Revert of Attempting to resolve a race condition with PowerMonitor

content/gpu/gpu_watchdog_thread.cc

Index: content/gpu/gpu_watchdog_thread.cc
diff --git a/content/gpu/gpu_watchdog_thread.cc b/content/gpu/gpu_watchdog_thread.cc
index 5f8f6197f6db178e34f1b162dfd6e0d32eaf0fc9..940d07e72ac43ae0cb6f36e1b160ab48c6bd7f24 100644
--- a/content/gpu/gpu_watchdog_thread.cc
+++ b/content/gpu/gpu_watchdog_thread.cc
@@ -114,7 +114,9 @@
   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_)
@@ -264,7 +266,9 @@
 }
 
 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() {