedBuffer> backtrace = profiler_capture_backtrace();
+
+    // Store the marker in the current thread.
+    PROFILER_MARKER(
+        type, OTHER,
+        MarkerOptions(
+            MarkerTiming::Interval(aObservation.Start(), aObservation.End()),
+            backtrace ? MarkerStack::UseBacktrace(*backtrace)
+                      : MarkerStack::NoStack()),
+        FileIOMarker,
+        // aOperation
+        ProfilerString8View::WrapNullTerminatedString(
+            aObservation.ObservedOperationString()),
+        // aSource
+        ProfilerString8View::WrapNullTerminatedString(aObservation.Reference()),
+        // aFilename
+        GetFilename(aObservation),
+        // aOperationThreadId - Do not include a thread ID, as it's the same as
+        // the markers. Only include this field when the marker is being sent
+        // from another thread.
+        MarkerThreadId{});
+
+    // Store the marker in the main thread as well, with a distinct marker name
+    // and thread id.
+    type.AppendLiteral(" (non-main thread)");
+    PROFILER_MARKER(
+        type, OTHER,
+        MarkerOptions(
+            MarkerTiming::Interval(aObservation.Start(), aObservation.End()),
+            backtrace ? MarkerStack::UseBacktrace(*backtrace)
+                      : MarkerStack::NoStack(),
+            // This is the important piece that changed.
+            // It will send a marker to the main thread.
+            MarkerThreadId::MainThread()),
+        FileIOMarker,
+        // aOperation
+        ProfilerString8View::WrapNullTerminatedString(
+            aObservation.ObservedOperationString()),
+        // aSource
+        ProfilerString8View::WrapNullTerminatedString(aObservation.Reference()),
+        // aFilename
+        GetFilename(aObservation),
+        // aOperationThreadId - Include the thread ID in the payload.
+        MarkerThreadId::CurrentThread());
+
+  } else {
+    // This is a thread that is not being profiled. We still want to capture
+    // file I/Os (to the main thread) if the "FileIOAll" feature is on.
+    if (!(features & ProfilerFeature::FileIOAll)) {
+      return;
+    }
+    AUTO_PROFILER_STATS(IO_other);
+    nsAutoCString type{aObservation.FileType()};
+    if (profiler_is_active_and_thread_is_registered()) {
+      type.AppendLiteral("IO (non-profiled thread)");
+    } else {
+      type.AppendLiteral("IO (unregistered thread)");
+    }
+
+    // Only store this marker on the main thread, as this thread was not being
+    // profiled.
+    PROFILER_MARKER(
+        type, OTHER,
+        MarkerOptions(
+            MarkerTiming::Interval(aObservation.Start(), aObservation.End()),
+            MarkerStack::Capture(),
+            // Store this marker on the main thread.
+            MarkerThreadId::MainThread()),
+        FileIOMarker,
+        // aOperation
+        ProfilerString8View::WrapNullTerminatedString(
+            aObservation.ObservedOperationString()),
+        // aSource
+        ProfilerString8View::WrapNullTerminatedString(aObservation.Reference()),
+        // aFilename
+        GetFilename(aObservation),
+        // aOperationThreadId - Note which thread this marker is coming from.
+        MarkerThreadId::CurrentThread());
+  }
+}
diff --git a/tools/profiler/gecko/ProfilerIOInterposeObserver.h b/tools/profiler/gecko/ProfilerIOInterposeObserver.h
new file mode 100644
index 0000000000..9e22a34f15
--- /dev/null
+++ b/tools/profiler/gecko/ProfilerIOInterposeObserver.h
@@ -0,0 +1,32 @@
+/* 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 PROFILERIOINTERPOSEOBSERVER_H
+#define PROFILERIOINTERPOSEOBSERVER_H
+
+#include "mozilla/IOInterposer.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+/**
+ * This class is the observer that calls into the profiler whenever
+ * main thread I/O occurs.
+ */
+class ProfilerIOInterposeObserver final : public IOInterposeObserver {
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ProfilerIOInterposeObserver)
+
+ public:
+  static ProfilerIOInterposeObserver& GetInstance();
+
+  virtual void Observe(Observation& aObservation) override;
+
+ private:
+  ProfilerIOInterposeObserver() = default;
+  virtual ~ProfilerIOInterposeObserver() {}
+};
+
+}  // namespace mozilla
+
+#endif  // PROFILERIOINTERPOSEOBSERVER_H
diff --git a/tools/profiler/gecko/ProfilerParent.cpp b/tools/profiler/gecko/ProfilerParent.cpp
new file mode 100644
index 0000000000..83bce6d982
--- /dev/null
+++ b/tools/profiler/gecko/ProfilerParent.cpp
@@ -0,0 +1,1002 @@
+/* -*- 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 "ProfilerParent.h"
+
+#ifdef MOZ_GECKO_PROFILER
+#  include "nsProfiler.h"
+#  include "platform.h"
+#endif
+
+#include "GeckoProfiler.h"
+#include "ProfilerControl.h"
+#include "mozilla/BaseAndGeckoProfilerDetail.h"
+#include "mozilla/BaseProfilerDetail.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/DataMutex.h"
+#include "mozilla/IOInterposer.h"
+#include "mozilla/ipc/Endpoint.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/ProfileBufferControlledChunkManager.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/Unused.h"
+#include "nsTArray.h"
+#include "nsThreadUtils.h"
+
+#include <utility>
+
+namespace mozilla {
+
+using namespace ipc;
+
+/* static */
+Endpoint<PProfilerChild> ProfilerParent::CreateForProcess(
+    base::ProcessId aOtherPid) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  Endpoint<PProfilerChild> child;
+#ifdef MOZ_GECKO_PROFILER
+  Endpoint<PProfilerParent> parent;
+  nsresult rv = PProfiler::CreateEndpoints(&parent, &child);
+
+  if (NS_FAILED(rv)) {
+    MOZ_CRASH("Failed to create top level actor for PProfiler!");
+  }
+
+  RefPtr<ProfilerParent> actor = new ProfilerParent(aOtherPid);
+  if (!parent.Bind(actor)) {
+    MOZ_CRASH("Failed to bind parent actor for PProfiler!");
+  }
+
+  actor->Init();
+#endif
+
+  return child;
+}
+
+#ifdef MOZ_GECKO_PROFILER
+
+class ProfilerParentTracker;
+
+// This class is responsible for gathering updates from chunk managers in
+// different process, and request for the oldest chunks to be destroyed whenever
+// the given memory limit is reached.
+class ProfileBufferGlobalController final {
+ public:
+  explicit ProfileBufferGlobalController(size_t aMaximumBytes);
+
+  ~ProfileBufferGlobalController();
+
+  void HandleChildChunkManagerUpdate(
+      base::ProcessId aProcessId,
+      ProfileBufferControlledChunkManager::Update&& aUpdate);
+
+  static bool IsLockedOnCurrentThread();
+
+ private:
+  // Calls aF(Json::Value&).
+  template <typename F>
+  void Log(F&& aF);
+
+  static void LogUpdateChunks(Json::Value& updates, base::ProcessId aProcessId,
+                              const TimeStamp& aTimeStamp, int aChunkDiff);
+  void LogUpdate(base::ProcessId aProcessId,
+                 const ProfileBufferControlledChunkManager::Update& aUpdate);
+  void LogDeletion(base::ProcessId aProcessId, const TimeStamp& aTimeStamp);
+
+  void HandleChunkManagerNonFinalUpdate(
+      base::ProcessId aProcessId,
+      ProfileBufferControlledChunkManager::Update&& aUpdate,
+      ProfileBufferControlledChunkManager& aParentChunkManager);
+
+  const size_t mMaximumBytes;
+
+  const base::ProcessId mParentProcessId = base::GetCurrentProcId();
+
+  struct ParentChunkManagerAndPendingUpdate {
+    ProfileBufferControlledChunkManager* mChunkManager = nullptr;
+    ProfileBufferControlledChunkManager::Update mPendingUpdate;
+  };
+
+  static DataMutexBase<ParentChunkManagerAndPendingUpdate,
+                       baseprofiler::detail::BaseProfilerMutex>
+      sParentChunkManagerAndPendingUpdate;
+
+  size_t mUnreleasedTotalBytes = 0;
+
+  struct PidAndBytes {
+    base::ProcessId mProcessId;
+    size_t mBytes;
+
+    // For searching and sorting.
+    bool operator==(base::ProcessId aSearchedProcessId) const {
+      return mProcessId == aSearchedProcessId;
+    }
+    bool operator==(const PidAndBytes& aOther) const {
+      return mProcessId == aOther.mProcessId;
+    }
+    bool operator<(base::ProcessId aSearchedProcessId) const {
+      return mProcessId < aSearchedProcessId;
+    }
+    bool operator<(const PidAndBytes& aOther) const {
+      return mProcessId < aOther.mProcessId;
+    }
+  };
+  using PidAndBytesArray = nsTArray<PidAndBytes>;
+  PidAndBytesArray mUnreleasedBytesByPid;
+
+  size_t mReleasedTotalBytes = 0;
+
+  struct TimeStampAndBytesAndPid {
+    TimeStamp mTimeStamp;
+    size_t mBytes;
+    base::ProcessId mProcessId;
+
+    // For searching and sorting.
+    bool operator==(const TimeStampAndBytesAndPid& aOther) const {
+      // Sort first by timestamps, and then by pid in rare cases with the same
+      // timestamps.
+      return mTimeStamp == aOther.mTimeStamp && mProcessId == aOther.mProcessId;
+    }
+    bool operator<(const TimeStampAndBytesAndPid& aOther) const {
+      // Sort first by timestamps, and then by pid in rare cases with the same
+      // timestamps.
+      return mTimeStamp < aOther.mTimeStamp ||
+             (MOZ_UNLIKELY(mTimeStamp == aOther.mTimeStamp) &&
+              mProcessId < aOther.mProcessId);
+    }
+  };
+  using TimeStampAndBytesAndPidArray = nsTArray<TimeStampAndBytesAndPid>;
+  TimeStampAndBytesAndPidArray mReleasedChunksByTime;
+};
+
+/* static */
+DataMutexBase<ProfileBufferGlobalController::ParentChunkManagerAndPendingUpdate,
+              baseprofiler::detail::BaseProfilerMutex>
+    ProfileBufferGlobalController::sParentChunkManagerAndPendingUpdate{
+        "ProfileBufferGlobalController::sParentChunkManagerAndPendingUpdate"};
+
+// This singleton class tracks live ProfilerParent's (meaning there's a current
+// connection with a child process).
+// It also knows when the local profiler is running.
+// And when both the profiler is running and at least one child is present, it
+// creates a ProfileBufferGlobalController and forwards chunk updates to it.
+class ProfilerParentTracker final {
+ public:
+  static void StartTracking(ProfilerParent* aParent);
+  static void StopTracking(ProfilerParent* aParent);
+
+  static void ProfilerStarted(uint32_t aEntries);
+  static void ProfilerWillStopIfStarted();
+
+  // Number of non-destroyed tracked ProfilerParents.
+  static size_t ProfilerParentCount();
+
+  template <typename FuncType>
+  static void Enumerate(FuncType&& aIterFunc);
+
+  template <typename FuncType>
+  static void ForChild(base::ProcessId aChildPid, FuncType&& aIterFunc);
+
+  static void ForwardChildChunkManagerUpdate(
+      base::ProcessId aProcessId,
+      ProfileBufferControlledChunkManager::Update&& aUpdate);
+
+  ProfilerParentTracker();
+  ~ProfilerParentTracker();
+
+ private:
+  // Get the singleton instance; Create one on the first request, unless we are
+  // past XPCOMShutdownThreads, which is when it should get destroyed.
+  static ProfilerParentTracker* GetInstance();
+
+  // List of parents for currently-connected child processes.
+  nsTArray<ProfilerParent*> mProfilerParents;
+
+  // If non-0, the parent profiler is running, with this limit (in number of
+  // entries.) This is needed here, because the parent profiler may start
+  // running before child processes are known (e.g., startup profiling).
+  uint32_t mEntries = 0;
+
+  // When the profiler is running and there is at least one parent-child
+  // connection, this is the controller that should receive chunk updates.
+  Maybe<ProfileBufferGlobalController> mMaybeController;
+};
+
+static const Json::StaticString logRoot{"bufferGlobalController"};
+
+template <typename F>
+void ProfileBufferGlobalController::Log(F&& aF) {
+  ProfilingLog::Access([&](Json::Value& aLog) {
+    Json::Value& root = aLog[logRoot];
+    if (!root.isObject()) {
+      root = Json::Value(Json::objectValue);
+      root[Json::StaticString{"logBegin" TIMESTAMP_JSON_SUFFIX}] =
+          ProfilingLog::Timestamp();
+    }
+    std::forward<F>(aF)(root);
+  });
+}
+
+/* static */
+void ProfileBufferGlobalController::LogUpdateChunks(Json::Value& updates,
+                                                    base::ProcessId aProcessId,
+                                                    const TimeStamp& aTimeStamp,
+                                                    int aChunkDiff) {
+  MOZ_ASSERT(updates.isArray());
+  Json::Value row{Json::arrayValue};
+  row.append(Json::Value{Json::UInt64(aProcessId)});
+  row.append(ProfilingLog::Timestamp(aTimeStamp));
+  row.append(Json::Value{Json::Int(aChunkDiff)});
+  updates.append(std::move(row));
+}
+
+void ProfileBufferGlobalController::LogUpdate(
+    base::ProcessId aProcessId,
+    const ProfileBufferControlledChunkManager::Update& aUpdate) {
+  Log([&](Json::Value& aRoot) {
+    Json::Value& updates = aRoot[Json::StaticString{"updates"}];
+    if (!updates.isArray()) {
+      aRoot[Json::StaticString{"updatesSchema"}] =
+          Json::StaticString{"0: pid, 1: chunkRelease_TSms, 3: chunkDiff"};
+      updates = Json::Value{Json::arrayValue};
+    }
+    if (aUpdate.IsFinal()) {
+      LogUpdateChunks(updates, aProcessId, TimeStamp{}, 0);
+    } else if (!aUpdate.IsNotUpdate()) {
+      for (const auto& chunk : aUpdate.NewlyReleasedChunksRef()) {
+        LogUpdateChunks(updates, aProcessId, chunk.mDoneTimeStamp, 1);
+      }
+    }
+  });
+}
+
+void ProfileBufferGlobalController::LogDeletion(base::ProcessId aProcessId,
+                                                const TimeStamp& aTimeStamp) {
+  Log([&](Json::Value& aRoot) {
+    Json::Value& updates = aRoot[Json::StaticString{"updates"}];
+    if (!updates.isArray()) {
+      updates = Json::Value{Json::arrayValue};
+    }
+    LogUpdateChunks(updates, aProcessId, aTimeStamp, -1);
+  });
+}
+
+ProfileBufferGlobalController::ProfileBufferGlobalController(
+    size_t aMaximumBytes)
+    : mMaximumBytes(aMaximumBytes) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  Log([](Json::Value& aRoot) {
+    aRoot[Json::StaticString{"controllerCreationTime" TIMESTAMP_JSON_SUFFIX}] =
+        ProfilingLog::Timestamp();
+  });
+
+  // This is the local chunk manager for this parent process, so updates can be
+  // handled here.
