Force use of and cache render surface.

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 358310bf15e207a0904cc605ff688e7dd257677d..ca39a6e28d7d991bed83900316f1c7bc2eadcc59 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -654,6 +654,10 @@ void Layer::SwitchCCLayerForTest() {
   content_layer_ = new_layer;
 }
 
+void Layer::SetCacheRenderSurface(bool cache_render_surface) {
+  cc_layer_->SetCacheRenderSurface(cache_render_surface);

[danakj, 2017/07/28 22:22:58]

You should leave a comment explaining why Clone() and SwitchToLayer() are not
preserving this, if it is intentional.

[danakj, 2017/07/28 22:32:45]

Adding a comment to explain why not propogated to the new layer in Clone, and
making it preserve it in SwitchToLayer() would LGTM

[wutao, 2017/07/28 23:38:58]

Added a comment and two tests for cloning and switching cc_layer.

+}
+
 void Layer::SetTextureMailbox(
     const viz::TextureMailbox& mailbox,
     std::unique_ptr<viz::SingleReleaseCallback> release_callback,