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

chrome/browser/system_monitor/portable_device_watcher_win.cc

Index: chrome/browser/system_monitor/portable_device_watcher_win.cc
diff --git a/chrome/browser/system_monitor/portable_device_watcher_win.cc b/chrome/browser/system_monitor/portable_device_watcher_win.cc
index 70a5d6800e8177fa850502443841a1abb9bd76a1..4edde6e8074776df36684fe380d42de6923226a1 100644
--- a/chrome/browser/system_monitor/portable_device_watcher_win.cc
+++ b/chrome/browser/system_monitor/portable_device_watcher_win.cc
@@ -516,6 +516,34 @@ void PortableDeviceWatcherWin::OnWindowMessage(UINT event_type, LPARAM data) {
     HandleDeviceDetachEvent(device_id);
 }
 
+bool PortableDeviceWatcherWin::GetMTPStorageInfoFromDeviceId(
+    const std::string& storage_device_id,
+    string16* device_location,
+    string16* storage_object_id) {
+  DCHECK(content::BrowserThread::GetBlockingPool()->RunsTasksOnCurrentThread());

[Peter Kasting, 2012/12/21 18:13:30]

This is scary.  What if the UI thread deletes the object while you're doing
this?  I don't see how you can guarantee this is safe.

[kmadhusu, 2013/01/02 19:48:31]

There is a chance that the UI thread may delete this object while the task
runner is running this code.

A better solution for this problem is to call this function on the UI thread.
Therefore, I created a worker class (MTPGetStorageInfoWorker) to get the device
storage details on the UI thread. 

[Peter Kasting, 2013/01/04 21:13:38]

It might be nice to have DCHECKs that you're on the UI thread in all the
functions that are supposed to run on the UI thread, like you already have in
some of them.

[kmadhusu, 2013/01/04 22:14:32]

Done.

+  DCHECK(device_location);
+  DCHECK(storage_object_id);
+  base::AutoLock locked(lock_);
+  MTPStorageMap::const_iterator storage_map_iter =
+      storage_map_.find(storage_device_id);
+  if (storage_map_iter == storage_map_.end())
+    return false;
+
+  *device_location = storage_map_iter->second.location;
+  MTPDeviceMap::const_iterator device_iter = device_map_.find(*device_location);
+  DCHECK(device_iter != device_map_.end());
+  const StorageObjects& storage_objects = device_iter->second;
+  for (StorageObjects::const_iterator storage_object_iter =
+       storage_objects.begin(); storage_object_iter != storage_objects.end();
+       ++storage_object_iter) {
+    if (storage_device_id == storage_object_iter->object_persistent_id) {
+      *storage_object_id = storage_object_iter->object_temporary_id;
+      break;
+    }
+  }
+  return !storage_object_id->empty();
+}
+
 void PortableDeviceWatcherWin::EnumerateAttachedDevices() {
   DCHECK(media_task_runner_.get());
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
@@ -560,7 +588,7 @@ void PortableDeviceWatcherWin::OnDidHandleDeviceAttachEvent(
   DCHECK(device_details);
   if (!result)
     return;
-
+  base::AutoLock locked(lock_);
   const StorageObjects& storage_objects = device_details->storage_objects;
   const string16& name = device_details->name;
   const string16& location = device_details->location;
@@ -594,6 +622,7 @@ void PortableDeviceWatcherWin::OnDidHandleDeviceAttachEvent(
 void PortableDeviceWatcherWin::HandleDeviceDetachEvent(
     const string16& pnp_device_id) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  base::AutoLock locked(lock_);
   MTPDeviceMap::iterator device_iter = device_map_.find(pnp_device_id);
   if (device_iter == device_map_.end())
     return;