Created a helper function "FindDiskBySourcePath" in DiskMountManager.

chrome/browser/chromeos/disks/mock_disk_mount_manager.h

 // 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.
 
 #ifndef CHROME_BROWSER_CHROMEOS_DISKS_MOCK_DISK_MOUNT_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_DISKS_MOCK_DISK_MOUNT_MANAGER_H_
 
 #include <string>
 
 #include "base/observer_list.h"
 #include "base/time.h"
 #include "chrome/browser/chromeos/disks/disk_mount_manager.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace chromeos {
 namespace disks {
 
 class MockDiskMountManager : public DiskMountManager {
  public:
   MockDiskMountManager();
   virtual ~MockDiskMountManager();
 
   // DiskMountManager override.
   MOCK_METHOD0(Init, void(void));
   MOCK_METHOD1(AddObserver, void(DiskMountManager::Observer*));
   MOCK_METHOD1(RemoveObserver, void(DiskMountManager::Observer*));
   MOCK_CONST_METHOD0(disks, const DiskMountManager::DiskMap&(void));
+  MOCK_CONST_METHOD1(FindDiskBySourcePath,
+                     const DiskMountManager::Disk*(const std::string&));
   MOCK_CONST_METHOD0(mount_points,
                      const DiskMountManager::MountPointMap&(void));
   MOCK_METHOD0(RequestMountInfoRefresh, void(void));
   MOCK_METHOD4(MountPath, void(const std::string&, const std::string&,
                                const std::string&, MountType));
   MOCK_METHOD1(UnmountPath, void(const std::string&));
   MOCK_METHOD3(GetSizeStatsOnFileThread, void(const std::string&, size_t*,
                                               size_t*));
   MOCK_METHOD1(FormatUnmountedDevice, void(const std::string&));
   MOCK_METHOD1(FormatMountedDevice, void(const std::string&));
@@ skipping 23 matching lines @@
  private:
   // Is used to implement AddObserver.
   void AddObserverInternal(DiskMountManager::Observer* observer);
 
   // Is used to implement RemoveObserver.
   void RemoveObserverInternal(DiskMountManager::Observer* observer);
 
   // Is used to implement disks.
   const DiskMountManager::DiskMap& disksInternal() const { return disks_; }
 
-  // This function is primarily for MediaDeviceNotificationsTest.
   const DiskMountManager::MountPointMap& mountPointsInternal() const;
 
+  // Returns Disk object associated with the |source_path| or NULL on failure.
+  const DiskMountManager::Disk* FindDiskBySourcePathInternal(
+      const std::string& source_path) const;
+
   // Notifies observers about device status update.
   void NotifyDeviceChanged(DiskMountManagerEventType event,
                            const std::string& path);
 
   // Notifies observers about disk status update.
   void NotifyDiskChanged(DiskMountManagerEventType event,
                          const DiskMountManager::Disk* disk);
 
   // The list of observers.
   ObserverList<DiskMountManager::Observer> observers_;
 
   // The list of disks found.
   DiskMountManager::DiskMap disks_;
 
   // The list of existing mount points.
   DiskMountManager::MountPointMap mount_points_;
 
   DISALLOW_COPY_AND_ASSIGN(MockDiskMountManager);
 };
 
 }  // namespace disks
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_DISKS_MOCK_DISK_MOUNT_MANAGER_H_