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

third_party/WebKit/public/platform/WebThread.h

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 38 matching lines @@
         virtual void run(double deadlineSeconds) = 0;
     };
 
     class BLINK_PLATFORM_EXPORT TaskObserver {
     public:
         virtual ~TaskObserver() { }
         virtual void willProcessTask() = 0;
         virtual void didProcessTask() = 0;
     };
 
+    class BLINK_PLATFORM_EXPORT TaskTimeObserver : public TaskObserver {
+    public:
+        virtual ~TaskTimeObserver() { }
+        virtual void reportTaskTime(double startTime, double endTime) = 0;
+    };
 
     // Returns a WebTaskRunner bound to the underlying scheduler's default task queue.
     virtual WebTaskRunner* getWebTaskRunner() { return nullptr; }
 
     virtual bool isCurrentThread() const = 0;
     virtual PlatformThreadId threadId() const { return 0; }
 
     virtual void addTaskObserver(TaskObserver*) { }
     virtual void removeTaskObserver(TaskObserver*) { }
+    virtual void addTaskTimeObserver(TaskTimeObserver*) { }
+    virtual void removeTaskTimeObserver(TaskTimeObserver*) { }
 
     // Returns the scheduler associated with the thread.
     virtual WebScheduler* scheduler() const = 0;
 
     virtual ~WebThread() { }
 };
 
 } // namespace blink
 
 #endif