+  ProfileBufferControlledChunkManager* parentChunkManager =
+      profiler_get_controlled_chunk_manager();
+
+  if (NS_WARN_IF(!parentChunkManager)) {
+    Log([](Json::Value& aRoot) {
+      aRoot[Json::StaticString{"controllerCreationFailureReason"}] =
+          "No parent chunk manager";
+    });
+    return;
+  }
+
+  {
+    auto lockedParentChunkManagerAndPendingUpdate =
+        sParentChunkManagerAndPendingUpdate.Lock();
+    lockedParentChunkManagerAndPendingUpdate->mChunkManager =
+        parentChunkManager;
+  }
+
+  parentChunkManager->SetUpdateCallback(
+      [this](ProfileBufferControlledChunkManager::Update&& aUpdate) {
+        MOZ_ASSERT(!aUpdate.IsNotUpdate(),
+                   "Update callback should never be given a non-update");
+        auto lockedParentChunkManagerAndPendingUpdate =
+            sParentChunkManagerAndPendingUpdate.Lock();
+        if (aUpdate.IsFinal()) {
+          // Final update of the parent.
+          // We cannot keep the chunk manager, and there's no point handling
+          // updates anymore. Do some cleanup now, to free resources before
+          // we're destroyed.
+          lockedParentChunkManagerAndPendingUpdate->mChunkManager = nullptr;
+          lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.Clear();
+          mUnreleasedTotalBytes = 0;
+          mUnreleasedBytesByPid.Clear();
+          mReleasedTotalBytes = 0;
+          mReleasedChunksByTime.Clear();
+          return;
+        }
+        if (!lockedParentChunkManagerAndPendingUpdate->mChunkManager) {
+          // No chunk manager, ignore updates.
+          return;
+        }
+        // Special handling of parent non-final updates:
+        // These updates are coming from *this* process, and may originate from
+        // scopes in any thread where any lock is held, so using other locks (to
+        // e.g., dispatch tasks or send IPCs) could trigger a deadlock. Instead,
+        // parent updates are stored locally and handled when the next
+        // non-parent update needs handling, see HandleChildChunkManagerUpdate.
+        lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.Fold(
+            std::move(aUpdate));
+      });
+}
+
+ProfileBufferGlobalController ::~ProfileBufferGlobalController() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  // Extract the parent chunk manager (if still set).
+  // This means any update after this will be ignored.
+  ProfileBufferControlledChunkManager* parentChunkManager = []() {
+    auto lockedParentChunkManagerAndPendingUpdate =
+        sParentChunkManagerAndPendingUpdate.Lock();
+    lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.Clear();
+    return std::exchange(
+        lockedParentChunkManagerAndPendingUpdate->mChunkManager, nullptr);
+  }();
+  if (parentChunkManager) {
+    // We had not received a final update yet, so the chunk manager is still
+    // valid. Reset the callback in the chunk manager, this will immediately
+    // invoke the callback with the final empty update; see handling above.
+    parentChunkManager->SetUpdateCallback({});
+  }
+}
+
+void ProfileBufferGlobalController::HandleChildChunkManagerUpdate(
+    base::ProcessId aProcessId,
+    ProfileBufferControlledChunkManager::Update&& aUpdate) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  MOZ_ASSERT(aProcessId != mParentProcessId);
+
+  MOZ_ASSERT(!aUpdate.IsNotUpdate(),
+             "HandleChildChunkManagerUpdate should not be given a non-update");
+
+  auto lockedParentChunkManagerAndPendingUpdate =
+      sParentChunkManagerAndPendingUpdate.Lock();
+  if (!lockedParentChunkManagerAndPendingUpdate->mChunkManager) {
+    // No chunk manager, ignore updates.
+    return;
+  }
+
+  if (aUpdate.IsFinal()) {
+    // Final update in a child process, remove all traces of that process.
+    LogUpdate(aProcessId, aUpdate);
+    size_t index = mUnreleasedBytesByPid.BinaryIndexOf(aProcessId);
+    if (index != PidAndBytesArray::NoIndex) {
+      // We already have a value for this pid.
+      PidAndBytes& pidAndBytes = mUnreleasedBytesByPid[index];
+      mUnreleasedTotalBytes -= pidAndBytes.mBytes;
+      mUnreleasedBytesByPid.RemoveElementAt(index);
+    }
+
+    size_t released = 0;
+    mReleasedChunksByTime.RemoveElementsBy(
+        [&released, aProcessId](const auto& chunk) {
+          const bool match = chunk.mProcessId == aProcessId;
+          if (match) {
+            released += chunk.mBytes;
+          }
+          return match;
+        });
+    if (released != 0) {
+      mReleasedTotalBytes -= released;
+    }
+
+    // Total can only have gone down, so there's no need to check the limit.
+    return;
+  }
+
+  // Non-final update in child process.
+
+  // Before handling the child update, we may have pending updates from the
+  // parent, which can be processed now since we're in an IPC callback outside
+  // of any profiler-related scope.
+  if (!lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.IsNotUpdate()) {
+    MOZ_ASSERT(
+        !lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.IsFinal());
+    HandleChunkManagerNonFinalUpdate(
+        mParentProcessId,
+        std::move(lockedParentChunkManagerAndPendingUpdate->mPendingUpdate),
+        *lockedParentChunkManagerAndPendingUpdate->mChunkManager);
+    lockedParentChunkManagerAndPendingUpdate->mPendingUpdate.Clear();
+  }
+
+  HandleChunkManagerNonFinalUpdate(
+      aProcessId, std::move(aUpdate),
+      *lockedParentChunkManagerAndPendingUpdate->mChunkManager);
+}
+
+/* static */
+bool ProfileBufferGlobalController::IsLockedOnCurrentThread() {
+  return sParentChunkManagerAndPendingUpdate.Mutex().IsLockedOnCurrentThread();
+}
+
+void ProfileBufferGlobalController::HandleChunkManagerNonFinalUpdate(
+    base::ProcessId aProcessId,
+    ProfileBufferControlledChunkManager::Update&& aUpdate,
+    ProfileBufferControlledChunkManager& aParentChunkManager) {
+  MOZ_ASSERT(!aUpdate.IsFinal());
+  LogUpdate(aProcessId, aUpdate);
+
+  size_t index = mUnreleasedBytesByPid.BinaryIndexOf(aProcessId);
+  if (index != PidAndBytesArray::NoIndex) {
+    // We already have a value for this pid.
+    PidAndBytes& pidAndBytes = mUnreleasedBytesByPid[index];
+    mUnreleasedTotalBytes =
+        mUnreleasedTotalBytes - pidAndBytes.mBytes + aUpdate.UnreleasedBytes();
+    pidAndBytes.mBytes = aUpdate.UnreleasedBytes();
+  } else {
+    // New pid.
+    mUnreleasedBytesByPid.InsertElementSorted(
+        PidAndBytes{aProcessId, aUpdate.UnreleasedBytes()});
+    mUnreleasedTotalBytes += aUpdate.UnreleasedBytes();
+  }
+
+  size_t destroyedReleased = 0;
+  if (!aUpdate.OldestDoneTimeStamp().IsNull()) {
+    size_t i = 0;
+    for (; i < mReleasedChunksByTime.Length(); ++i) {
+      if (mReleasedChunksByTime[i].mTimeStamp >=
+          aUpdate.OldestDoneTimeStamp()) {
+        break;
+      }
+    }
+    // Here, i is the index of the first item that's at or after
+    // aUpdate.mOldestDoneTimeStamp, so chunks from aProcessId before that have
+    // been destroyed.
+    while (i != 0) {
+      --i;
+      const TimeStampAndBytesAndPid& item = mReleasedChunksByTime[i];
+      if (item.mProcessId == aProcessId) {
+        destroyedReleased += item.mBytes;
+        mReleasedChunksByTime.RemoveElementAt(i);
+      }
+    }
+  }
+
+  size_t newlyReleased = 0;
+  for (const ProfileBufferControlledChunkManager::ChunkMetadata& chunk :
+       aUpdate.NewlyReleasedChunksRef()) {
+    newlyReleased += chunk.mBufferBytes;
+    mReleasedChunksByTime.InsertElementSorted(TimeStampAndBytesAndPid{
+        chunk.mDoneTimeStamp, chunk.mBufferBytes, aProcessId});
+  }
+
+  mReleasedTotalBytes = mReleasedTotalBytes - destroyedReleased + newlyReleased;
+
+#  ifdef DEBUG
+  size_t totalReleased = 0;
+  for (const TimeStampAndBytesAndPid& item : mReleasedChunksByTime) {
+    totalReleased += item.mBytes;
+  }
+  MOZ_ASSERT(mReleasedTotalBytes == totalReleased);
+#  endif  // DEBUG
+
+  std::vector<ProfileBufferControlledChunkManager::ChunkMetadata> toDestroy;
+  while (mUnreleasedTotalBytes + mReleasedTotalBytes > mMaximumBytes &&
+         !mReleasedChunksByTime.IsEmpty()) {
+    // We have reached the global memory limit, and there *are* released chunks
+    // that can be destroyed. Start with the first one, which is the oldest.
+    const TimeStampAndBytesAndPid& oldest = mReleasedChunksByTime[0];
+    LogDeletion(oldest.mProcessId, oldest.mTimeStamp);
+    mReleasedTotalBytes -= oldest.mBytes;
+    if (oldest.mProcessId == mParentProcessId) {
+      aParentChunkManager.DestroyChunksAtOrBefore(oldest.mTimeStamp);
+    } else {
+      ProfilerParentTracker::ForChild(
+          oldest.mProcessId,
+          [timestamp = oldest.mTimeStamp](ProfilerParent* profilerParent) {
+            Unused << profilerParent->SendDestroyReleasedChunksAtOrBefore(
+                timestamp);
+          });
+    }
+    mReleasedChunksByTime.RemoveElementAt(0);
+  }
+}
+
+/* static */
+ProfilerParentTracker* ProfilerParentTracker::GetInstance() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  // The main instance pointer, it will be initialized at most once, before
+  // XPCOMShutdownThreads.
+  static UniquePtr<ProfilerParentTracker> instance = nullptr;
+  if (MOZ_UNLIKELY(!instance)) {
+    if (PastShutdownPhase(ShutdownPhase::XPCOMShutdownThreads)) {
+      return nullptr;
+    }
+
+    instance = MakeUnique<ProfilerParentTracker>();
+
+    // The tracker should get destroyed before threads are shutdown, because its
+    // destruction closes extant channels, which could trigger promise
+    // rejections that need to be dispatched to other threads.
+    ClearOnShutdown(&instance, ShutdownPhase::XPCOMShutdownThreads);
+  }
+
+  return instance.get();
+}
+
+/* static */
+void ProfilerParentTracker::StartTracking(ProfilerParent* aProfilerParent) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  if (tracker->mMaybeController.isNothing() && tracker->mEntries != 0) {
+    // There is no controller yet, but the profiler has started.
+    // Since we're adding a ProfilerParent, it's a good time to start
+    // controlling the global memory usage of the profiler.
+    // (And this helps delay the Controller startup, because the parent profiler
+    // can start *very* early in the process, when some resources like threads
+    // are not ready yet.)
+    tracker->mMaybeController.emplace(size_t(tracker->mEntries) * 8u);
+  }
+
+  tracker->mProfilerParents.AppendElement(aProfilerParent);
+}
+
+/* static */
+void ProfilerParentTracker::StopTracking(ProfilerParent* aParent) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  tracker->mProfilerParents.RemoveElement(aParent);
+}
+
+/* static */
+void ProfilerParentTracker::ProfilerStarted(uint32_t aEntries) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  tracker->mEntries = aEntries;
+
+  if (tracker->mMaybeController.isNothing() &&
+      !tracker->mProfilerParents.IsEmpty()) {
+    // We are already tracking child processes, so it's a good time to start
+    // controlling the global memory usage of the profiler.
