not for commit/review (thread cost tracker)

cc/debug/frame_timing_cost_tracker.cc

Index: cc/debug/frame_timing_cost_tracker.cc
diff --git a/cc/debug/frame_timing_cost_tracker.cc b/cc/debug/frame_timing_cost_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..08fbd9ecf932bea6ead9cf4079509b8f1dccdde5
--- /dev/null
+++ b/cc/debug/frame_timing_cost_tracker.cc
@@ -0,0 +1,35 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/debug/frame_timing_cost_tracker.h"
+
+namespace cc {
+
+FrameTimingCostTracker::FrameTimingCostTracker() {
+}
+
+FrameTimingCostTracker::~FrameTimingCostTracker() {
+}
+
+void FrameTimingCostTracker::Start(int source_frame_number) {
+  worker_thread_cost_tracker_.set_source_frame_to_track(source_frame_number);
+}
+
+void FrameTimingCostTracker::Stop() {
+  worker_thread_cost_tracker_.set_source_frame_to_track(0);
+}
+
+base::TimeDelta FrameTimingCostTracker::GetTotalCost() {
+  return worker_thread_cost_tracker_.get_cost();
+}
+
+void FrameTimingCostTracker::ResetCost() {
+  worker_thread_cost_tracker_.reset_cost();
+}
+
+WorkerThreadCostTracker* FrameTimingCostTracker::GetWorkerThreadCostTracker() {
+  return &worker_thread_cost_tracker_;
+}
+
+}  // namespace cc