Have WakeupMessage call Handler#dispatchMessage()

Handler has no fewer than three ways by which a message might be
handled:

    [1] the msg itself contains a callback (msg.callback.run())

    [2] the Handler was instantiated with a Handler.Callback
        (mCallback.handleMessage(msg))

    [3] the Handler instance was a subclass and could have
        overridden handleMessage()

Handler#dispatchMessage() tries to find the correct way to dispatch
a message, check the above in the above order.

Bug: 21859053
Change-Id: I284cf7ace93af167d95d13b297ec42d4bed15992
diff --git a/core/java/com/android/internal/util/WakeupMessage.java b/core/java/com/android/internal/util/WakeupMessage.java
index 7d222c7..46098c5 100644
--- a/core/java/com/android/internal/util/WakeupMessage.java
+++ b/core/java/com/android/internal/util/WakeupMessage.java
@@ -108,7 +108,7 @@
         }
         if (stillScheduled) {
             Message msg = mHandler.obtainMessage(mCmd, mArg1, mArg2, mObj);
-            mHandler.handleMessage(msg);
+            mHandler.dispatchMessage(msg);
             msg.recycle();
         }
     }