Improve performance of dragged tab renderering....

chrome/browser/renderer_host/backing_store.h

Index: chrome/browser/renderer_host/backing_store.h
===================================================================
--- chrome/browser/renderer_host/backing_store.h	(revision 20318)
+++ chrome/browser/renderer_host/backing_store.h	(working copy)
@@ -23,6 +23,7 @@
 class RenderWidgetHost;
 class SkBitmap;
 class TransportDIB;
+typedef struct _GdkDrawable GdkDrawable;
 
 // BackingStore ----------------------------------------------------------------
 
@@ -75,6 +76,11 @@
   SkBitmap PaintRectToBitmap(const gfx::Rect& rect);
 #endif
 
+#if defined(TOOLKIT_GTK)
+  // Paint the backing store into the target's |dest_rect|.
+  void PaintToRect(const gfx::Rect& dest_rect, GdkDrawable* target);
+#endif
+
   // Paints the bitmap from the renderer onto the backing store.
   void PaintRect(base::ProcessHandle process,
                  TransportDIB* bitmap,