Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

content/browser/renderer_host/render_widget_host_impl.h

Index: content/browser/renderer_host/render_widget_host_impl.h
diff --git a/content/browser/renderer_host/render_widget_host_impl.h b/content/browser/renderer_host/render_widget_host_impl.h
index 9485aa8828ef69db3d986761f7a237dbcc8dea42..82cd11ef5f30216fb8c27dcd8553ad2defb5eb5f 100644
--- a/content/browser/renderer_host/render_widget_host_impl.h
+++ b/content/browser/renderer_host/render_widget_host_impl.h
@@ -10,6 +10,7 @@
 #include <map>
 #include <queue>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "base/callback.h"
@@ -450,6 +451,14 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   // suppress_next_char_events_.
   void SuppressNextCharEvents();
 
+  // Grab snapshot from renderer side. This is used when CopyFromBackingStore
+  // fails due to the backing store not being available or, in composited mode,
+  // when the accelerated surface is not available to the browser side.
+  void GetSnapshotFromRenderer(
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,
+      const base::Callback<void(bool, const SkBitmap&)>& callback);
+
  protected:
   virtual RenderWidgetHostImpl* AsRenderWidgetHostImpl() OVERRIDE;
 
@@ -602,6 +611,7 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   void OnWindowlessPluginDummyWindowDestroyed(
       gfx::NativeViewId dummy_activation_window);
 #endif
+  void OnSnapshot(bool success, const SkBitmap& bitmap);
 
   // Called (either immediately or asynchronously) after we're done with our
   // BackingStore and can send an ACK to the renderer so it can paint onto it
@@ -857,6 +867,10 @@ class CONTENT_EXPORT RenderWidgetHostImpl : virtual public RenderWidgetHost,
   scoped_ptr<GestureEventFilter> gesture_event_filter_;
   scoped_ptr<OverscrollController> overscroll_controller_;
 
+  typedef std::pair<gfx::Size, base::Callback<void(bool, const SkBitmap&)> >
+      PendingSnapshotInfo;
+  std::queue<PendingSnapshotInfo> pending_snapshots_;
+
 #if defined(OS_WIN)
   std::list<HWND> dummy_windows_for_activation_;
 #endif