[animations] Adds metrics for jank on selected layer animations

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 7d9c07b32e4f20ca9d93f3ec46617f1606449cb6..8cfa1c02f85dd8b2858a1237749fd4fecdbdc46c 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -1082,6 +1082,16 @@ LayerAnimatorCollection* Layer::GetLayerAnimatorCollection() {
   return compositor ? compositor->layer_animator_collection() : NULL;
 }
 
+int Layer::GetFrameNumber() const {
+  const Compositor* compositor = GetCompositor();
+  return compositor ? compositor->committed_frame_number() : 0;
+}
+
+float Layer::GetRefreshRate() const {
+  const Compositor* compositor = GetCompositor();
+  return compositor ? compositor->refresh_rate() : 60.0;
+}
+
 cc::Layer* Layer::GetCcLayer() const {
   return cc_layer_;
 }