diff -r 000000000000 -r 6474c204b198 gfx/layers/ipc/CompositorChild.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/ipc/CompositorChild.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,122 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_CompositorChild_h
+#define mozilla_layers_CompositorChild_h
+
+#include "base/basictypes.h"            // for DISALLOW_EVIL_CONSTRUCTORS
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT_HELPER2
+#include "mozilla/Attributes.h"         // for MOZ_OVERRIDE
+#include "mozilla/ipc/ProtocolUtils.h"
+#include "mozilla/layers/PCompositorChild.h"
+#include "nsAutoPtr.h"                  // for nsRefPtr
+#include "nsClassHashtable.h"           // for nsClassHashtable
+#include "nsCOMPtr.h"                   // for nsCOMPtr
+#include "nsHashKeys.h"                 // for nsUint64HashKey
+#include "nsISupportsImpl.h"            // for NS_INLINE_DECL_REFCOUNTING
+
+class nsIObserver;
+
+namespace mozilla {
+namespace layers {
+
+class ClientLayerManager;
+class CompositorParent;
+class FrameMetrics;
+
+class CompositorChild MOZ_FINAL : public PCompositorChild
+{
+  NS_INLINE_DECL_REFCOUNTING(CompositorChild)
+public:
+  CompositorChild(ClientLayerManager *aLayerManager);
+
+  void Destroy();
+
+  /**
+   * Lookup the FrameMetrics shared by the compositor process with the
+   * associated FrameMetrics::ViewID. The returned FrameMetrics is used
+   * in progressive paint calculations.
+   */
+  bool LookupCompositorFrameMetrics(const FrameMetrics::ViewID aId, FrameMetrics&);
+
+  /**
+   * We're asked to create a new Compositor in response to an Opens()
+   * or Bridge() request from our parent process.  The Transport is to
+   * the compositor's context.
+   */
+  static PCompositorChild*
+  Create(Transport* aTransport, ProcessId aOtherProcess);
+
+  static CompositorChild* Get();
+
+  static bool ChildProcessHasCompositor() { return sCompositor != nullptr; }
+
+  virtual bool RecvInvalidateAll() MOZ_OVERRIDE;
+
+  virtual bool RecvDidComposite(const uint64_t& aId) MOZ_OVERRIDE;
+
+private:
+  // Private destructor, to discourage deletion outside of Release():
+  virtual ~CompositorChild();
+
+  virtual PLayerTransactionChild*
+    AllocPLayerTransactionChild(const nsTArray<LayersBackend>& aBackendHints,
+                                const uint64_t& aId,
+                                TextureFactoryIdentifier* aTextureFactoryIdentifier,
+                                bool* aSuccess) MOZ_OVERRIDE;
+
+  virtual bool DeallocPLayerTransactionChild(PLayerTransactionChild *aChild) MOZ_OVERRIDE;
+
+  virtual void ActorDestroy(ActorDestroyReason aWhy) MOZ_OVERRIDE;
+
+  virtual bool RecvSharedCompositorFrameMetrics(const mozilla::ipc::SharedMemoryBasic::Handle& metrics,
+                                                const CrossProcessMutexHandle& handle,
+                                                const uint32_t& aAPZCId) MOZ_OVERRIDE;
+
+  virtual bool RecvReleaseSharedCompositorFrameMetrics(const ViewID& aId,
+                                                       const uint32_t& aAPZCId) MOZ_OVERRIDE;
+
+  // Class used to store the shared FrameMetrics, mutex, and APZCId  in a hash table
+  class SharedFrameMetricsData {
+  public:
+    SharedFrameMetricsData(
+        const mozilla::ipc::SharedMemoryBasic::Handle& metrics,
+        const CrossProcessMutexHandle& handle,
+        const uint32_t& aAPZCId);
+
+    ~SharedFrameMetricsData();
+
+    void CopyFrameMetrics(FrameMetrics* aFrame);
+    FrameMetrics::ViewID GetViewID();
+    uint32_t GetAPZCId();
+
+  private:
+    // Pointer to the class that allows access to the shared memory that contains
+    // the shared FrameMetrics
+    mozilla::ipc::SharedMemoryBasic* mBuffer;
+    CrossProcessMutex* mMutex;
+    // Unique ID of the APZC that is sharing the FrameMetrics
+    uint32_t mAPZCId;
+  };
+
+  nsRefPtr<ClientLayerManager> mLayerManager;
+
+  // The ViewID of the FrameMetrics is used as the key for this hash table.
+  // While this should be safe to use since the ViewID is unique
+  nsClassHashtable<nsUint64HashKey, SharedFrameMetricsData> mFrameMetricsTable;
+
+  // When we're in a child process, this is the process-global
+  // compositor that we use to forward transactions directly to the
+  // compositor context in another process.
+  static CompositorChild* sCompositor;
+
+  DISALLOW_EVIL_CONSTRUCTORS(CompositorChild);
+};
+
+} // layers
+} // mozilla
+
+#endif // mozilla_layers_CompositorChild_h