+    tracker->mMaybeController.emplace(size_t(tracker->mEntries) * 8u);
+  }
+}
+
+/* static */
+void ProfilerParentTracker::ProfilerWillStopIfStarted() {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  tracker->mEntries = 0;
+  tracker->mMaybeController = Nothing{};
+}
+
+/* static */
+size_t ProfilerParentTracker::ProfilerParentCount() {
+  size_t count = 0;
+  ProfilerParentTracker* tracker = GetInstance();
+  if (tracker) {
+    for (ProfilerParent* profilerParent : tracker->mProfilerParents) {
+      if (!profilerParent->mDestroyed) {
+        ++count;
+      }
+    }
+  }
+  return count;
+}
+
+template <typename FuncType>
+/* static */
+void ProfilerParentTracker::Enumerate(FuncType&& aIterFunc) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  for (ProfilerParent* profilerParent : tracker->mProfilerParents) {
+    if (!profilerParent->mDestroyed) {
+      aIterFunc(profilerParent);
+    }
+  }
+}
+
+template <typename FuncType>
+/* static */
+void ProfilerParentTracker::ForChild(base::ProcessId aChildPid,
+                                     FuncType&& aIterFunc) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker) {
+    return;
+  }
+
+  for (ProfilerParent* profilerParent : tracker->mProfilerParents) {
+    if (profilerParent->mChildPid == aChildPid) {
+      if (!profilerParent->mDestroyed) {
+        std::forward<FuncType>(aIterFunc)(profilerParent);
+      }
+      return;
+    }
+  }
+}
+
+/* static */
+void ProfilerParentTracker::ForwardChildChunkManagerUpdate(
+    base::ProcessId aProcessId,
+    ProfileBufferControlledChunkManager::Update&& aUpdate) {
+  ProfilerParentTracker* tracker = GetInstance();
+  if (!tracker || tracker->mMaybeController.isNothing()) {
+    return;
+  }
+
+  MOZ_ASSERT(!aUpdate.IsNotUpdate(),
+             "No process should ever send a non-update");
+  tracker->mMaybeController->HandleChildChunkManagerUpdate(aProcessId,
+                                                           std::move(aUpdate));
+}
+
+ProfilerParentTracker::ProfilerParentTracker() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  MOZ_COUNT_CTOR(ProfilerParentTracker);
+}
+
+ProfilerParentTracker::~ProfilerParentTracker() {
+  // This destructor should only be called on the main thread.
+  MOZ_RELEASE_ASSERT(NS_IsMainThread() ||
+                     // OR we're not on the main thread (including if we are
+                     // past the end of `main()`), which is fine *if* there are
+                     // no ProfilerParent's still registered, in which case
+                     // nothing else will happen in this destructor anyway.
+                     // See bug 1713971 for more information.
+                     mProfilerParents.IsEmpty());
+  MOZ_COUNT_DTOR(ProfilerParentTracker);
+
+  // Close the channels of any profiler parents that haven't been destroyed.
+  for (ProfilerParent* profilerParent : mProfilerParents.Clone()) {
+    if (!profilerParent->mDestroyed) {
+      // Keep the object alive until the call to Close() has completed.
+      // Close() will trigger a call to DeallocPProfilerParent.
+      RefPtr<ProfilerParent> actor = profilerParent;
+      actor->Close();
+    }
+  }
+}
+
+ProfilerParent::ProfilerParent(base::ProcessId aChildPid)
+    : mChildPid(aChildPid), mDestroyed(false) {
+  MOZ_COUNT_CTOR(ProfilerParent);
+
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+}
+
+void ProfilerParent::Init() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  ProfilerParentTracker::StartTracking(this);
+
+  // We propagated the profiler state from the parent process to the child
+  // process through MOZ_PROFILER_STARTUP* environment variables.
+  // However, the profiler state might have changed in this process since then,
+  // and now that an active communication channel has been established with the
+  // child process, it's a good time to sync up the two profilers again.
+
+  int entries = 0;
+  Maybe<double> duration = Nothing();
+  double interval = 0;
+  mozilla::Vector<const char*> filters;
+  uint32_t features;
+  uint64_t activeTabID;
+  profiler_get_start_params(&entries, &duration, &interval, &features, &filters,
+                            &activeTabID);
+
+  if (entries != 0) {
+    ProfilerInitParams ipcParams;
+    ipcParams.enabled() = true;
+    ipcParams.entries() = entries;
+    ipcParams.duration() = duration;
+    ipcParams.interval() = interval;
+    ipcParams.features() = features;
+    ipcParams.activeTabID() = activeTabID;
+
+    // If the filters exclude our pid, make sure it's stopped, otherwise
+    // continue with starting it.
+    if (!profiler::detail::FiltersExcludePid(
+            filters, ProfilerProcessId::FromNumber(mChildPid))) {
+      ipcParams.filters().SetCapacity(filters.length());
+      for (const char* filter : filters) {
+        ipcParams.filters().AppendElement(filter);
+      }
+
+      Unused << SendEnsureStarted(ipcParams);
+      RequestChunkManagerUpdate();
+      return;
+    }
+  }
+
+  Unused << SendStop();
+}
+#endif  // MOZ_GECKO_PROFILER
+
+ProfilerParent::~ProfilerParent() {
+  MOZ_COUNT_DTOR(ProfilerParent);
+
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+#ifdef MOZ_GECKO_PROFILER
+  ProfilerParentTracker::StopTracking(this);
+#endif
+}
+
+#ifdef MOZ_GECKO_PROFILER
+/* static */
+nsTArray<ProfilerParent::SingleProcessProfilePromiseAndChildPid>
+ProfilerParent::GatherProfiles() {
+  nsTArray<SingleProcessProfilePromiseAndChildPid> results;
+  if (!NS_IsMainThread()) {
+    return results;
+  }
+
+  results.SetCapacity(ProfilerParentTracker::ProfilerParentCount());
+  ProfilerParentTracker::Enumerate([&](ProfilerParent* profilerParent) {
+    results.AppendElement(SingleProcessProfilePromiseAndChildPid{
+        profilerParent->SendGatherProfile(), profilerParent->mChildPid});
+  });
+  return results;
+}
+
+/* static */
+RefPtr<ProfilerParent::SingleProcessProgressPromise>
+ProfilerParent::RequestGatherProfileProgress(base::ProcessId aChildPid) {
+  RefPtr<SingleProcessProgressPromise> promise;
+  ProfilerParentTracker::ForChild(
+      aChildPid, [&promise](ProfilerParent* profilerParent) {
+        promise = profilerParent->SendGetGatherProfileProgress();
+      });
+  return promise;
+}
+
+// Magic value for ProfileBufferChunkManagerUpdate::unreleasedBytes meaning
+// that this is a final update from a child.
+constexpr static uint64_t scUpdateUnreleasedBytesFINAL = uint64_t(-1);
+
+/* static */
+ProfileBufferChunkManagerUpdate ProfilerParent::MakeFinalUpdate() {
+  return ProfileBufferChunkManagerUpdate{
+      uint64_t(scUpdateUnreleasedBytesFINAL), 0, TimeStamp{},
+      nsTArray<ProfileBufferChunkMetadata>{}};
+}
+
+/* static */
+bool ProfilerParent::IsLockedOnCurrentThread() {
+  return ProfileBufferGlobalController::IsLockedOnCurrentThread();
+}
+
+void ProfilerParent::RequestChunkManagerUpdate() {
+  if (mDestroyed) {
+    return;
+  }
+
+  RefPtr<AwaitNextChunkManagerUpdatePromise> updatePromise =
+      SendAwaitNextChunkManagerUpdate();
+  updatePromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [self = RefPtr<ProfilerParent>(this)](
+          const ProfileBufferChunkManagerUpdate& aUpdate) {
+        if (aUpdate.unreleasedBytes() == scUpdateUnreleasedBytesFINAL) {
+          // Special value meaning it's the final update from that child.
+          ProfilerParentTracker::ForwardChildChunkManagerUpdate(
+              self->mChildPid,
+              ProfileBufferControlledChunkManager::Update(nullptr));
+        } else {
+          // Not the final update, translate it.
+          std::vector<ProfileBufferControlledChunkManager::ChunkMetadata>
+              chunks;
+          if (!aUpdate.newlyReleasedChunks().IsEmpty()) {
+            chunks.reserve(aUpdate.newlyReleasedChunks().Length());
+            for (const ProfileBufferChunkMetadata& chunk :
+                 aUpdate.newlyReleasedChunks()) {
+              chunks.emplace_back(chunk.doneTimeStamp(), chunk.bufferBytes());
+            }
+          }
+          // Let the tracker handle it.
+          ProfilerParentTracker::ForwardChildChunkManagerUpdate(
+              self->mChildPid,
+              ProfileBufferControlledChunkManager::Update(
+                  aUpdate.unreleasedBytes(), aUpdate.releasedBytes(),
+                  aUpdate.oldestDoneTimeStamp(), std::move(chunks)));
+          // This was not a final update, so start a new request.
+          self->RequestChunkManagerUpdate();
+        }
+      },
+      [self = RefPtr<ProfilerParent>(this)](
+          mozilla::ipc::ResponseRejectReason aReason) {
+        // Rejection could be for a number of reasons, assume the child will
+        // not respond anymore, so we pretend we received a final update.
+        ProfilerParentTracker::ForwardChildChunkManagerUpdate(
+            self->mChildPid,
+            ProfileBufferControlledChunkManager::Update(nullptr));
+      });
+}
+
+// Ref-counted class that resolves a promise on destruction.
+// Usage:
+// RefPtr<GenericPromise> f() {
+//   return PromiseResolverOnDestruction::RunTask(
+//     [](RefPtr<PromiseResolverOnDestruction> aPromiseResolver){
+//       // Give *copies* of aPromiseResolver to asynchronous sub-tasks, the
+//       // last remaining RefPtr destruction will resolve the promise.
+//     });
+// }
+class PromiseResolverOnDestruction {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(PromiseResolverOnDestruction)
+
+  template <typename TaskFunction>
+  static RefPtr<GenericPromise> RunTask(TaskFunction&& aTaskFunction) {
+    RefPtr<PromiseResolverOnDestruction> promiseResolver =
+        new PromiseResolverOnDestruction();
+    RefPtr<GenericPromise> promise =
+        promiseResolver->mPromiseHolder.Ensure(__func__);
+    std::forward<TaskFunction>(aTaskFunction)(std::move(promiseResolver));
+    return promise;
+  }
+
+ private:
+  PromiseResolverOnDestruction() = default;
+
+  ~PromiseResolverOnDestruction() {
+    mPromiseHolder.ResolveIfExists(/* unused */ true, __func__);
+  }
+
+  MozPromiseHolder<GenericPromise> mPromiseHolder;
+};
+
+// Given a ProfilerParentSendFunction: (ProfilerParent*) -> some MozPromise,
+// run the function on all live ProfilerParents and return a GenericPromise, and
+// when their promise gets resolve, resolve our Generic promise.
+template <typename ProfilerParentSendFunction>
+static RefPtr<GenericPromise> SendAndConvertPromise(
+    ProfilerParentSendFunction&& aProfilerParentSendFunction) {
+  if (!NS_IsMainThread()) {
+    return GenericPromise::CreateAndResolve(/* unused */ true, __func__);
+  }
+
+  return PromiseResolverOnDestruction::RunTask(
+      [&](RefPtr<PromiseResolverOnDestruction> aPromiseResolver) {
+        ProfilerParentTracker::Enumerate([&](ProfilerParent* profilerParent) {
+          std::forward<ProfilerParentSendFunction>(aProfilerParentSendFunction)(
+              profilerParent)
+              ->Then(GetMainThreadSerialEventTarget(), __func__,
+                     [aPromiseResolver](
+                         typename std::remove_reference_t<
+                             decltype(*std::forward<ProfilerParentSendFunction>(
+                                 aProfilerParentSendFunction)(
+                                 profilerParent))>::ResolveOrRejectValue&&) {
+                       // Whatever the resolution/rejection is, do nothing.
+                       // The lambda aPromiseResolver ref-count will decrease.
+                     });
+        });
+      });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerStarted(
+    nsIProfilerStartParams* aParams) {
+  if (!NS_IsMainThread()) {
+    return GenericPromise::CreateAndResolve(/* unused */ true, __func__);
+  }
+
+  ProfilerInitParams ipcParams;
+  double duration;
+  ipcParams.enabled() = true;
+  aParams->GetEntries(&ipcParams.entries());
+  aParams->GetDuration(&duration);
+  if (duration > 0.0) {
+    ipcParams.duration() = Some(duration);
+  } else {
+    ipcParams.duration() = Nothing();
+  }
+  aParams->GetInterval(&ipcParams.interval());
+  aParams->GetFeatures(&ipcParams.features());
+  ipcParams.filters() = aParams->GetFilters().Clone();
+  // We need filters as a Span<const char*> to test pids in the lambda below.
+  auto filtersCStrings = nsTArray<const char*>{aParams->GetFilters().Length()};
+  for (const auto& filter : aParams->GetFilters()) {
+    filtersCStrings.AppendElement(filter.Data());
+  }
+  aParams->GetActiveTabID(&ipcParams.activeTabID());
+
+  ProfilerParentTracker::ProfilerStarted(ipcParams.entries());
+
+  return SendAndConvertPromise([&](ProfilerParent* profilerParent) {
+    if (profiler::detail::FiltersExcludePid(
+            filtersCStrings,
+            ProfilerProcessId::FromNumber(profilerParent->mChildPid))) {
+      // This pid is excluded, don't start the profiler at all.
