Check to ensure PowerObservers are added and removed on the same thread

base/power_monitor/power_observer.cc

Index: base/power_monitor/power_observer.cc
diff --git a/base/critical_closure_internal_ios.mm b/base/power_monitor/power_observer.cc
similarity index 51%
copy from base/critical_closure_internal_ios.mm
copy to base/power_monitor/power_observer.cc
index b8fec141b2198e53c2b8e2d4826a1fba7edc0212..4065d6434c23b942a229e01d48f5c535f99d2cd3 100644
--- a/base/critical_closure_internal_ios.mm
+++ b/base/power_monitor/power_observer.cc
@@ -1,17 +1,15 @@
-// Copyright 2014 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.
-
-#include "base/critical_closure.h"
-
-#import <UIKit/UIKit.h>
-
-namespace base {
-namespace internal {
-
-bool IsMultiTaskingSupported() {
-  return [[UIDevice currentDevice] isMultitaskingSupported];
-}
-
-}  // namespace internal
-}  // namespace base
+// Copyright 2014 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.
+
+#include "base/power_monitor/power_observer.h"
+
+namespace base {
+
+PowerObserver::PowerObserver() {
+}
+
+PowerObserver::~PowerObserver() {
+}
+
+}  // namespace base