cc: Measure compositor timing with finer granularity

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 2bbf75c8a3b15ce3dd6ab57f3fdb5d8e11e2df26..9beba7b661576b4abf41c55e943316d58306c575 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -290,6 +290,9 @@ void SingleThreadProxy::CommitComplete() {
       << "Activation is expected to have synchronously occurred by now.";
   DCHECK(commit_blocking_task_runner_);
 
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->DidCommit();
+
   // Notify commit complete on the impl side after activate to satisfy any
   // SetNextCommitWaitsForActivation calls.
   layer_tree_host_impl_->CommitComplete();
@@ -455,6 +458,12 @@ void SingleThreadProxy::DidActivateSyncTree() {
   CommitComplete();
 }
 
+void SingleThreadProxy::WillPrepareTiles() {
+  DCHECK(Proxy::IsImplThread());
+  if (scheduler_on_impl_thread_)
+    scheduler_on_impl_thread_->WillPrepareTiles();
+}
+
 void SingleThreadProxy::DidPrepareTiles() {
   DCHECK(Proxy::IsImplThread());
   if (scheduler_on_impl_thread_)