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

content/public/browser/render_widget_host.h

Index: content/public/browser/render_widget_host.h
diff --git a/content/public/browser/render_widget_host.h b/content/public/browser/render_widget_host.h
index 113477a4a2cf000f57e63292b1ccac7c476dea85..008d88a5e6c655d35e7a1327bd3e1b0f492e8071 100644
--- a/content/public/browser/render_widget_host.h
+++ b/content/public/browser/render_widget_host.h
@@ -284,6 +284,16 @@ class CONTENT_EXPORT RenderWidgetHost : public IPC::Sender {
   // Get the screen info corresponding to this render widget.
   virtual void GetWebScreenInfo(WebKit::WebScreenInfo* result) = 0;
 
+  // Grabs snapshot from renderer side, resizes it to |dst_size| and returns the
+  // bitmap to a callback. This is an expensive operation due to
+  // the IPC, but can be used when CopyFromBackingStore due to the backing store
+  // not being available or, in composited mode, when the accelerated surface is
+  // not available to the browser side.
+  virtual void GetSnapshotFromRenderer(
+      const gfx::Rect& src_subrect,
+      const gfx::Size& dst_size,
+      const base::Callback<void(bool, const SkBitmap&)>& callback) = 0;
+
  protected:
   friend class RenderWidgetHostImpl;