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diff --git a/gfx/layers/ipc/ImageBridgeChild.h b/gfx/layers/ipc/ImageBridgeChild.h
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+++ b/gfx/layers/ipc/ImageBridgeChild.h
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+/* -*- 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 MOZILLA_GFX_IMAGEBRIDGECHILD_H
+#define MOZILLA_GFX_IMAGEBRIDGECHILD_H
+
+#include <stddef.h>                     // for size_t
+#include <stdint.h>                     // for uint32_t, uint64_t
+#include "mozilla/Attributes.h"         // for override
+#include "mozilla/Atomics.h"
+#include "mozilla/RefPtr.h"             // for already_AddRefed
+#include "mozilla/ipc/SharedMemory.h"   // for SharedMemory, etc
+#include "mozilla/layers/CanvasClient.h"
+#include "mozilla/layers/CompositableForwarder.h"
+#include "mozilla/layers/CompositorTypes.h"
+#include "mozilla/layers/PImageBridgeChild.h"
+#include "mozilla/Mutex.h"
+#include "nsDebug.h"                    // for NS_RUNTIMEABORT
+#include "nsIObserver.h"
+#include "nsRegion.h"                   // for nsIntRegion
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/ReentrantMonitor.h"   // for ReentrantMonitor, etc
+
+class MessageLoop;
+
+namespace base {
+class Thread;
+} // namespace base
+
+namespace mozilla {
+namespace ipc {
+class Shmem;
+} // namespace ipc
+
+namespace layers {
+
+class AsyncCanvasRenderer;
+class ImageClient;
+class ImageContainer;
+class ImageContainerChild;
+class ImageBridgeParent;
+class CompositableClient;
+struct CompositableTransaction;
+class Image;
+class TextureClient;
+class SynchronousTask;
+struct AllocShmemParams;
+
+/**
+ * Returns true if the current thread is the ImageBrdigeChild's thread.
+ *
+ * Can be called from any thread.
+ */
+bool InImageBridgeChildThread();
+
+/**
+ * The ImageBridge protocol is meant to allow ImageContainers to forward images
+ * directly to the compositor thread/process without using the main thread.
+ *
+ * ImageBridgeChild is a CompositableForwarder just like ShadowLayerForwarder.
+ * This means it also does transactions with the compositor thread/process,
+ * except that the transactions are restricted to operations on the Compositables
+ * and cannot contain messages affecting layers directly.
+ *
+ * ImageBridgeChild is also a ISurfaceAllocator. It can be used to allocate or
+ * deallocate data that is shared with the compositor. The main differerence
+ * with other ISurfaceAllocators is that some of its overriden methods can be
+ * invoked from any thread.
+ *
+ * There are three important phases in the ImageBridge protocol. These three steps
+ * can do different things depending if (A) the ImageContainer uses ImageBridge
+ * or (B) it does not use ImageBridge:
+ *
+ * - When an ImageContainer calls its method SetCurrentImage:
+ *   - (A) The image is sent directly to the compositor process through the
+ *   ImageBridge IPDL protocol.
+ *   On the compositor side the image is stored in a global table that associates
+ *   the image with an ID corresponding to the ImageContainer, and a composition is
+ *   triggered.
+ *   - (B) Since it does not have an ImageBridge, the image is not sent yet.
+ *   instead the will be sent to the compositor during the next layer transaction
+ *   (on the main thread).
+ *
+ * - During a Layer transaction:
+ *   - (A) The ImageContainer uses ImageBridge. The image is already available to the
+ *   compositor process because it has been sent with SetCurrentImage. Yet, the
+ *   CompositableHost on the compositor side will needs the ID referring to the
+ *   ImageContainer to access the Image. So during the Swap operation that happens
+ *   in the transaction, we swap the container ID rather than the image data.
+ *   - (B) Since the ImageContainer does not use ImageBridge, the image data is swaped.
+ *
+ * - During composition:
+ *   - (A) The CompositableHost has an AsyncID, it looks up the ID in the 
+ *   global table to see if there is an image. If there is no image, nothing is rendered.
