Change chrome from statically enabling high resolution timers on windows...

base/message_loop.h

 // Copyright (c) 2006-2008 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 BASE_MESSAGE_LOOP_H_
 #define BASE_MESSAGE_LOOP_H_
 
 #include <queue>
 #include <string>
 
@@ skipping 269 matching lines @@
   void RemoveTaskObserver(TaskObserver* task_observer);
 
 #if defined(OS_WIN)
   typedef base::MessagePumpWin::Dispatcher Dispatcher;
   typedef base::MessagePumpForUI::Observer Observer;
 #elif !defined(OS_MACOSX)
   typedef base::MessagePumpForUI::Dispatcher Dispatcher;
   typedef base::MessagePumpForUI::Observer Observer;
 #endif
 
+  // Returns true if the message loop has high resolution timers enabled.
+  // Provided for testing.
+  bool high_resolution_timers_enabled() {
+#if defined(OS_WIN)
+    return !high_resolution_timer_expiration_.is_null();
+#else
+    return true;
+#endif
+  }
+
+  // When we go into high resolution timer mode, we will stay in hi-res mode
+  // for at least 1s.
+  static const int kHighResolutionTimerModeLeaseTimeMs = 1000;
+
   //----------------------------------------------------------------------------
  protected:
   struct RunState {
     // Used to count how many Run() invocations are on the stack.
     int run_depth;
 
     // Used to record that Quit() was called, or that we should quit the pump
     // once it becomes idle.
     bool quit_received;
 
@@ skipping 147 matching lines @@
   // A null terminated list which creates an incoming_queue of tasks that are
   // aquired under a mutex for processing on this instance's thread. These tasks
   // have not yet been sorted out into items for our work_queue_ vs items that
   // will be handled by the TimerManager.
   TaskQueue incoming_queue_;
   // Protect access to incoming_queue_.
   Lock incoming_queue_lock_;
 
   RunState* state_;
 
+#if defined(OS_WIN)
+  base::TimeTicks high_resolution_timer_expiration_;
+#endif
+
   // The next sequence number to use for delayed tasks.
   int next_sequence_num_;
 
   ObserverList<TaskObserver> task_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageLoop);
 };
 
 //-----------------------------------------------------------------------------
 // MessageLoopForUI extends MessageLoop with methods that are particular to a
@@ skipping 110 matching lines @@
 #endif  // defined(OS_POSIX)
 };
 
 // Do not add any member variables to MessageLoopForIO!  This is important b/c
 // MessageLoopForIO is often allocated via MessageLoop(TYPE_IO).  Any extra
 // data that you need should be stored on the MessageLoop's pump_ instance.
 COMPILE_ASSERT(sizeof(MessageLoop) == sizeof(MessageLoopForIO),
                MessageLoopForIO_should_not_have_extra_member_variables);
 
 #endif  // BASE_MESSAGE_LOOP_H_