Created a helper function "FindDiskBySourcePath" in DiskMountManager.

chrome/browser/media_gallery/media_device_notifications_chromeos.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.
 
 // chromeos::MediaDeviceNotifications implementation.
 
 #include "chrome/browser/media_gallery/media_device_notifications_chromeos.h"
 
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/media_gallery/media_device_notifications_utils.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace chromeos {
 
 namespace {
 
 bool GetDeviceInfo(const std::string& source_path, std::string* device_id,
                    string16* device_label) {
   // Get the media device uuid and label if exists.
-  const disks::DiskMountManager::DiskMap& disks =
-      disks::DiskMountManager::GetInstance()->disks();
-  disks::DiskMountManager::DiskMap::const_iterator it = disks.find(source_path);
-  if (it == disks.end())
+  const disks::DiskMountManager::Disk* disk =
+      disks::DiskMountManager::GetInstance()->FindDiskBySourcePath(source_path);
+  if (!disk)
     return false;
 
-  const disks::DiskMountManager::Disk& disk = *(it->second);
-  *device_id = disk.fs_uuid();
+  *device_id = disk->fs_uuid();
 
   // TODO(kmadhusu): If device label is empty, extract vendor and model details
   // and use them as device_label.
-  *device_label = UTF8ToUTF16(disk.device_label().empty() ?
+  *device_label = UTF8ToUTF16(disk->device_label().empty() ?
                               FilePath(source_path).BaseName().value() :
-                              disk.device_label());
+                              disk->device_label());
   return true;
 }
 
 }  // namespace
 
 using content::BrowserThread;
 
 MediaDeviceNotifications::MediaDeviceNotifications() {
   DCHECK(disks::DiskMountManager::GetInstance());
   disks::DiskMountManager::GetInstance()->AddObserver(this);
@@ skipping 105 matching lines @@
 
   mount_map_.insert(std::make_pair(mount_info.mount_path, device_id));
   base::SystemMonitor::Get()->ProcessMediaDeviceAttached(
       device_id,
       device_label,
       base::SystemMonitor::TYPE_PATH,
       mount_info.mount_path);
 }
 
 }  // namespace chrome