+ *   - (B) The CompositableHost has image data rather than an ID (meaning it is not
+ *   using ImageBridge), then it just composites the image data normally.
+ *
+ * This means that there might be a possibility for the ImageBridge to send the first
+ * frame before the first layer transaction that will pass the container ID to the
+ * CompositableHost happens. In this (unlikely) case the layer is not composited
+ * until the layer transaction happens. This means this scenario is not harmful.
+ *
+ * Since sending an image through imageBridge triggers compositing, the main thread is
+ * not used at all (except for the very first transaction that provides the
+ * CompositableHost with an AsyncID).
+ */
+class ImageBridgeChild final : public PImageBridgeChild
+                             , public CompositableForwarder
+                             , public TextureForwarder
+{
+  friend class ImageContainer;
+
+  typedef InfallibleTArray<AsyncParentMessageData> AsyncParentMessageArray;
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(ImageBridgeChild, override);
+
+  TextureForwarder* GetTextureForwarder() override { return this; }
+  LayersIPCActor* GetLayersIPCActor() override { return this; }
+
+  /**
+   * Creates the image bridge with a dedicated thread for ImageBridgeChild.
+   *
+   * We may want to use a specifi thread in the future. In this case, use
+   * CreateWithThread instead.
+   */
+  static void InitSameProcess();
+
+  static void InitWithGPUProcess(Endpoint<PImageBridgeChild>&& aEndpoint);
+  static bool InitForContent(Endpoint<PImageBridgeChild>&& aEndpoint);
+  static bool ReinitForContent(Endpoint<PImageBridgeChild>&& aEndpoint);
+
+  /**
+   * Destroys the image bridge by calling DestroyBridge, and destroys the
+   * ImageBridge's thread.
+   *
+   * If you don't want to destroy the thread, call DestroyBridge directly
+   * instead.
+   */
+  static void ShutDown();
+
+  /**
+   * returns the singleton instance.
+   *
+   * can be called from any thread.
+   */
+  static RefPtr<ImageBridgeChild> GetSingleton();
+
+
+  static void IdentifyCompositorTextureHost(const TextureFactoryIdentifier& aIdentifier);
+
+  void BeginTransaction();
+  void EndTransaction();
+
+  /**
+   * Returns the ImageBridgeChild's thread.
+   *
+   * Can be called from any thread.
+   */
+  base::Thread * GetThread() const;
+
+  /**
+   * Returns the ImageBridgeChild's message loop.
+   *
+   * Can be called from any thread.
+   */
+  virtual MessageLoop * GetMessageLoop() const override;
+
+  virtual base::ProcessId GetParentPid() const override { return OtherPid(); }
+
+  PCompositableChild* AllocPCompositableChild(const TextureInfo& aInfo,
+                                              PImageContainerChild* aChild, uint64_t* aID) override;
+  bool DeallocPCompositableChild(PCompositableChild* aActor) override;
+
+  virtual PTextureChild*
+  AllocPTextureChild(const SurfaceDescriptor& aSharedData, const LayersBackend& aLayersBackend, const TextureFlags& aFlags, const uint64_t& aSerial) override;
+
+  virtual bool
+  DeallocPTextureChild(PTextureChild* actor) override;
+
+  PMediaSystemResourceManagerChild*
+  AllocPMediaSystemResourceManagerChild() override;
+  bool
+  DeallocPMediaSystemResourceManagerChild(PMediaSystemResourceManagerChild* aActor) override;
+
+  virtual PImageContainerChild*
+  AllocPImageContainerChild() override;
+  virtual bool
+  DeallocPImageContainerChild(PImageContainerChild* actor) override;
+
+  virtual bool
+  RecvParentAsyncMessages(InfallibleTArray<AsyncParentMessageData>&& aMessages) override;
+
+  virtual bool
+  RecvDidComposite(InfallibleTArray<ImageCompositeNotification>&& aNotifications) override;
+
+  // Create an ImageClient from any thread.
