Get windowless plugins working when accelerated compositing is turned on.

content/renderer/webplugin_delegate_proxy.h

Index: content/renderer/webplugin_delegate_proxy.h
===================================================================
--- content/renderer/webplugin_delegate_proxy.h	(revision 166499)
+++ content/renderer/webplugin_delegate_proxy.h	(working copy)
@@ -207,10 +207,9 @@
   // Draw a graphic indicating a crashed plugin.
   void PaintSadPlugin(WebKit::WebCanvas* canvas, const gfx::Rect& rect);
 
-  // Returns true if the given rectangle is different in the native drawing
-  // context and the current background bitmap.
-  bool BackgroundChanged(gfx::NativeDrawingContext context,
-                         const gfx::Rect& rect);
+  // Returns true if the given rectangle is different in the canvas and the
+  // current background bitmap.
+  bool BackgroundChanged(SkCanvas* canvas, const gfx::Rect& rect);
 
   // Copies the given rectangle from the back-buffer transport_stores_ bitmap to
   // the front-buffer transport_stores_ bitmap.