Extract and dispatch device uuid in media device attached notification message.

chrome/browser/media_gallery/media_device_notifications_chromeos.cc

Index: chrome/browser/media_gallery/media_device_notifications_chromeos.cc
diff --git a/chrome/browser/media_gallery/media_device_notifications_chromeos.cc b/chrome/browser/media_gallery/media_device_notifications_chromeos.cc
index ae45d1563fb26fa80438c33ca086cd80a1332b80..14fd3156e83a4c3436e5a6b2aa5989bb4afd0ade 100644
--- a/chrome/browser/media_gallery/media_device_notifications_chromeos.cc
+++ b/chrome/browser/media_gallery/media_device_notifications_chromeos.cc
@@ -73,6 +73,8 @@ void MediaDeviceNotifications::MountCompleted(
       MountMap::iterator it = mount_map_.find(mount_info.mount_path);
       if (it == mount_map_.end())
         return;
+
+      LOG(ERROR) << "UNMOUNTING DEVICE ID: " << it->second << "\n";
       base::SystemMonitor::Get()->ProcessMediaDeviceDetached(it->second);
       mount_map_.erase(it);
       break;
@@ -101,7 +103,23 @@ void MediaDeviceNotifications::AddMountedPathOnUIThread(
     NOTREACHED();
     return;
   }
-  const std::string device_id_str = base::IntToString(current_device_id_++);
+
+  // Get the media device uuid if exists.
+  const disks::DiskMountManager::DiskMap& disks =
+      disks::DiskMountManager::GetInstance()->disks();
+  disks::DiskMountManager::DiskMap::const_iterator iter =
+       disks.find(mount_info.source_path);
+  std::string device_id_str;
+  if (iter != disks.end()) {

[Lei Zhang, 2012/07/26 02:17:32]

nit: would you mind using |it| instead of |iter| to be consistent with the rest
of the file?

[Lei Zhang, 2012/07/26 02:17:32]

If I understand the disk manager code correctly, I think you should be able to
CHECK_NE(it, disks.end());

[kmadhusu, 2012/07/26 17:01:23]

Done.

[kmadhusu, 2012/07/26 17:01:23]

I was not able to use CHECK_NE. Why do you think it should work?

+    const disks::DiskMountManager::Disk& disk = *iter->second;
+    device_id_str = disk.fs_uuid();
+  }
+  // TODO(kmadhusu, thestig): Set the unique id for mtp devices.
+  if (device_id_str.empty())
+    device_id_str =  base::IntToString(current_device_id_++);

[Lei Zhang, 2012/07/26 02:17:32]

You should get rid of |current_device_id_|. Trying to handle the failure by
getting a device id this way does not fall in line with the notion that the
device id should be unique and persistent across device attachments.

I would rather we just fail and have a UMA to keep track of how often this
occurs.

[kmadhusu, 2012/07/26 17:01:23]

Done.

+
+  LOG(ERROR) << "MOUNTING DEVICE ID: " << device_id_str << "\n";
+
   mount_map_.insert(std::make_pair(mount_info.mount_path, device_id_str));
   base::SystemMonitor::Get()->ProcessMediaDeviceAttached(
       device_id_str,