Revert of Attempting to resolve a race condition with PowerMonitor

content/gpu/gpu_watchdog_thread.cc

 // Copyright (c) 2012 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.
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "content/gpu/gpu_watchdog_thread.h"
 
@@ skipping 96 matching lines @@
 
 GpuWatchdogThread::~GpuWatchdogThread() {
   // Verify that the thread was explicitly stopped. If the thread is stopped
   // implicitly by the destructor, CleanUp() will not be called.
   DCHECK(!weak_factory_.HasWeakPtrs());
 
 #if defined(OS_WIN)
   CloseHandle(watched_thread_handle_);
 #endif
 
-  base::PowerMonitor::RemoveObserver(this);
+  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  if (power_monitor)
+    power_monitor->RemoveObserver(this);
 
 #if defined(OS_CHROMEOS)
   if (tty_file_)
     fclose(tty_file_);
 #endif
 
   watched_message_loop_->RemoveTaskObserver(&task_observer_);
 }
 
 void GpuWatchdogThread::OnAcknowledge() {
@@ skipping 129 matching lines @@
   terminated = true;
 }
 
 void GpuWatchdogThread::AddPowerObserver() {
   message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&GpuWatchdogThread::OnAddPowerObserver, this));
 }
 
 void GpuWatchdogThread::OnAddPowerObserver() {
-  DCHECK(base::PowerMonitor::AddObserver(this));
+  base::PowerMonitor* power_monitor = base::PowerMonitor::Get();
+  DCHECK(power_monitor);
+  power_monitor->AddObserver(this);
 }
 
 void GpuWatchdogThread::OnSuspend() {
   suspended_ = true;
 
   // When suspending force an acknowledgement to cancel any pending termination
   // tasks.
   OnAcknowledge();
 }
 
@@ skipping 32 matching lines @@
   // not increasing. The other is where either the kernel hangs and never
   // returns to user level or where user level code
   // calls into kernel level repeatedly, giving up its quanta before it is
   // tracked, for example a loop that repeatedly Sleeps.
   return base::TimeDelta::FromMilliseconds(static_cast<int64>(
       (user_time64.QuadPart + kernel_time64.QuadPart) / 10000));
 }
 #endif
 
 }  // namespace content