Move and rename TaskTimeTracker to public interface exposed to WebThread, use in WebPerf Agent.

third_party/WebKit/public/platform/scheduler/base/task_time_tracker.h

 // Copyright 2016 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 THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
-#define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+#ifndef THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+#define THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
 
 #include "base/time/time.h"
 #include "public/platform/WebCommon.h"
 
 namespace blink {
 namespace scheduler {
 
 class BLINK_PLATFORM_EXPORT TaskTimeTracker {
  public:
   TaskTimeTracker() {}
   virtual ~TaskTimeTracker() {}
 
-  virtual void ReportTaskTime(base::TimeTicks startTime,
-                              base::TimeTicks endTime) = 0;
+  virtual void ReportTaskTime(double startTime, double endTime) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TaskTimeTracker);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
-#endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_
+#endif  // THIRD_PARTY_WEBKIT_PUBLIC_PLATFORM_SCHEDULER_BASE_TASK_TIME_TRACKER_H_