+      return PProfilerParent::StartPromise::CreateAndResolve(/* unused */ true,
+                                                             __func__);
+    }
+    auto promise = profilerParent->SendStart(ipcParams);
+    profilerParent->RequestChunkManagerUpdate();
+    return promise;
+  });
+}
+
+/* static */
+void ProfilerParent::ProfilerWillStopIfStarted() {
+  if (!NS_IsMainThread()) {
+    return;
+  }
+
+  ProfilerParentTracker::ProfilerWillStopIfStarted();
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerStopped() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendStop();
+  });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerPaused() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendPause();
+  });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerResumed() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendResume();
+  });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerPausedSampling() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendPauseSampling();
+  });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::ProfilerResumedSampling() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendResumeSampling();
+  });
+}
+
+/* static */
+void ProfilerParent::ClearAllPages() {
+  if (!NS_IsMainThread()) {
+    return;
+  }
+
+  ProfilerParentTracker::Enumerate([](ProfilerParent* profilerParent) {
+    Unused << profilerParent->SendClearAllPages();
+  });
+}
+
+/* static */
+RefPtr<GenericPromise> ProfilerParent::WaitOnePeriodicSampling() {
+  return SendAndConvertPromise([](ProfilerParent* profilerParent) {
+    return profilerParent->SendWaitOnePeriodicSampling();
+  });
+}
+
+void ProfilerParent::ActorDestroy(ActorDestroyReason aActorDestroyReason) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  mDestroyed = true;
+}
+
+#endif
+
+}  // namespace mozilla
diff --git a/tools/profiler/gecko/ProfilerTypes.ipdlh b/tools/profiler/gecko/ProfilerTypes.ipdlh
new file mode 100644
index 0000000000..6255d47db0
--- /dev/null
+++ b/tools/profiler/gecko/ProfilerTypes.ipdlh
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 8 -*- */
+/* 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 class mozilla::TimeStamp from "mozilla/TimeStamp.h";
+using struct mozilla::ProfileGenerationAdditionalInformation from "ProfileAdditionalInformation.h";
+
+namespace mozilla {
+
+struct ProfilerInitParams {
+  bool enabled;
+  uint32_t entries;
+  double? duration;
+  double interval;
+  uint32_t features;
+  uint64_t activeTabID;
+  nsCString[] filters;
+};
+
+struct ProfileBufferChunkMetadata {
+  TimeStamp doneTimeStamp;
+  uint32_t bufferBytes;
+};
+
+struct ProfileBufferChunkManagerUpdate {
+  uint64_t unreleasedBytes;
+  uint64_t releasedBytes;
+  TimeStamp oldestDoneTimeStamp;
+  ProfileBufferChunkMetadata[] newlyReleasedChunks;
+};
+
+struct GatherProfileProgress {
+  uint32_t progressProportionValueUnderlyingType;
+  nsCString progressLocation;
+};
+
+struct IPCProfileAndAdditionalInformation {
+  Shmem profileShmem;
+  ProfileGenerationAdditionalInformation? additionalInformation;
+};
+
+} // namespace mozilla
diff --git a/tools/profiler/gecko/components.conf b/tools/profiler/gecko/components.conf
new file mode 100644
index 0000000000..b1775c37ab
--- /dev/null
+++ b/tools/profiler/gecko/components.conf
@@ -0,0 +1,17 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# 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/.
+
+Classes = [
+    {
+        'js_name': 'profiler',
+        'cid': '{25db9b8e-8123-4de1-b66d-8bbbedf2cdf4}',
+        'contract_ids': ['@mozilla.org/tools/profiler;1'],
+        'interfaces': ['nsIProfiler'],
+        'type': 'nsProfiler',
+        'headers': ['/tools/profiler/gecko/nsProfiler.h'],
+        'init_method': 'Init',
+    },
+]
diff --git a/tools/profiler/gecko/nsIProfiler.idl b/tools/profiler/gecko/nsIProfiler.idl
new file mode 100644
index 0000000000..8b501d4b9f
--- /dev/null
+++ b/tools/profiler/gecko/nsIProfiler.idl
@@ -0,0 +1,208 @@
+/* -*- Mode: IDL; tab-width: 2; 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 "nsISupports.idl"
+
+%{C++
+#include "mozilla/Maybe.h"
+#include "nsTArrayForwardDeclare.h"
+#include "nsStringFwd.h"
+#include "mozilla/MozPromise.h"
+%}
+
+[ref] native nsCString(const nsCString);
+[ref] native StringArrayRef(const nsTArray<nsCString>);
+native ProfileDataBufferMozPromise(RefPtr<mozilla::MozPromise<FallibleTArray<uint8_t>, nsresult, true>>);
+
+/**
+ * Start-up parameters for subprocesses are passed through nsIObserverService,
+ * which, unfortunately, means we need to implement nsISupports in order to
+ * go through it.
+ */
+[scriptable, builtinclass, uuid(0a175ba7-8fcf-4ce9-9c4b-ccc6272f4425)]
+interface nsIProfilerStartParams : nsISupports
+{
+  readonly attribute uint32_t entries;
+  readonly attribute double duration;
+  readonly attribute double interval;
+  readonly attribute uint32_t features;
+  readonly attribute uint64_t activeTabID;
+
+  [noscript, notxpcom, nostdcall] StringArrayRef getFilters();
+};
+
+[scriptable, builtinclass, uuid(ead3f75c-0e0e-4fbb-901c-1e5392ef5b2a)]
+interface nsIProfiler : nsISupports
+{
+  /*
+   * Control functions return as soon as this process' profiler has done its
+   * work. The returned promise gets resolved when sub-processes have completed
+   * their operation, or immediately if there are no sub-processes.
+   */
+  [implicit_jscontext]
+  Promise StartProfiler(in uint32_t aEntries, in double aInterval,
+                        in Array<AUTF8String> aFeatures,
+                        [optional] in Array<AUTF8String> aFilters,
+                        [optional] in uint64_t aActiveTabID,
+                        [optional] in double aDuration);
+  [implicit_jscontext]
+  Promise StopProfiler();
+  boolean IsPaused();
+  [implicit_jscontext]
+  Promise Pause();
+  [implicit_jscontext]
+  Promise Resume();
+  boolean IsSamplingPaused();
+  [implicit_jscontext]
+  Promise PauseSampling();
+  [implicit_jscontext]
+  Promise ResumeSampling();
+
+  /*
+   * Resolves the returned promise after at least one full periodic sampling in
+   * each process.
+   * Rejects the promise if sampler is not running (yet, or anymore, or paused)
+   * in the parent process.
+   * This is mainly useful in tests, to wait just long enough to guarantee that
+   * at least one sample was taken in each process.
+   */
+  [implicit_jscontext]
+  Promise waitOnePeriodicSampling();
+
+  /*
+   * Returns the JSON string of the profile. If aSinceTime is passed, only
+   * report samples taken at >= aSinceTime.
+   */
+  string GetProfile([optional] in double aSinceTime);
+
+  /*
+   * Returns a JS object of the profile. If aSinceTime is passed, only report
+   * samples taken at >= aSinceTime.
+   */
+  [implicit_jscontext]
+  jsval getProfileData([optional] in double aSinceTime);
+
+  [implicit_jscontext]
+  Promise getProfileDataAsync([optional] in double aSinceTime);
+
+  [implicit_jscontext]
+  Promise getProfileDataAsArrayBuffer([optional] in double aSinceTime);
+
+  [implicit_jscontext]
+  Promise getProfileDataAsGzippedArrayBuffer([optional] in double aSinceTime);
+
+  /**
+   * Asynchronously dump the profile collected so far to a file.
+   * Returns a promise that resolves once the file has been written, with data
+   * from all responsive Firefox processes. Note: This blocks the parent process
+   * while collecting its own data, then unblocks while child processes data is
+   * being collected.
+   * `aFilename` may be a full path, or a path relative to where Firefox was
+   * launched. The target directory must already exist.
+   */
+  [implicit_jscontext]
+  Promise dumpProfileToFileAsync(in ACString aFilename,
+                                 [optional] in double aSinceTime);
+
+  /**
+   * Synchronously dump the profile collected so far in this process to a file.
+   * This profile will only contain data from the parent process, and from child
+   * processes that have ended during the session; other currently-live
+   * processes are ignored.
+   * `aFilename` may be a full path, or a path relative to where Firefox was
+   * launched. The target directory must already exist.
+   */
+  void dumpProfileToFile(in string aFilename);
+
+  boolean IsActive();
+
+  /**
+   * Clear all registered and unregistered page information in prifiler.
+   */
+  void ClearAllPages();
+
+  /**
+   * Returns an array of the features that are supported in this build.
+   * Features may vary depending on platform and build flags.
+   */
+  Array<AUTF8String> GetFeatures();
+
+  /**
+   * Returns a JavaScript object that contains a description of the currently configured
+   * state of the profiler when the profiler is active. This can be useful to assert
+   * the UI of the profiler's recording panel in tests. It returns null when the profiler
+   * is not active.
+   */
+  [implicit_jscontext]
+  readonly attribute jsval activeConfiguration;
+
+  /**
+   * Returns an array of all features that are supported by the profiler.
+   * The array may contain features that are not supported in this build.
+   */
+  Array<AUTF8String> GetAllFeatures();
+
+  void GetBufferInfo(out uint32_t aCurrentPosition, out uint32_t aTotalSize,
+                     out uint32_t aGeneration);
+
+  /**
+   * Returns the elapsed time, in milliseconds, since the profiler's epoch.
+   * The epoch is guaranteed to be constant for the duration of the
+   * process, but is otherwise arbitrary.
+   */
+  double getElapsedTime();
+
+  /**
+   * Contains an array of shared library objects.
+   * Every object has the properties:
+   *  - start:      The start address of the memory region occupied by this library.
+   *  - end:        The end address of the memory region occupied by this library.
+   *  - offset:     Usually zero, except on Linux / Android if the first mapped
+   *                section of the library has been mapped to an address that's
+   *                different from the library's base address.
+   *                Then offset = start - baseAddress.
+   *  - name:       The name (file basename) of the binary.
+   *  - path:       The full absolute path to the binary.
+   *  - debugName:  On Windows, the name of the pdb file for the binary. On other
+   *                platforms, the same as |name|.
+   *  - debugPath:  On Windows, the full absolute path of the pdb file for the
+   *                binary. On other platforms, the same as |path|.
+   *  - arch:       On Mac, the name of the architecture that identifies the right
+   *                binary image of a fat binary. Example values are "i386", "x86_64",
+   *                and "x86_64h". (x86_64h is used for binaries that contain
+   *                instructions that are specific to the Intel Haswell microarchitecture.)
+   *                On non-Mac platforms, arch is "".
+   *  - breakpadId: A unique identifier string for this library, as used by breakpad.
+   */
+  [implicit_jscontext]
+  readonly attribute jsval sharedLibraries;
+
+  /**
+   * Returns a promise that resolves to a SymbolTableAsTuple for the binary at
+   * the given path.
+   *
+   * SymbolTable as tuple: [addrs, index, buffer]
+   * Contains a symbol table, which can be used to map addresses to strings.
+   *
+   * The first element of this tuple, commonly named "addrs", is a sorted array of
+   * symbol addresses, as library-relative offsets in bytes, in ascending order.
+   * The third element of this tuple, commonly named "buffer", is a buffer of
+   * bytes that contains all strings from this symbol table, in the order of the
+   * addresses they correspond to, in utf-8 encoded form, all concatenated
+   * together.
+   * The second element of this tuple, commonly named "index", contains positions
+   * into "buffer". For every address, that position is where the string for that
+   * address starts in the buffer.
+   * index.length == addrs.length + 1.
+   * index[addrs.length] is the end position of the last string in the buffer.
+   *
+   * The string for the address addrs[i] is
+   * (new TextDecoder()).decode(buffer.subarray(index[i], index[i + 1]))
+   */
+  [implicit_jscontext]
+  Promise getSymbolTable(in ACString aDebugPath, in ACString aBreakpadID);
+
+  [notxpcom, nostdcall] ProfileDataBufferMozPromise getProfileDataAsGzippedArrayBufferAndroid(in double aSinceTime);
+};
diff --git a/tools/profiler/gecko/nsProfiler.cpp b/tools/profiler/gecko/nsProfiler.cpp
new file mode 100644
index 0000000000..66e32ce2bc
--- /dev/null
+++ b/tools/profiler/gecko/nsProfiler.cpp
@@ -0,0 +1,1487 @@
+/* -*- Mode: C++; tab-width: 20; 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 "nsProfiler.h"
+
+#include <fstream>
+#include <limits>
+#include <sstream>
+#include <string>
+#include <utility>
+
+#include "GeckoProfiler.h"
+#include "ProfilerControl.h"
+#include "ProfilerParent.h"
+#include "js/Array.h"  // JS::NewArrayObject
+#include "js/JSON.h"
+#include "js/PropertyAndElement.h"  // JS_SetElement
+#include "js/Value.h"
+#include "json/json.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/JSONStringWriteFuncs.h"
+#include "mozilla/SchedulerGroup.h"
+#include "mozilla/Services.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/Preferences.h"
+#include "nsComponentManagerUtils.h"
+#include "nsIInterfaceRequestor.h"
+#include "nsIInterfaceRequestorUtils.h"
+#include "nsILoadContext.h"
+#include "nsIWebNavigation.h"
+#include "nsProfilerStartParams.h"
+#include "nsProxyRelease.h"
+#include "nsString.h"
+#include "nsThreadUtils.h"
+#include "platform.h"
+#include "shared-libraries.h"
+#include "zlib.h"
+
+#ifndef ANDROID
+#  include <cstdio>
+#else
+#  include <android/log.h>
+#endif
+
+using namespace mozilla;
+
+using dom::AutoJSAPI;
+using dom::Promise;
+using std::string;
+
+static constexpr size_t scLengthMax = size_t(JS::MaxStringLength);
+// Used when trying to add more JSON data, to account for the extra space needed
+// for the log and to close the profile.
