Use .volume_label property for notifying MTP volume labels.

Previously we've abused .volume_id for the purpose, but now we have a
dedicated field for the volume name.

Now the .volume_id field can be arbitrary human unreadable string,
but I'd like to keep it as in the current form since there's also no
other reason to make it cryptic.

BUG=none

Review URL: https://codereview.chromium.org/305053004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@273826 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/file_manager/volume_manager.cc

@@ -729,9 +729,9 @@ void VolumeManager::OnRemovableStorageAttached(
   const std::string base_name = base::UTF16ToUTF8(info.model_name());
 
   // Assign a fresh volume ID based on the volume name.
-  std::string id = kMtpVolumeIdPrefix + base_name;
-  for (int i = 2; mounted_volumes_.count(id); ++i)
-    id = kMtpVolumeIdPrefix + base_name + base::StringPrintf(" (%d)", i);
+  std::string label = base_name;
+  for (int i = 2; mounted_volumes_.count(kMtpVolumeIdPrefix + label); ++i)
+    label = base_name + base::StringPrintf(" (%d)", i);
 
   bool result =
       fileapi::ExternalMountPoints::GetSystemInstance()->RegisterFileSystem(
@@ -750,7 +750,8 @@ void VolumeManager::OnRemovableStorageAttached(
   volume_info.mount_condition = chromeos::disks::MOUNT_CONDITION_NONE;
   volume_info.is_parent = true;
   volume_info.is_read_only = true;
-  volume_info.volume_id = id;
+  volume_info.volume_id = kMtpVolumeIdPrefix + label;
+  volume_info.volume_label = label;
   volume_info.source_path = path;
   volume_info.device_type = chromeos::DEVICE_TYPE_MOBILE;
   DoMountEvent(chromeos::MOUNT_ERROR_NONE, volume_info, false);