[Win, MediaGallery] Enumerate and handle mtp device attach/detach events.

chrome/browser/system_monitor/removable_device_constants.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_SYSTEM_MONITOR_REMOVABLE_DEVICE_CONSTANTS_H_
 #define CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_CONSTANTS_H_
 
 #include "build/build_config.h"
+#include "base/string16.h"
 
 namespace chrome {
 
 // Prefix constants used in device unique id.
 extern const char kFSUniqueIdPrefix[];
 extern const char kVendorModelSerialPrefix[];
 
+// Delimiter constants used in device label and unique id.
+extern const char kNonSpaceDelim[];
+extern const char kSpaceDelim[];
+
 #if defined(OS_LINUX)
 // Delimiter constants used in device label to specify data storage id.
 extern const char kLeftParen[];
 extern const char kRightParen[];
 
 extern const char kVendorModelVolumeStoragePrefix[];
 #endif
 
-// Delimiter constants used in device label and unique id.
-extern const char kNonSpaceDelim[];
-extern const char kSpaceDelim[];
+#if defined(OS_WIN)
+// Delimiter constant used in mtp device storage unique id.
+extern const char16 kMtpDeviceStorageIdPrefix[];
+#endif
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_SYSTEM_MONITOR_REMOVABLE_DEVICE_CONSTANTS_H_