cros: Move TrayBluetoothHelper out of chrome into ash

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 2484c10fb8a4abcb95218b24b3f04afd8260d854..d4fdd745c0218aded2f8da8ec3240e13c012f25d 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -121,6 +121,7 @@ class ResizeShadowController;
 class ResolutionNotificationController;
 class RootWindowController;
 class ScopedOverviewAnimationSettingsFactoryAura;
+class ScreenLayoutObserver;
 class ScreenOrientationController;
 class ScreenshotController;
 class ScreenPinningController;
@@ -136,8 +137,8 @@ class SystemGestureEventFilter;
 class SystemModalContainerEventFilter;
 class SystemTray;
 class ToplevelWindowEventHandler;
-class ScreenLayoutObserver;
 class ToastManager;
+class TrayBluetoothHelper;
 class VirtualKeyboardController;
 class VideoActivityNotifier;
 class VideoDetector;
@@ -408,6 +409,10 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
     return screen_orientation_controller_.get();
   }
 
+  TrayBluetoothHelper* tray_bluetooth_helper() {
+    return tray_bluetooth_helper_.get();
+  }
+
   VirtualKeyboardController* virtual_keyboard_controller() {
     return virtual_keyboard_controller_.get();
   }
@@ -636,6 +641,8 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
       resolution_notification_controller_;
   std::unique_ptr<BluetoothNotificationController>
       bluetooth_notification_controller_;
+  // The helper persists whereas system tray items are created on menu open.

[msw, 2017/03/20 23:47:07]

Hmm, I'm not sure this is the best place for this comment, if it's needed at
all. I'm not sure that anyone would assume that a 'TrayBluetoothHelper' would
have a lifetime tied to when the system tray menu is open.

[James Cook, 2017/03/21 00:18:08]

Agreed. Removed comment.

+  std::unique_ptr<TrayBluetoothHelper> tray_bluetooth_helper_;
   std::unique_ptr<VirtualKeyboardController> virtual_keyboard_controller_;
   std::unique_ptr<chromeos::AudioA11yController> audio_a11y_controller_;
   // Controls video output device state.