Only Record Ugliness Histogram for Compositor Side Changes

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 48c6f4732d6cbd83bb327a1107a31baf7146aa6d..f179f30b1a6c5401a40a60514a94eaa88e331ee1 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -188,6 +188,12 @@ class CC_EXPORT LayerTreeImpl {
 
   void ForceRedrawNextActivation() { next_activation_forces_redraw_ = true; }
 
+  void increment_frames_have_been_drawn() {
+    if (frames_have_been_drawn_)

[weiliangc, 2014/07/22 22:01:13]

I use this check to make sure if TreeLayerImpl if has never been updated from
main thread, we are not going to count frames, and consequently not tracking
histogram info.

Is there a better way to achieve this?

[enne (OOO), 2014/07/22 22:35:38]

I'm not sure what you're worried about here.  If a LayerTreeImpl has never been
updated, then it won't have a root layer and can't draw.  (Is this a concrete
issue that you're running into or a more theoretical worry?)

I think you could make your variable a boolean "has_ever_been_drawn" and it'd be
more clear.

+      ++frames_have_been_drawn_;
+  }
+  int frames_have_been_drawn() const { return frames_have_been_drawn_; }
+
   void set_ui_resource_request_queue(const UIResourceRequestQueue& queue);
 
   const LayerImplList& RenderSurfaceLayerList() const;
@@ -330,6 +336,8 @@ class CC_EXPORT LayerTreeImpl {
 
   bool next_activation_forces_redraw_;
 
+  int frames_have_been_drawn_;

[weiliangc, 2014/07/22 22:01:13]

I'm not very happy about this variable name but not sure what else to call it?

+
   ScopedPtrVector<SwapPromise> swap_promise_list_;
 
   UIResourceRequestQueue ui_resource_request_queue_;