+  RefPtr<ImageClient> CreateImageClient(
+    CompositableType aType,
+    ImageContainer* aImageContainer,
+    ImageContainerChild* aContainerChild);
+
+  // Create an ImageClient from the ImageBridge thread.
+  RefPtr<ImageClient> CreateImageClientNow(
+    CompositableType aType,
+    ImageContainer* aImageContainer,
+    ImageContainerChild* aContainerChild);
+
+  already_AddRefed<CanvasClient> CreateCanvasClient(CanvasClient::CanvasClientType aType,
+                                                    TextureFlags aFlag);
+  void ReleaseImageContainer(RefPtr<ImageContainerChild> aChild);
+  void UpdateAsyncCanvasRenderer(AsyncCanvasRenderer* aClient);
+  void UpdateImageClient(RefPtr<ImageClient> aClient, RefPtr<ImageContainer> aContainer);
+  static void DispatchReleaseTextureClient(TextureClient* aClient);
+
+  /**
+   * Flush all Images sent to CompositableHost.
+   */
+  void FlushAllImages(ImageClient* aClient, ImageContainer* aContainer);
+
+  virtual bool IPCOpen() const override { return mCanSend; }
+
+private:
+
+  /**
+   * This must be called by the static function DeleteImageBridgeSync defined
+   * in ImageBridgeChild.cpp ONLY.
+   */
+  ~ImageBridgeChild();
+
+  // Helpers for dispatching.
+  already_AddRefed<CanvasClient> CreateCanvasClientNow(
+    CanvasClient::CanvasClientType aType,
+    TextureFlags aFlags);
+  void CreateCanvasClientSync(
+    SynchronousTask* aTask,
+    CanvasClient::CanvasClientType aType,
+    TextureFlags aFlags,
+    RefPtr<CanvasClient>* const outResult);
+
+  void CreateImageClientSync(
+    SynchronousTask* aTask,
+    RefPtr<ImageClient>* result,
+    CompositableType aType,
+    ImageContainer* aImageContainer,
+    ImageContainerChild* aContainerChild);
+
+  void ReleaseTextureClientNow(TextureClient* aClient);
+
+  void UpdateAsyncCanvasRendererNow(AsyncCanvasRenderer* aClient);
+  void UpdateAsyncCanvasRendererSync(
+    SynchronousTask* aTask,
+    AsyncCanvasRenderer* aWrapper);
+
+  void FlushAllImagesSync(
+    SynchronousTask* aTask,
+    ImageClient* aClient,
+    ImageContainer* aContainer);
+
+  void ProxyAllocShmemNow(SynchronousTask* aTask, AllocShmemParams* aParams);
+  void ProxyDeallocShmemNow(SynchronousTask* aTask, Shmem* aShmem, bool* aResult);
+
+public:
+  // CompositableForwarder
+
+  virtual void Connect(CompositableClient* aCompositable,
+                       ImageContainer* aImageContainer) override;
+
+  virtual bool UsesImageBridge() const override { return true; }
+
+  /**
+   * See CompositableForwarder::UseTextures
+   */
+  virtual void UseTextures(CompositableClient* aCompositable,
+                           const nsTArray<TimedTextureClient>& aTextures) override;
+  virtual void UseComponentAlphaTextures(CompositableClient* aCompositable,
+                                         TextureClient* aClientOnBlack,
+                                         TextureClient* aClientOnWhite) override;
+
+  void Destroy(CompositableChild* aCompositable) override;
+
+  /**
+   * Hold TextureClient ref until end of usage on host side if TextureFlags::RECYCLE is set.
+   * Host side's usage is checked via CompositableRef.
+   */
+  void HoldUntilCompositableRefReleasedIfNecessary(TextureClient* aClient);
+
+  /**
+   * Notify id of Texture When host side end its use. Transaction id is used to
+   * make sure if there is no newer usage.
