Replace FOR_EACH_OBSERVER in chromeos/ with range-based for

chromeos/disks/mock_disk_mount_manager.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.
 
 #include "chromeos/disks/mock_disk_mount_manager.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <utility>
@@ skipping 200 matching lines @@
 
 void MockDiskMountManager::EnsureMountInfoRefreshedInternal(
     const EnsureMountInfoRefreshedCallback& callback,
     bool force) {
   callback.Run(true);
 }
 
 void MockDiskMountManager::NotifyDiskChanged(
     DiskEvent event,
     const DiskMountManager::Disk* disk) {
-  FOR_EACH_OBSERVER(Observer, observers_, OnDiskEvent(event, disk));
+  for (auto& observer : observers_)
+    observer.OnDiskEvent(event, disk);
 }
 
 void MockDiskMountManager::NotifyDeviceChanged(DeviceEvent event,
                                                const std::string& path) {
-  FOR_EACH_OBSERVER(Observer, observers_, OnDeviceEvent(event, path));
+  for (auto& observer : observers_)
+    observer.OnDeviceEvent(event, path);
 }
 
 }  // namespace disks
 }  // namespace chromeos