+static constexpr size_t scLengthAccumulationThreshold = scLengthMax - 16 * 1024;
+
+NS_IMPL_ISUPPORTS(nsProfiler, nsIProfiler)
+
+nsProfiler::nsProfiler() : mGathering(false) {}
+
+nsProfiler::~nsProfiler() {
+  if (mSymbolTableThread) {
+    mSymbolTableThread->Shutdown();
+  }
+  ResetGathering(NS_ERROR_ILLEGAL_DURING_SHUTDOWN);
+}
+
+nsresult nsProfiler::Init() { return NS_OK; }
+
+template <typename JsonLogObjectUpdater>
+void nsProfiler::Log(JsonLogObjectUpdater&& aJsonLogObjectUpdater) {
+  if (mGatheringLog) {
+    MOZ_ASSERT(mGatheringLog->isObject());
+    std::forward<JsonLogObjectUpdater>(aJsonLogObjectUpdater)(*mGatheringLog);
+    MOZ_ASSERT(mGatheringLog->isObject());
+  }
+}
+
+template <typename JsonArrayAppender>
+void nsProfiler::LogEvent(JsonArrayAppender&& aJsonArrayAppender) {
+  Log([&](Json::Value& aRoot) {
+    Json::Value& events = aRoot[Json::StaticString{"events"}];
+    if (!events.isArray()) {
+      events = Json::Value{Json::arrayValue};
+    }
+    Json::Value newEvent{Json::arrayValue};
+    newEvent.append(ProfilingLog::Timestamp());
+    std::forward<JsonArrayAppender>(aJsonArrayAppender)(newEvent);
+    MOZ_ASSERT(newEvent.isArray());
+    events.append(std::move(newEvent));
+  });
+}
+
+void nsProfiler::LogEventLiteralString(const char* aEventString) {
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{aEventString});
+  });
+}
+
+static nsresult FillVectorFromStringArray(Vector<const char*>& aVector,
+                                          const nsTArray<nsCString>& aArray) {
+  if (NS_WARN_IF(!aVector.reserve(aArray.Length()))) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+  for (auto& entry : aArray) {
+    aVector.infallibleAppend(entry.get());
+  }
+  return NS_OK;
+}
+
+// Given a PromiseReturningFunction: () -> GenericPromise,
+// run the function, and return a JS Promise (through aPromise) that will be
+// resolved when the function's GenericPromise gets resolved.
+template <typename PromiseReturningFunction>
+static nsresult RunFunctionAndConvertPromise(
+    JSContext* aCx, Promise** aPromise,
+    PromiseReturningFunction&& aPromiseReturningFunction) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  std::forward<PromiseReturningFunction>(aPromiseReturningFunction)()->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [promise](GenericPromise::ResolveOrRejectValue&&) {
+        promise->MaybeResolveWithUndefined();
+      });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::StartProfiler(uint32_t aEntries, double aInterval,
+                          const nsTArray<nsCString>& aFeatures,
+                          const nsTArray<nsCString>& aFilters,
+                          uint64_t aActiveTabID, double aDuration,
+                          JSContext* aCx, Promise** aPromise) {
+  ResetGathering(NS_ERROR_DOM_ABORT_ERR);
+
+  Vector<const char*> featureStringVector;
+  nsresult rv = FillVectorFromStringArray(featureStringVector, aFeatures);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+  uint32_t features = ParseFeaturesFromStringArray(
+      featureStringVector.begin(), featureStringVector.length());
+  Maybe<double> duration = aDuration > 0.0 ? Some(aDuration) : Nothing();
+
+  Vector<const char*> filterStringVector;
+  rv = FillVectorFromStringArray(filterStringVector, aFilters);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return RunFunctionAndConvertPromise(aCx, aPromise, [&]() {
+    return profiler_start(PowerOfTwo32(aEntries), aInterval, features,
+                          filterStringVector.begin(),
+                          filterStringVector.length(), aActiveTabID, duration);
+  });
+}
+
+NS_IMETHODIMP
+nsProfiler::StopProfiler(JSContext* aCx, Promise** aPromise) {
+  ResetGathering(NS_ERROR_DOM_ABORT_ERR);
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_stop(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::IsPaused(bool* aIsPaused) {
+  *aIsPaused = profiler_is_paused();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::Pause(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_pause(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::Resume(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(aCx, aPromise,
+                                      []() { return profiler_resume(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::IsSamplingPaused(bool* aIsSamplingPaused) {
+  *aIsSamplingPaused = profiler_is_sampling_paused();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::PauseSampling(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(
+      aCx, aPromise, []() { return profiler_pause_sampling(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::ResumeSampling(JSContext* aCx, Promise** aPromise) {
+  return RunFunctionAndConvertPromise(
+      aCx, aPromise, []() { return profiler_resume_sampling(); });
+}
+
+NS_IMETHODIMP
+nsProfiler::ClearAllPages() {
+  profiler_clear_all_pages();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::WaitOnePeriodicSampling(JSContext* aCx, Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  // The callback cannot officially own the promise RefPtr directly, because
+  // `Promise` doesn't support multi-threading, and the callback could destroy
+  // the promise in the sampler thread.
+  // `nsMainThreadPtrHandle` ensures that the promise can only be destroyed on
+  // the main thread. And the invocation from the Sampler thread immediately
+  // dispatches a task back to the main thread, to resolve/reject the promise.
+  // The lambda needs to be `mutable`, to allow moving-from
+  // `promiseHandleInSampler`.
+  if (!profiler_callback_after_sampling(
+          [promiseHandleInSampler = nsMainThreadPtrHandle<Promise>(
+               new nsMainThreadPtrHolder<Promise>(
+                   "WaitOnePeriodicSampling promise for Sampler", promise))](
+              SamplingState aSamplingState) mutable {
+            SchedulerGroup::Dispatch(
+                TaskCategory::Other,
+                NS_NewRunnableFunction(
+                    "nsProfiler::WaitOnePeriodicSampling result on main thread",
+                    [promiseHandleInMT = std::move(promiseHandleInSampler),
+                     aSamplingState]() mutable {
+                      switch (aSamplingState) {
+                        case SamplingState::JustStopped:
+                        case SamplingState::SamplingPaused:
+                          promiseHandleInMT->MaybeReject(NS_ERROR_FAILURE);
+                          break;
+
+                        case SamplingState::NoStackSamplingCompleted:
+                        case SamplingState::SamplingCompleted:
+                          // The parent process has succesfully done a sampling,
+                          // check the child processes (if any).
+                          ProfilerParent::WaitOnePeriodicSampling()->Then(
+                              GetMainThreadSerialEventTarget(), __func__,
+                              [promiseHandleInMT =
+                                   std::move(promiseHandleInMT)](
+                                  GenericPromise::ResolveOrRejectValue&&) {
+                                promiseHandleInMT->MaybeResolveWithUndefined();
+                              });
+                          break;
+
+                        default:
+                          MOZ_ASSERT(false, "Unexpected SamplingState value");
+                          promiseHandleInMT->MaybeReject(
+                              NS_ERROR_DOM_UNKNOWN_ERR);
+                          break;
+                      }
+                    }));
+          })) {
+    // Callback was not added (e.g., profiler is not running) and will never be
+    // invoked, so we need to resolve the promise here.
+    promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+  }
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfile(double aSinceTime, char** aProfile) {
+  mozilla::UniquePtr<char[]> profile = profiler_get_profile(aSinceTime);
+  *aProfile = profile.release();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetSharedLibraries(JSContext* aCx,
+                               JS::MutableHandle<JS::Value> aResult) {
+  JS::Rooted<JS::Value> val(aCx);
+  {
+    JSONStringWriteFunc<nsCString> buffer;
+    JSONWriter w(buffer, JSONWriter::SingleLineStyle);
+    w.StartArrayElement();
+    SharedLibraryInfo sharedLibraryInfo = SharedLibraryInfo::GetInfoForSelf();
+    sharedLibraryInfo.SortByAddress();
+    AppendSharedLibraries(w, sharedLibraryInfo);
+    w.EndArray();
+    NS_ConvertUTF8toUTF16 buffer16(buffer.StringCRef());
+    MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx,
+                                 static_cast<const char16_t*>(buffer16.get()),
+                                 buffer16.Length(), &val));
+  }
+  JS::Rooted<JSObject*> obj(aCx, &val.toObject());
+  if (!obj) {
+    return NS_ERROR_FAILURE;
+  }
+  aResult.setObject(*obj);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetActiveConfiguration(JSContext* aCx,
+                                   JS::MutableHandle<JS::Value> aResult) {
+  JS::Rooted<JS::Value> jsValue(aCx);
+  {
+    JSONStringWriteFunc<nsCString> buffer;
+    JSONWriter writer(buffer, JSONWriter::SingleLineStyle);
+    profiler_write_active_configuration(writer);
+    NS_ConvertUTF8toUTF16 buffer16(buffer.StringCRef());
+    MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx,
+                                 static_cast<const char16_t*>(buffer16.get()),
+                                 buffer16.Length(), &jsValue));
+  }
+  if (jsValue.isNull()) {
+    aResult.setNull();
+  } else {
+    JS::Rooted<JSObject*> obj(aCx, &jsValue.toObject());
+    if (!obj) {
+      return NS_ERROR_FAILURE;
+    }
+    aResult.setObject(*obj);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::DumpProfileToFile(const char* aFilename) {
+  profiler_save_profile_to_file(aFilename);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileData(double aSinceTime, JSContext* aCx,
+                           JS::MutableHandle<JS::Value> aResult) {
+  mozilla::UniquePtr<char[]> profile = profiler_get_profile(aSinceTime);
+  if (!profile) {
+    return NS_ERROR_FAILURE;
+  }
+
+  NS_ConvertUTF8toUTF16 js_string(nsDependentCString(profile.get()));
+  auto profile16 = static_cast<const char16_t*>(js_string.get());
+
+  JS::Rooted<JS::Value> val(aCx);
+  MOZ_ALWAYS_TRUE(JS_ParseJSON(aCx, profile16, js_string.Length(), &val));
+
+  aResult.set(val);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsync(double aSinceTime, JSContext* aCx,
+                                Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+
+            // Now parse the JSON so that we resolve with a JS Object.
+            JS::Rooted<JS::Value> val(cx);
+            {
+              NS_ConvertUTF8toUTF16 js_string(aResult.mProfile);
+              if (!JS_ParseJSON(cx,
+                                static_cast<const char16_t*>(js_string.get()),
+                                js_string.Length(), &val)) {
+                if (!jsapi.HasException()) {
+                  promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+                } else {
+                  JS::Rooted<JS::Value> exn(cx);
+                  DebugOnly<bool> gotException = jsapi.StealException(&exn);
+                  MOZ_ASSERT(gotException);
+
+                  jsapi.ClearException();
+                  promise->MaybeReject(exn);
+                }
+              } else {
+                promise->MaybeResolve(val);
+              }
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsArrayBuffer(double aSinceTime, JSContext* aCx,
+                                        Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+            JSObject* typedArray = dom::ArrayBuffer::Create(
+                cx, aResult.mProfile.Length(),
+                reinterpret_cast<const uint8_t*>(aResult.mProfile.Data()));
+            if (typedArray) {
+              JS::Rooted<JS::Value> val(cx, JS::ObjectValue(*typedArray));
+              promise->MaybeResolve(val);
+            } else {
+              promise->MaybeReject(NS_ERROR_OUT_OF_MEMORY);
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+nsresult CompressString(const nsCString& aString,
+                        FallibleTArray<uint8_t>& aOutBuff) {
+  // Compress a buffer via zlib (as with `compress()`), but emit a
+  // gzip header as well. Like `compress()`, this is limited to 4GB in
+  // size, but that shouldn't be an issue for our purposes.
+  uLongf outSize = compressBound(aString.Length());
+  if (!aOutBuff.SetLength(outSize, fallible)) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  int zerr;
+  z_stream stream;
+  stream.zalloc = nullptr;
+  stream.zfree = nullptr;
+  stream.opaque = nullptr;
+  stream.next_out = (Bytef*)aOutBuff.Elements();
+  stream.avail_out = aOutBuff.Length();
+  stream.next_in = (z_const Bytef*)aString.Data();
+  stream.avail_in = aString.Length();
+
+  // A windowBits of 31 is the default (15) plus 16 for emitting a
+  // gzip header; a memLevel of 8 is the default.
+  zerr =
+      deflateInit2(&stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
+                   /* windowBits */ 31, /* memLevel */ 8, Z_DEFAULT_STRATEGY);
+  if (zerr != Z_OK) {
+    return NS_ERROR_FAILURE;
+  }
+
+  zerr = deflate(&stream, Z_FINISH);
+  outSize = stream.total_out;
+  deflateEnd(&stream);
+
+  if (zerr != Z_STREAM_END) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aOutBuff.TruncateLength(outSize);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetProfileDataAsGzippedArrayBuffer(double aSinceTime,
+                                               JSContext* aCx,
+                                               Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            FallibleTArray<uint8_t> outBuff;
+            nsresult result = CompressString(aResult.mProfile, outBuff);
+
+            if (result != NS_OK) {
+              promise->MaybeReject(result);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+            // Get the profile typedArray.
+            JSObject* typedArray = dom::ArrayBuffer::Create(
+                cx, outBuff.Length(), outBuff.Elements());
+            if (!typedArray) {
+              promise->MaybeReject(NS_ERROR_OUT_OF_MEMORY);
+              return;
+            }
+            JS::Rooted<JS::Value> typedArrayValue(cx,
+                                                  JS::ObjectValue(*typedArray));
+            // Get the additional information object.
+            JS::Rooted<JS::Value> additionalInfoVal(cx);
+            if (aResult.mAdditionalInformation.isSome()) {
+              aResult.mAdditionalInformation->ToJSValue(cx, &additionalInfoVal);
+            } else {
+              additionalInfoVal.setUndefined();
+            }
+
+            // Create the return object.
