Add IPC allowing GPU process to tell browser process to temporarily drop a front buffer.

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 119674)
+++ content/browser/renderer_host/render_widget_host_view_win.cc	(working copy)
@@ -2140,6 +2140,13 @@
   RenderWidgetHost::AcknowledgePostSubBuffer(params.route_id, gpu_host_id);
 }
 
+void RenderWidgetHostViewWin::AcceleratedSurfaceSuspend() {
+    if (!accelerated_surface_.get())
+      return;
+
+    accelerated_surface_->Suspend();
+}
+
 void RenderWidgetHostViewWin::SetAccessibilityFocus(int acc_obj_id) {
   if (!render_widget_host_)
     return;