ash: Add a bluetooth entry in the uber tray.

ash/system/tray/system_tray_delegate.h

Index: ash/system/tray/system_tray_delegate.h
diff --git a/ash/system/tray/system_tray_delegate.h b/ash/system/tray/system_tray_delegate.h
index dc5d03316870814d07eaade90a27db965d986d8a..0dffd0fb203c1f8848ddcd10b0060035ac527164 100644
--- a/ash/system/tray/system_tray_delegate.h
+++ b/ash/system/tray/system_tray_delegate.h
@@ -30,6 +30,17 @@ struct ASH_EXPORT NetworkIconInfo {
   std::string service_path;
 };
 
+struct ASH_EXPORT BluetoothDeviceInfo {
+  BluetoothDeviceInfo();
+  ~BluetoothDeviceInfo();
+
+  std::string address;
+  string16 display_name;
+  bool connected;
+};
+
+typedef std::vector<BluetoothDeviceInfo> BluetoothDeviceList;
+
 struct PowerSupplyStatus;
 
 class SystemTrayDelegate {
@@ -93,6 +104,9 @@ class SystemTrayDelegate {
   // Attempts to lock the screen.
   virtual void RequestLockScreen() = 0;
 
+  // Returns a list of available bluetooth devices.
+  virtual BluetoothDeviceList GetAvailableBluetoothDevices() = 0;
+
   // Returns information about the most relevant network. Relevance is
   // determined by the implementor (e.g. a connecting network may be more
   // relevant over a connected network etc.)