+            JS::Rooted<JSObject*> resultObj(cx, JS_NewPlainObject(cx));
+            JS_SetProperty(cx, resultObj, "profile", typedArrayValue);
+            JS_SetProperty(cx, resultObj, "additionalInformation",
+                           additionalInfoVal);
+            promise->MaybeResolve(resultObj);
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::DumpProfileToFileAsync(const nsACString& aFilename,
+                                   double aSinceTime, JSContext* aCx,
+                                   Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject = xpc::CurrentNativeGlobal(aCx);
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  nsCString filename(aFilename);
+
+  StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [filename,
+           promise](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            if (aResult.mProfile.Length() >=
+                size_t(std::numeric_limits<std::streamsize>::max())) {
+              promise->MaybeReject(NS_ERROR_FILE_TOO_BIG);
+              return;
+            }
+
+            std::ofstream stream;
+            stream.open(filename.get());
+            if (!stream.is_open()) {
+              promise->MaybeReject(NS_ERROR_FILE_UNRECOGNIZED_PATH);
+              return;
+            }
+
+            stream.write(aResult.mProfile.get(),
+                         std::streamsize(aResult.mProfile.Length()));
+            stream.close();
+
+            promise->MaybeResolveWithUndefined();
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetSymbolTable(const nsACString& aDebugPath,
+                           const nsACString& aBreakpadID, JSContext* aCx,
+                           Promise** aPromise) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (NS_WARN_IF(!aCx)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsIGlobalObject* globalObject =
+      xpc::NativeGlobal(JS::CurrentGlobalOrNull(aCx));
+
+  if (NS_WARN_IF(!globalObject)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  ErrorResult result;
+  RefPtr<Promise> promise = Promise::Create(globalObject, result);
+  if (NS_WARN_IF(result.Failed())) {
+    return result.StealNSResult();
+  }
+
+  GetSymbolTableMozPromise(aDebugPath, aBreakpadID)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [promise](const SymbolTable& aSymbolTable) {
+            AutoJSAPI jsapi;
+            if (NS_WARN_IF(!jsapi.Init(promise->GetGlobalObject()))) {
+              // We're really hosed if we can't get a JS context for some
+              // reason.
+              promise->MaybeReject(NS_ERROR_DOM_UNKNOWN_ERR);
+              return;
+            }
+
+            JSContext* cx = jsapi.cx();
+
+            JS::Rooted<JSObject*> addrsArray(
+                cx, dom::Uint32Array::Create(cx, aSymbolTable.mAddrs.Length(),
+                                             aSymbolTable.mAddrs.Elements()));
+            JS::Rooted<JSObject*> indexArray(
+                cx, dom::Uint32Array::Create(cx, aSymbolTable.mIndex.Length(),
+                                             aSymbolTable.mIndex.Elements()));
+            JS::Rooted<JSObject*> bufferArray(
+                cx, dom::Uint8Array::Create(cx, aSymbolTable.mBuffer.Length(),
+                                            aSymbolTable.mBuffer.Elements()));
+
+            if (addrsArray && indexArray && bufferArray) {
+              JS::Rooted<JSObject*> tuple(cx, JS::NewArrayObject(cx, 3));
+              JS_SetElement(cx, tuple, 0, addrsArray);
+              JS_SetElement(cx, tuple, 1, indexArray);
+              JS_SetElement(cx, tuple, 2, bufferArray);
+              promise->MaybeResolve(tuple);
+            } else {
+              promise->MaybeReject(NS_ERROR_FAILURE);
+            }
+          },
+          [promise](nsresult aRv) { promise->MaybeReject(aRv); });
+
+  promise.forget(aPromise);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetElapsedTime(double* aElapsedTime) {
+  *aElapsedTime = profiler_time();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::IsActive(bool* aIsActive) {
+  *aIsActive = profiler_is_active();
+  return NS_OK;
+}
+
+static void GetArrayOfStringsForFeatures(uint32_t aFeatures,
+                                         nsTArray<nsCString>& aFeatureList) {
+#define COUNT_IF_SET(n_, str_, Name_, desc_)    \
+  if (ProfilerFeature::Has##Name_(aFeatures)) { \
+    len++;                                      \
+  }
+
+  // Count the number of features in use.
+  uint32_t len = 0;
+  PROFILER_FOR_EACH_FEATURE(COUNT_IF_SET)
+
+#undef COUNT_IF_SET
+
+  aFeatureList.SetCapacity(len);
+
+#define DUP_IF_SET(n_, str_, Name_, desc_)      \
+  if (ProfilerFeature::Has##Name_(aFeatures)) { \
+    aFeatureList.AppendElement(str_);           \
+  }
+
+  // Insert the strings for the features in use.
+  PROFILER_FOR_EACH_FEATURE(DUP_IF_SET)
+
+#undef DUP_IF_SET
+}
+
+NS_IMETHODIMP
+nsProfiler::GetFeatures(nsTArray<nsCString>& aFeatureList) {
+  uint32_t features = profiler_get_available_features();
+  GetArrayOfStringsForFeatures(features, aFeatureList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetAllFeatures(nsTArray<nsCString>& aFeatureList) {
+  GetArrayOfStringsForFeatures((uint32_t)-1, aFeatureList);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfiler::GetBufferInfo(uint32_t* aCurrentPosition, uint32_t* aTotalSize,
+                          uint32_t* aGeneration) {
+  MOZ_ASSERT(aCurrentPosition);
+  MOZ_ASSERT(aTotalSize);
+  MOZ_ASSERT(aGeneration);
+  Maybe<ProfilerBufferInfo> info = profiler_get_buffer_info();
+  if (info) {
+    *aCurrentPosition = info->mRangeEnd % info->mEntryCount;
+    *aTotalSize = info->mEntryCount;
+    *aGeneration = info->mRangeEnd / info->mEntryCount;
+  } else {
+    *aCurrentPosition = 0;
+    *aTotalSize = 0;
+    *aGeneration = 0;
+  }
+  return NS_OK;
+}
+
+bool nsProfiler::SendProgressRequest(PendingProfile& aPendingProfile) {
+  RefPtr<ProfilerParent::SingleProcessProgressPromise> progressPromise =
+      ProfilerParent::RequestGatherProfileProgress(aPendingProfile.childPid);
+  if (!progressPromise) {
+    LOG("RequestGatherProfileProgress(%u) -> null!",
+        unsigned(aPendingProfile.childPid));
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(
+          Json::StaticString{"Failed to send progress request to pid:"});
+      aEvent.append(Json::Value::UInt64(aPendingProfile.childPid));
+    });
+    // Failed to send request.
+    return false;
+  }
+
+  DEBUG_LOG("RequestGatherProfileProgress(%u) sent...",
+            unsigned(aPendingProfile.childPid));
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{"Requested progress from pid:"});
+    aEvent.append(Json::Value::UInt64(aPendingProfile.childPid));
+  });
+  aPendingProfile.lastProgressRequest = TimeStamp::Now();
+  progressPromise->Then(
+      GetMainThreadSerialEventTarget(), __func__,
+      [self = RefPtr<nsProfiler>(this),
+       childPid = aPendingProfile.childPid](GatherProfileProgress&& aResult) {
+        if (!self->mGathering) {
+          return;
+        }
+        PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+        DEBUG_LOG(
+            "RequestGatherProfileProgress(%u) response: %.2f '%s' "
+            "(%u were pending, %s %u)",
+            unsigned(childPid),
+            ProportionValue::FromUnderlyingType(
+                aResult.progressProportionValueUnderlyingType())
+                    .ToDouble() *
+                100.0,
+            aResult.progressLocation().Data(),
+            unsigned(self->mPendingProfiles.length()),
+            pendingProfile ? "including" : "excluding", unsigned(childPid));
+        self->LogEvent([&](Json::Value& aEvent) {
+          aEvent.append(
+              Json::StaticString{"Got response from pid, with progress:"});
+          aEvent.append(Json::Value::UInt64(childPid));
+          aEvent.append(
+              Json::Value{ProportionValue::FromUnderlyingType(
+                              aResult.progressProportionValueUnderlyingType())
+                              .ToDouble() *
+                          100.0});
+        });
+        if (pendingProfile) {
+          // We have a progress report for a still-pending profile.
+          pendingProfile->lastProgressResponse = TimeStamp::Now();
+          // Has it actually made progress?
+          if (aResult.progressProportionValueUnderlyingType() !=
+              pendingProfile->progressProportion.ToUnderlyingType()) {
+            pendingProfile->lastProgressChange =
+                pendingProfile->lastProgressResponse;
+            pendingProfile->progressProportion =
+                ProportionValue::FromUnderlyingType(
+                    aResult.progressProportionValueUnderlyingType());
+            pendingProfile->progressLocation = aResult.progressLocation();
+            self->RestartGatheringTimer();
+          }
+        }
+      },
+      [self = RefPtr<nsProfiler>(this), childPid = aPendingProfile.childPid](
+          ipc::ResponseRejectReason&& aReason) {
+        if (!self->mGathering) {
+          return;
+        }
+        PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+        LOG("RequestGatherProfileProgress(%u) rejection: %d "
+            "(%u were pending, %s %u)",
+            unsigned(childPid), (int)aReason,
+            unsigned(self->mPendingProfiles.length()),
+            pendingProfile ? "including" : "excluding", unsigned(childPid));
+        self->LogEvent([&](Json::Value& aEvent) {
+          aEvent.append(Json::StaticString{
+              "Got progress request rejection from pid, with reason:"});
+          aEvent.append(Json::Value::UInt64(childPid));
+          aEvent.append(Json::Value::UInt{static_cast<unsigned>(aReason)});
+        });
+        if (pendingProfile) {
+          // Failure response, assume the child process is gone.
+          MOZ_ASSERT(self->mPendingProfiles.begin() <= pendingProfile &&
+                     pendingProfile < self->mPendingProfiles.end());
+          self->mPendingProfiles.erase(pendingProfile);
+          if (self->mPendingProfiles.empty()) {
+            // We've got all of the async profiles now. Let's finish off the
+            // profile and resolve the Promise.
+            self->FinishGathering();
+          }
+        }
+      });
+  return true;
+}
+
+/* static */ void nsProfiler::GatheringTimerCallback(nsITimer* aTimer,
+                                                     void* aClosure) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  nsCOMPtr<nsIProfiler> profiler(
+      do_GetService("@mozilla.org/tools/profiler;1"));
+  if (!profiler) {
+    // No (more) profiler service.
+    return;
+  }
+  nsProfiler* self = static_cast<nsProfiler*>(profiler.get());
+  if (self != aClosure) {
+    // Different service object!?
+    return;
+  }
+  if (aTimer != self->mGatheringTimer) {
+    // This timer was cancelled after this callback was queued.
+    return;
+  }
+
+  bool progressWasMade = false;
+
+  // Going backwards, it's easier and cheaper to erase elements if needed.
+  for (auto iPlus1 = self->mPendingProfiles.length(); iPlus1 != 0; --iPlus1) {
+    PendingProfile& pendingProfile = self->mPendingProfiles[iPlus1 - 1];
+
+    bool needToSendProgressRequest = false;
+    if (pendingProfile.lastProgressRequest.IsNull()) {
+      DEBUG_LOG("GatheringTimerCallback() - child %u: No data yet",
+                unsigned(pendingProfile.childPid));
+      // First time going through the list, send an initial progress request.
+      needToSendProgressRequest = true;
+      // We pretend that progress was made, so we don't give up yet.
+      progressWasMade = true;
+    } else if (pendingProfile.lastProgressResponse.IsNull()) {
+      LOG("GatheringTimerCallback() - child %u: Waiting for first response",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for the first response, no progress made here, don't send
+      // another request.
+    } else if (pendingProfile.lastProgressResponse <=
+               pendingProfile.lastProgressRequest) {
+      LOG("GatheringTimerCallback() - child %u: Waiting for response",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for a response to the last request, no progress made
+      // here, don't send another request.
+    } else if (pendingProfile.lastProgressChange.IsNull()) {
+      LOG("GatheringTimerCallback() - child %u: Still waiting for first change",
+          unsigned(pendingProfile.childPid));
+      // Still waiting for the first change, no progress made here, but send a
+      // new request.
+      needToSendProgressRequest = true;
+    } else if (pendingProfile.lastProgressRequest <
+               pendingProfile.lastProgressChange) {
+      DEBUG_LOG("GatheringTimerCallback() - child %u: Recent change",
+                unsigned(pendingProfile.childPid));
+      // We have a recent change, progress was made.
+      needToSendProgressRequest = true;
+      progressWasMade = true;
+    } else {
+      LOG("GatheringTimerCallback() - child %u: No recent change",
+          unsigned(pendingProfile.childPid));
+      needToSendProgressRequest = true;
+    }
+
+    // And send a new progress request.
+    if (needToSendProgressRequest) {
+      if (!self->SendProgressRequest(pendingProfile)) {
+        // Failed to even send the request, consider this process gone.
+        self->mPendingProfiles.erase(&pendingProfile);
+        LOG("... Failed to send progress request");
+      } else {
+        DEBUG_LOG("... Sent progress request");
+      }
+    } else {
+      DEBUG_LOG("... No progress request");
+    }
+  }
+
+  if (self->mPendingProfiles.empty()) {
+    // We've got all of the async profiles now. Let's finish off the profile
+    // and resolve the Promise.
+    self->FinishGathering();
+    return;
+  }
+
+  // Not finished yet.
+
+  if (progressWasMade) {
+    // We made some progress, just restart the timer.
+    DEBUG_LOG("GatheringTimerCallback() - Progress made, restart timer");
+    self->RestartGatheringTimer();
+    return;
+  }
+
+  DEBUG_LOG("GatheringTimerCallback() - Timeout!");
+  self->mGatheringTimer = nullptr;
+  if (!profiler_is_active() || !self->mGathering) {
+    // Not gathering anymore.
+    return;
+  }
+  self->LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(Json::StaticString{
+        "No progress made recently, giving up; pending pids:"});
+    for (const PendingProfile& pendingProfile : self->mPendingProfiles) {
+      aEvent.append(Json::Value::UInt64(pendingProfile.childPid));
+    }
+  });
+  NS_WARNING("Profiler failed to gather profiles from all sub-processes");
+  // We have really reached a timeout while gathering, finish now.
+  // TODO: Add information about missing processes.
+  self->FinishGathering();
+}
+
+void nsProfiler::RestartGatheringTimer() {
+  if (mGatheringTimer) {
+    uint32_t delayMs = 0;
+    const nsresult r = mGatheringTimer->GetDelay(&delayMs);
+    mGatheringTimer->Cancel();
+    if (NS_FAILED(r) || delayMs == 0 ||
+        NS_FAILED(mGatheringTimer->InitWithNamedFuncCallback(
+            GatheringTimerCallback, this, delayMs,
+            nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY,
+            "nsProfilerGatheringTimer"))) {
+      // Can't restart the timer, so we can't wait any longer.
