blink: Cleanup class forward declarations

third_party/WebKit/Source/platform/scheduler/child/scheduler_helper.h

 // Copyright 2015 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_CHILD_SCHEDULER_HELPER_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_SCHEDULER_HELPER_H_
 
 #include <stddef.h>
 
 #include "base/macros.h"
 #include "base/time/tick_clock.h"
 #include "platform/scheduler/base/task_queue_manager.h"
 #include "platform/scheduler/base/task_queue_selector.h"
 
-namespace base {
-class TickClock;
-}
-
 namespace blink {
 namespace scheduler {
 
 class SchedulerTqmDelegate;
 
 // Common scheduler functionality for default tasks.
 class BLINK_PLATFORM_EXPORT SchedulerHelper
     : public TaskQueueManager::Observer {
  public:
   // Category strings must have application lifetime (statics or
@@ skipping 88 matching lines @@
   const char* tracing_category_;
   const char* disabled_by_default_tracing_category_;
 
   DISALLOW_COPY_AND_ASSIGN(SchedulerHelper);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_SCHEDULER_HELPER_H_