Provide shared context to Platform API in renderer.

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index f609bdb0effdbeac9aae95b2aaba722044790bce..efa587e3aa1b1550cedabaf1790207c7e08b6ba9 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -17,6 +17,7 @@
 #include "content/common/child_thread.h"
 #include "content/common/content_export.h"
 #include "content/common/gpu/client/gpu_channel_host.h"
+#include "content/common/gpu/client/offscreen_context.h"
 #include "content/common/gpu/gpu_process_launch_causes.h"
 #include "content/public/renderer/render_thread.h"
 #include "ipc/ipc_channel_proxy.h"
@@ -84,9 +85,11 @@ class WebGraphicsContext3DCommandBufferImpl;
 // Most of the communication occurs in the form of IPC messages.  They are
 // routed to the RenderThread according to the routing IDs of the messages.
 // The routing IDs correspond to RenderView instances.
-class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
-                                        public ChildThread,
-                                        public GpuChannelHostFactory {
+class CONTENT_EXPORT RenderThreadImpl
+    : public RenderThread,
+      public ChildThread,
+      public GpuChannelHostFactory,
+      public OffscreenContextClient {
  public:
   static RenderThreadImpl* current();
 
@@ -198,7 +201,10 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
     return audio_message_filter_.get();
   }
 
-
+  WebKit::WebGraphicsContext3D* OffscreenContext3dForMainThread();
+  WebKit::WebGraphicsContext3D* OffscreenContext3dForCompositorThread();
+  GrContext* OffscreenGrContextForMainThread();
+  GrContext* OffscreenGrContextForCompositorThread();
 
   // Creates the embedder implementation of WebMediaStreamCenter.
   // The resulting object is owned by WebKit and deleted by WebKit at tear-down.
@@ -323,6 +329,14 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
 
   void IdleHandlerInForegroundTab();
 
+  // OffscreenContextClient implementation.
+  virtual WebKit::WebGraphicsContext3D* CreateOffscreenContext()
+      OVERRIDE;
+  virtual void DidLoseContext(OffscreenContext* offscreen_context)
+      OVERRIDE {}
+  virtual void DidCreateContext(OffscreenContext* offscreen_context,
+                                bool success) OVERRIDE {}
+
   // These objects live solely on the render thread.
   scoped_ptr<AppCacheDispatcher> appcache_dispatcher_;
   scoped_ptr<DomStorageDispatcher> dom_storage_dispatcher_;
@@ -386,6 +400,9 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
   scoped_ptr<CompositorThread> compositor_thread_;
   scoped_refptr<IPC::ForwardingMessageFilter> compositor_output_surface_filter_;
 
+  OffscreenContext shared_context_main_thread_;
+  OffscreenContext shared_context_compositor_thread_;
+
   ObserverList<RenderProcessObserver> observers_;
 
   class GpuVDAContextLostCallback;