+      FinishGathering();
+    }
+  }
+}
+
+nsProfiler::PendingProfile* nsProfiler::GetPendingProfile(
+    base::ProcessId aChildPid) {
+  for (PendingProfile& pendingProfile : mPendingProfiles) {
+    if (pendingProfile.childPid == aChildPid) {
+      return &pendingProfile;
+    }
+  }
+  return nullptr;
+}
+
+void nsProfiler::GatheredOOPProfile(
+    base::ProcessId aChildPid, const nsACString& aProfile,
+    mozilla::Maybe<ProfileGenerationAdditionalInformation>&&
+        aAdditionalInformation) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return;
+  }
+
+  if (!mGathering) {
+    // If we're not actively gathering, then we don't actually care that we
+    // gathered a profile here. This can happen for processes that exit while
+    // profiling.
+    return;
+  }
+
+  MOZ_RELEASE_ASSERT(mWriter.isSome(),
+                     "Should always have a writer if mGathering is true");
+
+  // Combine all the additional information into a single struct.
+  if (aAdditionalInformation.isSome()) {
+    mProfileGenerationAdditionalInformation->Append(
+        std::move(*aAdditionalInformation));
+  }
+
+  if (!aProfile.IsEmpty()) {
+    if (mWriter->ChunkedWriteFunc().Length() + aProfile.Length() <
+        scLengthAccumulationThreshold) {
+      // TODO: Remove PromiseFlatCString, see bug 1657033.
+      mWriter->Splice(PromiseFlatCString(aProfile));
+    } else {
+      LogEvent([&](Json::Value& aEvent) {
+        aEvent.append(
+            Json::StaticString{"Discarded child profile that would make the "
+                               "full profile too big, pid and size:"});
+        aEvent.append(Json::Value::UInt64(aChildPid));
+        aEvent.append(Json::Value::UInt64{aProfile.Length()});
+      });
+    }
+  }
+
+  if (PendingProfile* pendingProfile = GetPendingProfile(aChildPid);
+      pendingProfile) {
+    mPendingProfiles.erase(pendingProfile);
+
+    if (mPendingProfiles.empty()) {
+      // We've got all of the async profiles now. Let's finish off the profile
+      // and resolve the Promise.
+      FinishGathering();
+    }
+  }
+
+  // Not finished yet, restart the timer to let any remaining child enough time
+  // to do their profile-streaming.
+  RestartGatheringTimer();
+}
+
+RefPtr<nsProfiler::GatheringPromiseAndroid>
+nsProfiler::GetProfileDataAsGzippedArrayBufferAndroid(double aSinceTime) {
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!profiler_is_active()) {
+    return GatheringPromiseAndroid::CreateAndReject(NS_ERROR_FAILURE, __func__);
+  }
+
+  return StartGathering(aSinceTime)
+      ->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [](const mozilla::ProfileAndAdditionalInformation& aResult) {
+            FallibleTArray<uint8_t> outBuff;
+            nsresult result = CompressString(aResult.mProfile, outBuff);
+            if (result != NS_OK) {
+              return GatheringPromiseAndroid::CreateAndReject(result, __func__);
+            }
+            return GatheringPromiseAndroid::CreateAndResolve(std::move(outBuff),
+                                                             __func__);
+          },
+          [](nsresult aRv) {
+            return GatheringPromiseAndroid::CreateAndReject(aRv, __func__);
+          });
+}
+
+RefPtr<nsProfiler::GatheringPromise> nsProfiler::StartGathering(
+    double aSinceTime) {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+
+  if (mGathering) {
+    // If we're already gathering, return a rejected promise - this isn't
+    // going to end well.
+    return GatheringPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE, __func__);
+  }
+
+  mGathering = true;
+  mGatheringLog = mozilla::MakeUnique<Json::Value>(Json::objectValue);
+  (*mGatheringLog)[Json::StaticString{
+      "profileGatheringLogBegin" TIMESTAMP_JSON_SUFFIX}] =
+      ProfilingLog::Timestamp();
+
+  if (mGatheringTimer) {
+    mGatheringTimer->Cancel();
+    mGatheringTimer = nullptr;
+  }
+
+  // Start building shared library info starting from the current process.
+  mProfileGenerationAdditionalInformation.emplace(
+      SharedLibraryInfo::GetInfoForSelf());
+
+  // Request profiles from the other processes. This will trigger asynchronous
+  // calls to ProfileGatherer::GatheredOOPProfile as the profiles arrive.
+  //
+  // Do this before the call to profiler_stream_json_for_this_process() because
+  // that call is slow and we want to let the other processes grab their
+  // profiles as soon as possible.
+  nsTArray<ProfilerParent::SingleProcessProfilePromiseAndChildPid> profiles =
+      ProfilerParent::GatherProfiles();
+
+  MOZ_ASSERT(mPendingProfiles.empty());
+  if (!mPendingProfiles.reserve(profiles.Length())) {
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return GatheringPromise::CreateAndReject(NS_ERROR_OUT_OF_MEMORY, __func__);
+  }
+
+  mFailureLatchSource.emplace();
+  mWriter.emplace(*mFailureLatchSource);
+
+  UniquePtr<ProfilerCodeAddressService> service =
+      profiler_code_address_service_for_presymbolication();
+
+  // Start building up the JSON result and grab the profile from this process.
+  mWriter->Start();
+  auto rv = profiler_stream_json_for_this_process(*mWriter, aSinceTime,
+                                                  /* aIsShuttingDown */ false,
+                                                  service.get());
+  if (rv.isErr()) {
+    // The profiler is inactive. This either means that it was inactive even
+    // at the time that ProfileGatherer::Start() was called, or that it was
+    // stopped on a different thread since that call. Either way, we need to
+    // reject the promise and stop gathering.
+    ResetGathering(NS_ERROR_NOT_AVAILABLE);
+    return GatheringPromise::CreateAndReject(NS_ERROR_NOT_AVAILABLE, __func__);
+  }
+
+  LogEvent([&](Json::Value& aEvent) {
+    aEvent.append(
+        Json::StaticString{"Generated parent process profile, size:"});
+    aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+  });
+
+  mWriter->StartArrayProperty("processes");
+
+  // If we have any process exit profiles, add them immediately.
+  if (Vector<nsCString> exitProfiles = profiler_move_exit_profiles();
+      !exitProfiles.empty()) {
+    for (auto& exitProfile : exitProfiles) {
+      if (!exitProfile.IsEmpty()) {
+        if (exitProfile[0] == '*') {
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(
+                Json::StaticString{"Exit non-profile with error message:"});
+            aEvent.append(exitProfile.Data() + 1);
+          });
+        } else if (mWriter->ChunkedWriteFunc().Length() + exitProfile.Length() <
+                   scLengthAccumulationThreshold) {
+          mWriter->Splice(exitProfile);
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(Json::StaticString{"Added exit profile with size:"});
+            aEvent.append(Json::Value::UInt64{exitProfile.Length()});
+          });
+        } else {
+          LogEvent([&](Json::Value& aEvent) {
+            aEvent.append(
+                Json::StaticString{"Discarded an exit profile that would make "
+                                   "the full profile too big, size:"});
+            aEvent.append(Json::Value::UInt64{exitProfile.Length()});
+          });
+        }
+      }
+    }
+
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(Json::StaticString{
+          "Processed all exit profiles, total size so far:"});
+      aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+    });
+  } else {
+    // There are no pending profiles, we're already done.
+    LogEventLiteralString("No exit profiles.");
+  }
+
+  mPromiseHolder.emplace();
+  RefPtr<GatheringPromise> promise = mPromiseHolder->Ensure(__func__);
+
+  // Keep the array property "processes" and the root object in mWriter open
+  // until FinishGathering() is called. As profiles from the other processes
+  // come in, they will be inserted and end up in the right spot.
+  // FinishGathering() will close the array and the root object.
+
+  if (!profiles.IsEmpty()) {
+    // There *are* pending profiles, let's add handlers for their promises.
+
+    // This timeout value is used to monitor progress while gathering child
+    // profiles. The timer will be restarted after we receive a response with
+    // any progress.
+    constexpr uint32_t cMinChildTimeoutS = 1u;  // 1 second minimum and default.
+    constexpr uint32_t cMaxChildTimeoutS = 60u;  // 1 minute max.
+    uint32_t childTimeoutS = Preferences::GetUint(
+        "devtools.performance.recording.child.timeout_s", cMinChildTimeoutS);
+    if (childTimeoutS < cMinChildTimeoutS) {
+      childTimeoutS = cMinChildTimeoutS;
+    } else if (childTimeoutS > cMaxChildTimeoutS) {
+      childTimeoutS = cMaxChildTimeoutS;
+    }
+    const uint32_t childTimeoutMs = childTimeoutS * PR_MSEC_PER_SEC;
+    Unused << NS_NewTimerWithFuncCallback(
+        getter_AddRefs(mGatheringTimer), GatheringTimerCallback, this,
+        childTimeoutMs, nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY,
+        "nsProfilerGatheringTimer", GetMainThreadSerialEventTarget());
+
+    MOZ_ASSERT(mPendingProfiles.capacity() >= profiles.Length());
+    for (const auto& profile : profiles) {
+      mPendingProfiles.infallibleAppend(PendingProfile{profile.childPid});
+      LogEvent([&](Json::Value& aEvent) {
+        aEvent.append(Json::StaticString{"Waiting for pending profile, pid:"});
+        aEvent.append(Json::Value::UInt64(profile.childPid));
+      });
+      profile.profilePromise->Then(
+          GetMainThreadSerialEventTarget(), __func__,
+          [self = RefPtr<nsProfiler>(this), childPid = profile.childPid](
+              IPCProfileAndAdditionalInformation&& aResult) {
+            PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+            mozilla::ipc::Shmem profileShmem = aResult.profileShmem();
+            LOG("GatherProfile(%u) response: %u bytes (%u were pending, %s %u)",
+                unsigned(childPid), unsigned(profileShmem.Size<char>()),
+                unsigned(self->mPendingProfiles.length()),
+                pendingProfile ? "including" : "excluding", unsigned(childPid));
+            if (profileShmem.IsReadable()) {
+              self->LogEvent([&](Json::Value& aEvent) {
+                aEvent.append(
+                    Json::StaticString{"Got profile from pid, with size:"});
+                aEvent.append(Json::Value::UInt64(childPid));
+                aEvent.append(Json::Value::UInt64{profileShmem.Size<char>()});
+              });
+              const nsDependentCSubstring profileString(
+                  profileShmem.get<char>(), profileShmem.Size<char>() - 1);
+              if (profileString.IsEmpty() || profileString[0] != '*') {
+                self->GatheredOOPProfile(
+                    childPid, profileString,
+                    std::move(aResult.additionalInformation()));
+              } else {
+                self->LogEvent([&](Json::Value& aEvent) {
+                  aEvent.append(Json::StaticString{
+                      "Child non-profile from pid, with error message:"});
+                  aEvent.append(Json::Value::UInt64(childPid));
+                  aEvent.append(profileString.Data() + 1);
+                });
+                self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+              }
+            } else {
+              // This can happen if the child failed to allocate
+              // the Shmem (or maliciously sent an invalid Shmem).
+              self->LogEvent([&](Json::Value& aEvent) {
+                aEvent.append(Json::StaticString{"Got failure from pid:"});
+                aEvent.append(Json::Value::UInt64(childPid));
+              });
+              self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+            }
+          },
+          [self = RefPtr<nsProfiler>(this),
+           childPid = profile.childPid](ipc::ResponseRejectReason&& aReason) {
+            PendingProfile* pendingProfile = self->GetPendingProfile(childPid);
+            LOG("GatherProfile(%u) rejection: %d (%u were pending, %s %u)",
+                unsigned(childPid), (int)aReason,
+                unsigned(self->mPendingProfiles.length()),
+                pendingProfile ? "including" : "excluding", unsigned(childPid));
+            self->LogEvent([&](Json::Value& aEvent) {
+              aEvent.append(
+                  Json::StaticString{"Got rejection from pid, with reason:"});
+              aEvent.append(Json::Value::UInt64(childPid));
+              aEvent.append(Json::Value::UInt{static_cast<unsigned>(aReason)});
+            });
+            self->GatheredOOPProfile(childPid, ""_ns, Nothing());
+          });
+    }
+  } else {
+    // There are no pending profiles, we're already done.
+    LogEventLiteralString("No pending child profiles.");
+    FinishGathering();
+  }
+
+  return promise;
+}
+
+RefPtr<nsProfiler::SymbolTablePromise> nsProfiler::GetSymbolTableMozPromise(
+    const nsACString& aDebugPath, const nsACString& aBreakpadID) {
+  MozPromiseHolder<SymbolTablePromise> promiseHolder;
+  RefPtr<SymbolTablePromise> promise = promiseHolder.Ensure(__func__);
+
+  if (!mSymbolTableThread) {
+    nsresult rv = NS_NewNamedThread("ProfSymbolTable",
+                                    getter_AddRefs(mSymbolTableThread));
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+      promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+      return promise;
+    }
+  }
+
+  nsresult rv = mSymbolTableThread->Dispatch(NS_NewRunnableFunction(
+      "nsProfiler::GetSymbolTableMozPromise runnable on ProfSymbolTable thread",
+      [promiseHolder = std::move(promiseHolder),
+       debugPath = nsCString(aDebugPath),
+       breakpadID = nsCString(aBreakpadID)]() mutable {
+        AUTO_PROFILER_LABEL_DYNAMIC_NSCSTRING("profiler_get_symbol_table",
+                                              OTHER, debugPath);
+        SymbolTable symbolTable;
+        bool succeeded = profiler_get_symbol_table(
+            debugPath.get(), breakpadID.get(), &symbolTable);
+        if (succeeded) {
+          promiseHolder.Resolve(std::move(symbolTable), __func__);
+        } else {
+          promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+        }
+      }));
+
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+    // Get-symbol task was not dispatched and therefore won't fulfill the
+    // promise, we must reject the promise now.
