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..eddaf7f49abb3506f20d4a86f1c8516e2a6aeb1a 100644
--- a/chrome/browser/media_gallery/media_device_notifications_chromeos.cc
+++ b/chrome/browser/media_gallery/media_device_notifications_chromeos.cc
@@ -8,6 +8,7 @@
 
 #include "base/file_path.h"
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/stl_util.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
@@ -18,8 +19,7 @@ namespace chromeos {
 
 using content::BrowserThread;
 
-MediaDeviceNotifications::MediaDeviceNotifications()
-    : current_device_id_(0) {
+MediaDeviceNotifications::MediaDeviceNotifications() {
   DCHECK(disks::DiskMountManager::GetInstance());
   disks::DiskMountManager::GetInstance()->AddObserver(this);
 }
@@ -101,7 +101,29 @@ void MediaDeviceNotifications::AddMountedPathOnUIThread(
     NOTREACHED();
     return;
   }
-  const std::string device_id_str = base::IntToString(current_device_id_++);
+
+  // Get the media device uuid if exists.

[Ben Chan, 2012/07/26 17:11:18]

nit: perhaps turning 105 - 114 into method

[kmadhusu, 2012/07/26 17:23:05]

Done.

+  const disks::DiskMountManager::DiskMap& disks =
+      disks::DiskMountManager::GetInstance()->disks();
+  disks::DiskMountManager::DiskMap::const_iterator it =
+      disks.find(mount_info.source_path);
+  std::string device_id_str;
+  if (it != disks.end()) {
+    const disks::DiskMountManager::Disk& disk = *it->second;
+    device_id_str = disk.fs_uuid();
+  }
+
+  // Keep track of device uuid, to see how often we receive empty uuid values.
+  static base::Histogram* media_device_uuid_available(NULL);
+  if (!media_device_uuid_available) {
+    media_device_uuid_available = base::BooleanHistogram::FactoryGet(
+        "MediaDeviceNotification.device_uuid_available",
+        base::Histogram::kUmaTargetedHistogramFlag);
+  }
+  media_device_uuid_available->AddBoolean(!device_id_str.empty());
+  if (device_id_str.empty())
+    return;
+
   mount_map_.insert(std::make_pair(mount_info.mount_path, device_id_str));
   base::SystemMonitor::Get()->ProcessMediaDeviceAttached(
       device_id_str,