Drop accelerated surface when switching off accelerated compositor.

content/browser/renderer_host/render_widget_host_view_win.cc

Index: content/browser/renderer_host/render_widget_host_view_win.cc
===================================================================
--- content/browser/renderer_host/render_widget_host_view_win.cc	(revision 124715)
+++ content/browser/renderer_host/render_widget_host_view_win.cc	(working copy)
@@ -2137,6 +2137,11 @@
           SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
     }
   } else {
+    // Drop the backing store for the accelerated surface when the accelerated
+    // compositor is disabled. Otherwise, a flash of the last presented frame
+    // could appear when it is next enabled.
+    if (accelerated_surface_.get())
+      accelerated_surface_->Suspend();
     hide_compositor_window_at_next_paint_ = true;
   }
 }