Mac gpu: on gpu<->nongpu transitions, make sure to not show uninitialized memory

chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc

Index: chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc
diff --git a/chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc b/chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc
index 3755474a098535b627f6c8d2dbb7bf76f8cebde8..77be3ace4bf562d4e5984afc2ffc9dd21db7fb90 100644
--- a/chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc
+++ b/chrome/browser/renderer_host/accelerated_surface_container_manager_mac.cc
@@ -53,6 +53,13 @@ bool AcceleratedSurfaceContainerManagerMac::IsRootContainer(
       root_container_handle_ == id;
 }
 
+void AcceleratedSurfaceContainerManagerMac::
+    set_gpu_rendering_active(bool active) {
+  if (gpu_rendering_active_ && !active)
+    SetRootSurfaceInvalid();
+  gpu_rendering_active_ = active;
+}
+
 void AcceleratedSurfaceContainerManagerMac::SetSizeAndIOSurface(
     gfx::PluginWindowHandle id,
     int32 width,
@@ -132,6 +139,12 @@ void AcceleratedSurfaceContainerManagerMac::SetSurfaceWasPaintedTo(
     container->set_was_painted_to(surface_id);
 }
 
+void AcceleratedSurfaceContainerManagerMac::SetRootSurfaceInvalid() {
+  AutoLock lock(lock_);
+  if (root_container_)
+    root_container_->set_surface_invalid();
+}
+
 bool AcceleratedSurfaceContainerManagerMac::SurfaceShouldBeVisible(
     gfx::PluginWindowHandle id) const {
   AutoLock lock(lock_);