Created a helper function "FindDiskBySourcePath" in DiskMountManager.

chrome/browser/chromeos/extensions/file_browser_event_router.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 "chrome/browser/chromeos/extensions/file_browser_event_router.h"
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "base/message_loop.h"
 #include "base/stl_util.h"
@@ skipping 322 matching lines @@
     DiskMountManager::MountEvent event_type,
     chromeos::MountError error_code,
     const DiskMountManager::MountPointInfo& mount_info) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   DispatchMountCompletedEvent(event_type, error_code, mount_info);
 
   if (mount_info.mount_type == chromeos::MOUNT_TYPE_DEVICE &&
       event_type == DiskMountManager::MOUNTING) {
     DiskMountManager* disk_mount_manager = DiskMountManager::GetInstance();
-    DiskMountManager::DiskMap::const_iterator disk_it =
-        disk_mount_manager->disks().find(mount_info.source_path);
-    if (disk_it == disk_mount_manager->disks().end()) {
+    const DiskMountManager::Disk* disk =
+        disk_mount_manager->FindDiskBySourcePath(mount_info.source_path);
+    if (!disk)
       return;
-    }
-    DiskMountManager::Disk* disk = disk_it->second;
 
     notifications_->ManageNotificationsOnMountCompleted(
         disk->system_path_prefix(), disk->drive_label(), disk->is_parent(),
         error_code == chromeos::MOUNT_ERROR_NONE,
         error_code == chromeos::MOUNT_ERROR_UNSUPPORTED_FILESYSTEM);
   } else if (mount_info.mount_type == chromeos::MOUNT_TYPE_ARCHIVE) {
     // Clear the "mounted" state for archive files in gdata cache
     // when mounting failed or unmounting succeeded.
     if ((event_type == DiskMountManager::MOUNTING) !=
         (error_code == chromeos::MOUNT_ERROR_NONE)) {
@@ skipping 515 matching lines @@
   return scoped_refptr<RefcountedProfileKeyedService>(
       new FileBrowserEventRouter(profile));
 }
 
 bool FileBrowserEventRouterFactory::ServiceHasOwnInstanceInIncognito() {
   // Explicitly and always allow this router in guest login mode.   see
   // chrome/browser/profiles/profile_keyed_base_factory.h comment
   // for the details.
   return true;
 }