cc: Adding BeginFrameTracker object and removing Now() from LTHI.

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 6498f0e0996ce49b310eb9a1c7a5d83bcfbfe4df..dd6f7b4a50d3df75c7d22b720849e2ee39dbee82 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -494,6 +494,7 @@ void SingleThreadProxy::CompositeImmediately(base::TimeTicks frame_begin_time) {
     BeginFrameArgs begin_frame_args(BeginFrameArgs::Create(
         BEGINFRAME_FROM_HERE, frame_begin_time, base::TimeTicks(),
         BeginFrameArgs::DefaultInterval(), BeginFrameArgs::SYNCHRONOUS));
+    layer_tree_host_impl_->UpdateCurrentBeginFrameArgs(begin_frame_args);
     DoBeginMainFrame(begin_frame_args);
     DoCommit();
 
@@ -519,6 +520,8 @@ void SingleThreadProxy::CompositeImmediately(base::TimeTicks frame_begin_time) {
     // another draw will never be scheduled, so break remaining promises.
     layer_tree_host_impl_->active_tree()->BreakSwapPromises(
         SwapPromise::SWAP_FAILS);
+
+    layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();
   }
 }
 
@@ -593,7 +596,6 @@ DrawResult SingleThreadProxy::DoComposite(base::TimeTicks frame_begin_time,
 
     bool start_ready_animations = draw_frame;
     layer_tree_host_impl_->UpdateAnimationState(start_ready_animations);
-    layer_tree_host_impl_->ResetCurrentBeginFrameArgsForNextFrame();

[brianderson, 2014/12/18 02:01:38]

Why does this need to move?

[mithro-old, 2014/12/18 17:22:41]

Because it's currently in the wrong place as code in the STP between this
location and the new location still uses the BFA (as found by tests).

This means currently in production that code is not just getting values affected
by the delay to first BeginFrame, it's getting horrible values which are just
Now() when ever it's called.

 
     timing_history_.DidFinishDrawing();
   }