diff -r 000000000000 -r 6474c204b198 gfx/layers/client/CanvasClient.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/layers/client/CanvasClient.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,138 @@
+/* -*- 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_CANVASCLIENT_H
+#define MOZILLA_GFX_CANVASCLIENT_H
+
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT, etc
+#include "mozilla/Attributes.h"         // for MOZ_OVERRIDE
+#include "mozilla/RefPtr.h"             // for RefPtr, TemporaryRef
+#include "mozilla/layers/CompositableClient.h"  // for CompositableClient
+#include "mozilla/layers/CompositorTypes.h"  // for TextureInfo, etc
+#include "mozilla/layers/LayersSurfaces.h"  // for SurfaceDescriptor
+#include "mozilla/layers/TextureClient.h"  // for TextureClient, etc
+#include "mozilla/mozalloc.h"           // for operator delete
+
+#include "mozilla/gfx/Point.h"          // for IntSize
+#include "mozilla/gfx/Types.h"          // for SurfaceFormat
+
+namespace mozilla {
+namespace gfx {
+class SharedSurface;
+}
+}
+
+namespace mozilla {
+namespace layers {
+
+class ClientCanvasLayer;
+class CompositableForwarder;
+
+/**
+ * Compositable client for 2d and webgl canvas.
+ */
+class CanvasClient : public CompositableClient
+{
+public:
+  /**
+   * Creates, configures, and returns a new canvas client. If necessary, a
+   * message will be sent to the compositor to create a corresponding image
+   * host.
+   */
+  enum CanvasClientType {
+    CanvasClientSurface,
+    CanvasClientGLContext,
+  };
+  static TemporaryRef<CanvasClient> CreateCanvasClient(CanvasClientType aType,
+                                                       CompositableForwarder* aFwd,
+                                                       TextureFlags aFlags);
+
+  CanvasClient(CompositableForwarder* aFwd, TextureFlags aFlags)
+    : CompositableClient(aFwd, aFlags)
+  {
+    mTextureInfo.mTextureFlags = aFlags;
+  }
+
+  virtual ~CanvasClient() {}
+
+  virtual void Clear() {};
+
+  virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) = 0;
+
+  virtual void Updated() { }
+
+protected:
+  TextureInfo mTextureInfo;
+};
+
+// Used for 2D canvases and WebGL canvas on non-GL systems where readback is requried.
+class CanvasClient2D : public CanvasClient
+{
+public:
+  CanvasClient2D(CompositableForwarder* aLayerForwarder,
+                 TextureFlags aFlags)
+    : CanvasClient(aLayerForwarder, aFlags)
+  {
+  }
+
+  TextureInfo GetTextureInfo() const
+  {
+    return TextureInfo(COMPOSITABLE_IMAGE);
+  }
+
+  virtual void Clear() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
+  virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) MOZ_OVERRIDE;
+
+  virtual bool AddTextureClient(TextureClient* aTexture) MOZ_OVERRIDE
+  {
+    MOZ_ASSERT((mTextureInfo.mTextureFlags & aTexture->GetFlags()) == mTextureInfo.mTextureFlags);
+    return CompositableClient::AddTextureClient(aTexture);
+  }
+
+  virtual void OnDetach() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
+private:
+  RefPtr<TextureClient> mBuffer;
+};
+
+// Used for GL canvases where we don't need to do any readback, i.e., with a
+// GL backend.
+class CanvasClientSurfaceStream : public CanvasClient
+{
+public:
+  CanvasClientSurfaceStream(CompositableForwarder* aLayerForwarder, TextureFlags aFlags);
+
+  TextureInfo GetTextureInfo() const
+  {
+    return TextureInfo(COMPOSITABLE_IMAGE);
+  }
+
+  virtual void Clear() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
+  virtual void Update(gfx::IntSize aSize, ClientCanvasLayer* aLayer) MOZ_OVERRIDE;
+
+  virtual void OnDetach() MOZ_OVERRIDE
+  {
+    mBuffer = nullptr;
+  }
+
+private:
+  RefPtr<TextureClient> mBuffer;
+};
+
+}
+}
+
+#endif