Don't unnecessarily paint pixles when doing optimized always-on-top pepper pa...

chrome/renderer/render_widget.cc

Index: chrome/renderer/render_widget.cc
===================================================================
--- chrome/renderer/render_widget.cc	(revision 71513)
+++ chrome/renderer/render_widget.cc	(working copy)
@@ -441,7 +441,7 @@
     // the plugin. Unlike the DoDeferredUpdate case, an extra copy is still
     // required.
     optimized_instance->Paint(webkit_glue::ToWebCanvas(canvas),
-                              optimized_copy_location, optimized_copy_location);
+                              optimized_copy_location, rect);
   } else {
     // Normal painting case.
     webwidget_->paint(webkit_glue::ToWebCanvas(canvas), rect);
@@ -530,6 +530,8 @@
       !is_accelerated_compositing_active_ &&
       GetBitmapForOptimizedPluginPaint(bounds, &dib, &optimized_copy_location,
                                        &optimized_copy_rect)) {
+    // Only update the part of the plugin that actually changed.
+    optimized_copy_rect = optimized_copy_rect.Intersect(bounds);
     bounds = optimized_copy_location;
     copy_rects.push_back(optimized_copy_rect);
     dib_id = dib->id();