Mac: Fix flicker on gpu->nongpu transitions.

chrome/browser/renderer_host/render_widget_host.cc

Index: chrome/browser/renderer_host/render_widget_host.cc
diff --git a/chrome/browser/renderer_host/render_widget_host.cc b/chrome/browser/renderer_host/render_widget_host.cc
index a6efd58ae1847174aec14d0b9229276878560dfa..d5161ed6809dc2c497b9193569e144bf9d25d6f4 100644
--- a/chrome/browser/renderer_host/render_widget_host.cc
+++ b/chrome/browser/renderer_host/render_widget_host.cc
@@ -79,6 +79,9 @@ RenderWidgetHost::RenderWidgetHost(RenderProcessHost* process,
       is_loading_(false),
       is_hidden_(false),
       is_gpu_rendering_active_(false),
+#if defined(OS_MACOSX)
+      needs_to_hide_gpu_view_on_paint_(false),
+#endif
       repaint_ack_pending_(false),
       resize_ack_pending_(false),
       mouse_move_pending_(false),
@@ -823,6 +826,14 @@ void RenderWidgetHost::OnMsgUpdateRect(
     }
   }
 
+#if defined(OS_MACOSX)
+  if (needs_to_hide_gpu_view_on_paint_) {
+    if (view_)
+      view_->GpuRenderingStateDidChange();
+    needs_to_hide_gpu_view_on_paint_ = false;
+  }
+#endif
+
   // ACK early so we can prefetch the next PaintRect if there is a next one.
   // This must be done AFTER we're done painting with the bitmap supplied by the
   // renderer. This ACK is a signal to the renderer that the backing store can
@@ -971,8 +982,14 @@ void RenderWidgetHost::OnMsgGpuRenderingActivated(bool activated) {
 #endif
   is_gpu_rendering_active_ = activated;
 #if defined(OS_MACOSX)
-  if (old_state != is_gpu_rendering_active_ && view_)
-    view_->GpuRenderingStateDidChange();
+  if (old_state != is_gpu_rendering_active_ && view_) {
+    if (is_gpu_rendering_active_) {
+      view_->GpuRenderingStateDidChange();
+    } else {
+      // Delay revealing the non-gpu view until it has been repainted.
+      needs_to_hide_gpu_view_on_paint_ = true;
+    }
+  }
 #endif
 }