Merge 66631 - Mac: Only clear the background of CoreAnimation plugins if we'r...

webkit/glue/plugins/webplugin_delegate_impl_mac.mm

Index: webkit/glue/plugins/webplugin_delegate_impl_mac.mm
===================================================================
--- webkit/glue/plugins/webplugin_delegate_impl_mac.mm	(revision 66641)
+++ webkit/glue/plugins/webplugin_delegate_impl_mac.mm	(working copy)
@@ -981,14 +981,15 @@
   if (!windowed_handle())
     return;
 
-  surface_->StartDrawing();
-
   [renderer_ beginFrameAtTime:CACurrentMediaTime() timeStamp:NULL];
   if (CGRectIsEmpty([renderer_ updateBounds])) {
     // If nothing has changed, we are done.
     [renderer_ endFrame];
     return;
   }
+
+  surface_->StartDrawing();
+
   CGRect layerRect = [layer_ bounds];
   [renderer_ addUpdateRect:layerRect];
   [renderer_ render];