+   */
+  void NotifyNotUsed(uint64_t aTextureId, uint64_t aFwdTransactionId);
+
+  virtual void CancelWaitForRecycle(uint64_t aTextureId) override;
+
+  virtual bool DestroyInTransaction(PTextureChild* aTexture, bool synchronously) override;
+  virtual bool DestroyInTransaction(PCompositableChild* aCompositable, bool synchronously) override;
+
+  virtual void RemoveTextureFromCompositable(CompositableClient* aCompositable,
+                                             TextureClient* aTexture) override;
+
+  virtual void UseTiledLayerBuffer(CompositableClient* aCompositable,
+                                   const SurfaceDescriptorTiles& aTileLayerDescriptor) override
+  {
+    NS_RUNTIMEABORT("should not be called");
+  }
+
+  virtual void UpdateTextureRegion(CompositableClient* aCompositable,
+                                   const ThebesBufferData& aThebesBufferData,
+                                   const nsIntRegion& aUpdatedRegion) override {
+    NS_RUNTIMEABORT("should not be called");
+  }
+
+  // ISurfaceAllocator
+
+  /**
+   * See ISurfaceAllocator.h
+   * Can be used from any thread.
+   * If used outside the ImageBridgeChild thread, it will proxy a synchronous
+   * call on the ImageBridgeChild thread.
+   */
+  virtual bool AllocUnsafeShmem(size_t aSize,
+                                mozilla::ipc::SharedMemory::SharedMemoryType aShmType,
+                                mozilla::ipc::Shmem* aShmem) override;
+  virtual bool AllocShmem(size_t aSize,
+                          mozilla::ipc::SharedMemory::SharedMemoryType aShmType,
+                          mozilla::ipc::Shmem* aShmem) override;
+
+  /**
+   * See ISurfaceAllocator.h
+   * Can be used from any thread.
+   * If used outside the ImageBridgeChild thread, it will proxy a synchronous
+   * call on the ImageBridgeChild thread.
+   */
+  virtual bool DeallocShmem(mozilla::ipc::Shmem& aShmem) override;
+
+  virtual PTextureChild* CreateTexture(const SurfaceDescriptor& aSharedData,
+                                       LayersBackend aLayersBackend,
+                                       TextureFlags aFlags,
+                                       uint64_t aSerial) override;
+
+  virtual bool IsSameProcess() const override;
+
+  virtual void UpdateFwdTransactionId() override { ++mFwdTransactionId; }
+  virtual uint64_t GetFwdTransactionId() override { return mFwdTransactionId; }
+
+  bool InForwarderThread() override {
+    return InImageBridgeChildThread();
+  }
+
+  virtual void HandleFatalError(const char* aName, const char* aMsg) const override;
+
+protected:
+  ImageBridgeChild();
+  bool DispatchAllocShmemInternal(size_t aSize,
+                                  SharedMemory::SharedMemoryType aType,
+                                  Shmem* aShmem,
+                                  bool aUnsafe);
+
+  void Bind(Endpoint<PImageBridgeChild>&& aEndpoint);
+  void BindSameProcess(RefPtr<ImageBridgeParent> aParent);
+
+  void SendImageBridgeThreadId();
+
+  void WillShutdown();
+  void ShutdownStep1(SynchronousTask* aTask);
+  void ShutdownStep2(SynchronousTask* aTask);
+  void MarkShutDown();
+
+  void ActorDestroy(ActorDestroyReason aWhy) override;
+  void DeallocPImageBridgeChild() override;
+
+  bool CanSend() const;
+
+  static void ShutdownSingleton();
+
+private:
+  CompositableTransaction* mTxn;
+
+  bool mCanSend;
+  bool mCalledClose;
+
+  /**
+   * Transaction id of CompositableForwarder.
+   * It is incrementaed by UpdateFwdTransactionId() in each BeginTransaction() call.
+   */
+  uint64_t mFwdTransactionId;
+
+  /**
+   * Hold TextureClients refs until end of their usages on host side.
+   * It defer calling of TextureClient recycle callback.
+   */
+  nsDataHashtable<nsUint64HashKey, RefPtr<TextureClient> > mTexturesWaitingRecycled;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif