Move Singleton and related structs to namespace base

chrome/browser/chromeos/device_uma.h

 // Copyright 2013 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 CHROME_BROWSER_CHROMEOS_DEVICE_UMA_H_
 #define CHROME_BROWSER_CHROMEOS_DEVICE_UMA_H_
 
 #include "base/basictypes.h"
 #include "ui/events/platform/platform_event_observer.h"
 
+namespace base {
 template <typename T> struct DefaultSingletonTraits;
+}
 
 namespace chromeos {
 
 // A class to record devices' input event details via the UMA system
 class DeviceUMA : public ui::PlatformEventObserver {
  public:
   // Getting instance starts the class automatically if it hasn't been
   // started before.
   static DeviceUMA* GetInstance();
 
   void Stop();
 
  private:
-  friend struct DefaultSingletonTraits<DeviceUMA>;
+  friend struct base::DefaultSingletonTraits<DeviceUMA>;
 
   DeviceUMA();
   ~DeviceUMA() override;
 
   // ui::PlatformEventObserver:
   void WillProcessEvent(const ui::PlatformEvent& event) override;
   void DidProcessEvent(const ui::PlatformEvent& event) override;
 
   // Check CrOS touchpad events to see if the metrics gesture is present
   void CheckTouchpadEvent(XEvent* event);
 
   // Check the incoming events for interesting patterns that we care about.
   void CheckIncomingEvent(XEvent* event);
 
   bool stopped_;
 
   DISALLOW_COPY_AND_ASSIGN(DeviceUMA);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_DEVICE_UMA_H_