blink: Cleanup class forward declarations

third_party/WebKit/Source/platform/scheduler/base/queueing_time_estimator.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_RENDERER_QUEUEING_TIME_ESTIMATOR_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_QUEUEING_TIME_ESTIMATOR_H_
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "public/platform/WebCommon.h"
 
-namespace base {
-class TickClock;
-}
-
 namespace blink {
 namespace scheduler {
 
 // Records the expected queueing time for a high priority task occurring
 // randomly during each interval of length |window_duration|.
 class BLINK_PLATFORM_EXPORT QueueingTimeEstimator {
  public:
   class BLINK_PLATFORM_EXPORT Client {
    public:
     virtual void OnQueueingTimeForWindowEstimated(
@@ skipping 18 matching lines @@
   base::TimeDelta window_duration_;
   base::TimeTicks window_start_time_;
 
   DISALLOW_COPY_AND_ASSIGN(QueueingTimeEstimator);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_QUEUEING_TIME_ESTIMATOR_H_