Make RotationLockDefaultView inherit directly from ActionableView

ash/system/chromeos/rotation/tray_rotation_lock.h

Index: ash/system/chromeos/rotation/tray_rotation_lock.h
diff --git a/ash/system/chromeos/rotation/tray_rotation_lock.h b/ash/system/chromeos/rotation/tray_rotation_lock.h
index 0576f427f559594edfac90fabbab935897a31ad0..109376c98058f0e393c28c76eebaf31d3b550693 100644
--- a/ash/system/chromeos/rotation/tray_rotation_lock.h
+++ b/ash/system/chromeos/rotation/tray_rotation_lock.h
@@ -56,15 +56,6 @@ class ASH_EXPORT TrayRotationLock
   // currently observing.
   void StopObservingRotation();
 
-  // Removes TrayRotationLock as a ShellObserver if currently observing.
-  void StopObservingShell();
-
-  // True while added as a ScreenOrientationController::Observer.
-  bool observing_rotation_;
-
-  // True while added as a ShellObserver.
-  bool observing_shell_;
-
   DISALLOW_COPY_AND_ASSIGN(TrayRotationLock);
 };