[Media Gallery] Added code to support mtp device media file system on Windows.

chrome/browser/system_monitor/portable_device_watcher_win.h

Index: chrome/browser/system_monitor/portable_device_watcher_win.h
diff --git a/chrome/browser/system_monitor/portable_device_watcher_win.h b/chrome/browser/system_monitor/portable_device_watcher_win.h
index dca68cba6faa050b4407208ae733d85b70923d1a..6f7aa6dc44872ef815b9506a0137bd218bb18b6b 100644
--- a/chrome/browser/system_monitor/portable_device_watcher_win.h
+++ b/chrome/browser/system_monitor/portable_device_watcher_win.h
@@ -14,6 +14,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/string16.h"
+#include "base/synchronization/lock.h"
 #include "base/system_monitor/system_monitor.h"
 
 namespace base {
@@ -71,6 +72,14 @@ class PortableDeviceWatcherWin {
   // SystemMonitor notification if appropriate.
   void OnWindowMessage(UINT event_type, LPARAM data);
 
+  // Gets the information of the MTP storage specified by |storage_device_id|.
+  // On success, returns true and fills in |device_location| with device
+  // interface details and |storage_object_id| with storage object temporary
+  // identifier.
+  bool GetMTPStorageInfoFromDeviceId(const std::string& storage_device_id,
+                                     string16* device_location,
+                                     string16* storage_object_id);
+
  private:
   friend class TestPortableDeviceWatcherWin;
 
@@ -105,6 +114,10 @@ class PortableDeviceWatcherWin {
   // Attached media transfer protocol device storage objects map.
   MTPStorageMap storage_map_;
 
+  // The lock to protect |device_map_| and |storage_map_|.
+  // TODO(kmadhusu): Remove this after fixing crbug.com/154835.
+  base::Lock lock_;
+
   // The task runner used to execute tasks that may take a long time and thus
   // should not be performed on the UI thread.
   scoped_refptr<base::SequencedTaskRunner> media_task_runner_;