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

cc/scheduler/begin_frame_tracker.h

Index: cc/scheduler/begin_frame_tracker.h
diff --git a/cc/scheduler/begin_frame_tracker.h b/cc/scheduler/begin_frame_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..57570cfa74eacbee2fa1aa6ad4344349c7ba83c2
--- /dev/null
+++ b/cc/scheduler/begin_frame_tracker.h
@@ -0,0 +1,45 @@
+// 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.
+
+#ifndef CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_
+#define CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_
+
+#include <set>
+#include <string>
+
+#include "base/debug/trace_event.h"
+#include "base/location.h"
+#include "cc/output/begin_frame_args.h"
+
+#define BEGINFRAMETRACKER_FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION("")
+
+namespace cc {
+
+// Microclass to trace and check properties for correct BeginFrameArgs usage.
+// TODO(mithro): Record stats about the BeginFrameArgs
+class CC_EXPORT BeginFrameTracker {
+ public:
+  explicit BeginFrameTracker(const tracked_objects::Location& location);
+  ~BeginFrameTracker();
+
+  void Start(BeginFrameArgs new_args);
+  const BeginFrameArgs& Get() const;
+  bool HasFinished() const { return !current_finished_at_.is_null(); }
+  void Finish();
+  const BeginFrameArgs& Last() const;
+
+  base::TimeDelta Interval() const;
+
+ private:
+  const tracked_objects::Location location_;
+  const std::string location_string_;
+
+  base::TimeTicks current_updated_at_;
+  BeginFrameArgs current_args_;
+  base::TimeTicks current_finished_at_;
+};
+
+}  // namespace cc
+
+#endif  // CC_SCHEDULER_BEGIN_FRAME_TRACKER_H_