[animations] Adds metrics for jank on selected layer animations

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 5ed718cfe578327fe79bff22fb1791749cf9f7ea..b1d8287def5be3c3105a26056c1fad081759db2e 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -83,6 +83,7 @@ Compositor::Compositor(const cc::FrameSinkId& frame_sink_id,
 #if defined(USE_AURA)
       window_(nullptr),
 #endif
+      submitted_frame_number_(0),
       widget_valid_(false),
       compositor_frame_sink_requested_(false),
       frame_sink_id_(frame_sink_id),
@@ -522,6 +523,7 @@ void Compositor::DidReceiveCompositorFrameAck() {
 }
 
 void Compositor::DidSubmitCompositorFrame() {
+  ++submitted_frame_number_;
   base::TimeTicks start_time = base::TimeTicks::Now();
   for (auto& observer : observer_list_)
     observer.OnCompositingStarted(this, start_time);