[Sync] Move //components/sync to the syncer namespace, take 2.

components/sync/device_info/device_info_tracker.h

 // 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.
 
 #ifndef COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_TRACKER_H_
 #define COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_TRACKER_H_
 
 #include <memory>
 #include <string>
 
 #include "components/sync/device_info/device_info.h"
 
-namespace sync_driver {
+namespace syncer {
 
 // Interface for tracking synced DeviceInfo.
 class DeviceInfoTracker {
  public:
   virtual ~DeviceInfoTracker() {}
 
   // Observer class for listening to device info changes.
   class Observer {
    public:
     virtual void OnDeviceInfoChange() = 0;
   };
 
   // Returns true when DeviceInfo datatype is enabled and syncing.
   virtual bool IsSyncing() const = 0;
   // Gets DeviceInfo the synced device with specified client ID.
   // Returns an empty unique_ptr if device with the given |client_id| hasn't
   // been synced.
   virtual std::unique_ptr<DeviceInfo> GetDeviceInfo(
       const std::string& client_id) const = 0;
   // Gets DeviceInfo for all synced devices (including the local one).
   virtual std::vector<std::unique_ptr<DeviceInfo>> GetAllDeviceInfo() const = 0;
   // Registers an observer to be called on syncing any updated DeviceInfo.
   virtual void AddObserver(Observer* observer) = 0;
   // Unregisters an observer.
   virtual void RemoveObserver(Observer* observer) = 0;
   // Returns the count of active devices.
   virtual int CountActiveDevices() const = 0;
 };
 
-}  // namespace sync_driver
+}  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_DEVICE_INFO_DEVICE_INFO_TRACKER_H_