+    promiseHolder.Reject(NS_ERROR_FAILURE, __func__);
+  }
+
+  return promise;
+}
+
+void nsProfiler::FinishGathering() {
+  MOZ_RELEASE_ASSERT(NS_IsMainThread());
+  MOZ_RELEASE_ASSERT(mWriter.isSome());
+  MOZ_RELEASE_ASSERT(mPromiseHolder.isSome());
+  MOZ_RELEASE_ASSERT(mProfileGenerationAdditionalInformation.isSome());
+
+  // Close the "processes" array property.
+  mWriter->EndArray();
+
+  if (mGatheringLog) {
+    LogEvent([&](Json::Value& aEvent) {
+      aEvent.append(Json::StaticString{"Finished gathering, total size:"});
+      aEvent.append(Json::Value::UInt64{mWriter->ChunkedWriteFunc().Length()});
+    });
+    (*mGatheringLog)[Json::StaticString{
+        "profileGatheringLogEnd" TIMESTAMP_JSON_SUFFIX}] =
+        ProfilingLog::Timestamp();
+    mWriter->StartObjectProperty("profileGatheringLog");
+    {
+      nsAutoCString pid;
+      pid.AppendInt(int64_t(profiler_current_process_id().ToNumber()));
+      Json::String logString = ToCompactString(*mGatheringLog);
+      mGatheringLog = nullptr;
+      mWriter->SplicedJSONProperty(pid, logString);
+    }
+    mWriter->EndObject();
+  }
+
+  // Close the root object of the generated JSON.
+  mWriter->End();
+
+  if (const char* failure = mWriter->GetFailure(); failure) {
+#ifndef ANDROID
+    fprintf(stderr, "JSON generation failure: %s", failure);
+#else
+    __android_log_print(ANDROID_LOG_INFO, "GeckoProfiler",
+                        "JSON generation failure: %s", failure);
+#endif
+    NS_WARNING("Error during JSON generation, probably OOM.");
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+
+  // And try to resolve the promise with the profile JSON.
+  const size_t len = mWriter->ChunkedWriteFunc().Length();
+  if (len >= scLengthMax) {
+    NS_WARNING("Profile JSON is too big to fit in a string.");
+    ResetGathering(NS_ERROR_FILE_TOO_BIG);
+    return;
+  }
+
+  nsCString result;
+  if (!result.SetLength(len, fallible)) {
+    NS_WARNING("Cannot allocate a string for the Profile JSON.");
+    ResetGathering(NS_ERROR_OUT_OF_MEMORY);
+    return;
+  }
+  MOZ_ASSERT(*(result.Data() + len) == '\0',
+             "We expected a null at the end of the string buffer, to be "
+             "rewritten by CopyDataIntoLazilyAllocatedBuffer");
+
+  char* const resultBeginWriting = result.BeginWriting();
+  if (!resultBeginWriting) {
+    NS_WARNING("Cannot access the string to write the Profile JSON.");
+    ResetGathering(NS_ERROR_CACHE_WRITE_ACCESS_DENIED);
+    return;
+  }
+
+  // Here, we have enough space reserved in `result`, starting at
+  // `resultBeginWriting`, copy the JSON profile there.
+  if (!mWriter->ChunkedWriteFunc().CopyDataIntoLazilyAllocatedBuffer(
+          [&](size_t aBufferLen) -> char* {
+            MOZ_RELEASE_ASSERT(aBufferLen == len + 1);
+            return resultBeginWriting;
+          })) {
+    NS_WARNING("Could not copy profile JSON, probably OOM.");
+    ResetGathering(NS_ERROR_FILE_TOO_BIG);
+    return;
+  }
+  MOZ_ASSERT(*(result.Data() + len) == '\0',
+             "We still expected a null at the end of the string buffer");
+
+  mProfileGenerationAdditionalInformation->FinishGathering();
+  mPromiseHolder->Resolve(
+      ProfileAndAdditionalInformation{
+          std::move(result),
+          std::move(*mProfileGenerationAdditionalInformation)},
+      __func__);
+
+  ResetGathering(NS_ERROR_UNEXPECTED);
+}
+
+void nsProfiler::ResetGathering(nsresult aPromiseRejectionIfPending) {
+  // If we have an unfulfilled Promise in flight, we should reject it before
+  // destroying the promise holder.
+  if (mPromiseHolder.isSome()) {
+    mPromiseHolder->RejectIfExists(aPromiseRejectionIfPending, __func__);
+    mPromiseHolder.reset();
+  }
+  mPendingProfiles.clearAndFree();
+  mGathering = false;
+  mGatheringLog = nullptr;
+  if (mGatheringTimer) {
+    mGatheringTimer->Cancel();
+    mGatheringTimer = nullptr;
+  }
+  mWriter.reset();
+  mFailureLatchSource.reset();
+  mProfileGenerationAdditionalInformation.reset();
+}
diff --git a/tools/profiler/gecko/nsProfiler.h b/tools/profiler/gecko/nsProfiler.h
new file mode 100644
index 0000000000..3757df3079
--- /dev/null
+++ b/tools/profiler/gecko/nsProfiler.h
@@ -0,0 +1,117 @@
+/* -*- 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 nsProfiler_h
+#define nsProfiler_h
+
+#include "base/process.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/ProfileJSONWriter.h"
+#include "mozilla/ProportionValue.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Vector.h"
+#include "nsIProfiler.h"
+#include "nsITimer.h"
+#include "nsServiceManagerUtils.h"
+#include "ProfilerCodeAddressService.h"
+#include "ProfileAdditionalInformation.h"
+
+namespace Json {
+class Value;
+}  // namespace Json
+
+class nsProfiler final : public nsIProfiler {
+ public:
+  nsProfiler();
+
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIPROFILER
+
+  nsresult Init();
+
+  static nsProfiler* GetOrCreate() {
+    nsCOMPtr<nsIProfiler> iprofiler =
+        do_GetService("@mozilla.org/tools/profiler;1");
+    return static_cast<nsProfiler*>(iprofiler.get());
+  }
+
+ private:
+  ~nsProfiler();
+
+  using GatheringPromiseAndroid =
+      mozilla::MozPromise<FallibleTArray<uint8_t>, nsresult, true>;
+  using GatheringPromise =
+      mozilla::MozPromise<mozilla::ProfileAndAdditionalInformation, nsresult,
+                          false>;
+  using SymbolTablePromise =
+      mozilla::MozPromise<mozilla::SymbolTable, nsresult, true>;
+
+  RefPtr<GatheringPromise> StartGathering(double aSinceTime);
+  void GatheredOOPProfile(
+      base::ProcessId aChildPid, const nsACString& aProfile,
+      mozilla::Maybe<mozilla::ProfileGenerationAdditionalInformation>&&
+          aAdditionalInformation);
+  void FinishGathering();
+  void ResetGathering(nsresult aPromiseRejectionIfPending);
+  static void GatheringTimerCallback(nsITimer* aTimer, void* aClosure);
+  void RestartGatheringTimer();
+
+  RefPtr<SymbolTablePromise> GetSymbolTableMozPromise(
+      const nsACString& aDebugPath, const nsACString& aBreakpadID);
+
+  struct ExitProfile {
+    nsCString mJSON;
+    uint64_t mBufferPositionAtGatherTime;
+  };
+
+  struct PendingProfile {
+    base::ProcessId childPid;
+
+    mozilla::ProportionValue progressProportion;
+    nsCString progressLocation;
+
+    mozilla::TimeStamp lastProgressRequest;
+    mozilla::TimeStamp lastProgressResponse;
+    mozilla::TimeStamp lastProgressChange;
+
+    explicit PendingProfile(base::ProcessId aChildPid) : childPid(aChildPid) {}
+  };
+
+  PendingProfile* GetPendingProfile(base::ProcessId aChildPid);
+  // Returns false if the request could not be sent.
+  bool SendProgressRequest(PendingProfile& aPendingProfile);
+
+  // If the log is active, call aJsonLogObjectUpdater(Json::Value&) on the log's
+  // root object.
+  template <typename JsonLogObjectUpdater>
+  void Log(JsonLogObjectUpdater&& aJsonLogObjectUpdater);
+  // If the log is active, call aJsonArrayAppender(Json::Value&) on a Json
+  // array that already contains a timestamp, and to which event-related
+  // elements may be appended.
+  template <typename JsonArrayAppender>
+  void LogEvent(JsonArrayAppender&& aJsonArrayAppender);
+  void LogEventLiteralString(const char* aEventString);
+
+  // These fields are all related to profile gathering.
+  mozilla::Vector<ExitProfile> mExitProfiles;
+  mozilla::Maybe<mozilla::MozPromiseHolder<GatheringPromise>> mPromiseHolder;
+  nsCOMPtr<nsIThread> mSymbolTableThread;
+  mozilla::Maybe<mozilla::FailureLatchSource> mFailureLatchSource;
+  mozilla::Maybe<SpliceableChunkedJSONWriter> mWriter;
+  mozilla::Maybe<mozilla::ProfileGenerationAdditionalInformation>
+      mProfileGenerationAdditionalInformation;
+  mozilla::Vector<PendingProfile> mPendingProfiles;
+  bool mGathering;
+  nsCOMPtr<nsITimer> mGatheringTimer;
+  // Supplemental log to the profiler's "profilingLog" (which has already been
+  // completed in JSON profiles that are gathered).
+  mozilla::UniquePtr<Json::Value> mGatheringLog;
+};
+
+#endif  // nsProfiler_h
diff --git a/tools/profiler/gecko/nsProfilerCIID.h b/tools/profiler/gecko/nsProfilerCIID.h
new file mode 100644
index 0000000000..3df44596b1
--- /dev/null
+++ b/tools/profiler/gecko/nsProfilerCIID.h
@@ -0,0 +1,16 @@
+/* -*- Mode: C++; tab-width: 2; 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/. */
+
+#ifndef nsProfilerCIID_h__
+#define nsProfilerCIID_h__
+
+#define NS_PROFILER_CID                              \
+  {                                                  \
+    0x25db9b8e, 0x8123, 0x4de1, {                    \
+      0xb6, 0x6d, 0x8b, 0xbb, 0xed, 0xf2, 0xcd, 0xf4 \
+    }                                                \
+  }
+
+#endif
diff --git a/tools/profiler/gecko/nsProfilerStartParams.cpp b/tools/profiler/gecko/nsProfilerStartParams.cpp
new file mode 100644
index 0000000000..dd7c3f4ab7
--- /dev/null
+++ b/tools/profiler/gecko/nsProfilerStartParams.cpp
@@ -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 "nsProfilerStartParams.h"
+#include "ipc/IPCMessageUtils.h"
+
+NS_IMPL_ISUPPORTS(nsProfilerStartParams, nsIProfilerStartParams)
+
+nsProfilerStartParams::nsProfilerStartParams(
+    uint32_t aEntries, const mozilla::Maybe<double>& aDuration,
+    double aInterval, uint32_t aFeatures, nsTArray<nsCString>&& aFilters,
+    uint64_t aActiveTabID)
+    : mEntries(aEntries),
+      mDuration(aDuration),
+      mInterval(aInterval),
+      mFeatures(aFeatures),
+      mFilters(std::move(aFilters)),
+      mActiveTabID(aActiveTabID) {}
+
+nsProfilerStartParams::~nsProfilerStartParams() {}
+
+NS_IMETHODIMP
+nsProfilerStartParams::GetEntries(uint32_t* aEntries) {
+  NS_ENSURE_ARG_POINTER(aEntries);
+  *aEntries = mEntries;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfilerStartParams::GetDuration(double* aDuration) {
+  NS_ENSURE_ARG_POINTER(aDuration);
+  if (mDuration) {
+    *aDuration = *mDuration;
+  } else {
+    *aDuration = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfilerStartParams::GetInterval(double* aInterval) {
+  NS_ENSURE_ARG_POINTER(aInterval);
+  *aInterval = mInterval;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsProfilerStartParams::GetFeatures(uint32_t* aFeatures) {
+  NS_ENSURE_ARG_POINTER(aFeatures);
+  *aFeatures = mFeatures;
+  return NS_OK;
+}
+
+const nsTArray<nsCString>& nsProfilerStartParams::GetFilters() {
+  return mFilters;
+}
+
+NS_IMETHODIMP
+nsProfilerStartParams::GetActiveTabID(uint64_t* aActiveTabID) {
+  NS_ENSURE_ARG_POINTER(aActiveTabID);
+  *aActiveTabID = mActiveTabID;
+  return NS_OK;
+}
diff --git a/tools/profiler/gecko/nsProfilerStartParams.h b/tools/profiler/gecko/nsProfilerStartParams.h
new file mode 100644
index 0000000000..25c2b5082f
--- /dev/null
+++ b/tools/profiler/gecko/nsProfilerStartParams.h
@@ -0,0 +1,36 @@
+/* -*- 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/. */
+
+#ifndef _NSPROFILERSTARTPARAMS_H_
+#define _NSPROFILERSTARTPARAMS_H_
+
+#include "nsIProfiler.h"
+#include "nsString.h"
+#include "nsTArray.h"
+
+class nsProfilerStartParams : public nsIProfilerStartParams {
+ public:
+  // This class can be used on multiple threads. For example, it's used for the
+  // observer notification from profiler_start, which can run on any thread but
+  // posts the notification to the main thread.
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIPROFILERSTARTPARAMS
+
+  nsProfilerStartParams(uint32_t aEntries,
+                        const mozilla::Maybe<double>& aDuration,
+                        double aInterval, uint32_t aFeatures,
+                        nsTArray<nsCString>&& aFilters, uint64_t aActiveTabID);
+
+ private:
+  virtual ~nsProfilerStartParams();
+  uint32_t mEntries;
+  mozilla::Maybe<double> mDuration;
+  double mInterval;
+  uint32_t mFeatures;
+  nsTArray<nsCString> mFilters;
+  uint64_t mActiveTabID;
+};
+
+#endif