Address review comments - cancel notification after service stops

Bug: 18026217

Change-Id: I58df7e62970ceff62ddc5d76caee46044a0858fa
diff --git a/MusicDemo/src/main/java/com/example/android/musicservicedemo/MediaNotification.java b/MusicDemo/src/main/java/com/example/android/musicservicedemo/MediaNotification.java
index 45275be..dc03f80 100644
--- a/MusicDemo/src/main/java/com/example/android/musicservicedemo/MediaNotification.java
+++ b/MusicDemo/src/main/java/com/example/android/musicservicedemo/MediaNotification.java
@@ -160,6 +160,7 @@
         mStarted = false;
         mController.unregisterCallback(mCb);
         try {
+            mNotificationManager.cancel(NOTIFICATION_ID);
             mService.unregisterReceiver(this);
         } catch (IllegalArgumentException ex) {
             // ignore if the receiver is not registered.
diff --git a/MusicDemo/src/main/java/com/example/android/musicservicedemo/MusicService.java b/MusicDemo/src/main/java/com/example/android/musicservicedemo/MusicService.java
index c5d3a16..e085275 100644
--- a/MusicDemo/src/main/java/com/example/android/musicservicedemo/MusicService.java
+++ b/MusicDemo/src/main/java/com/example/android/musicservicedemo/MusicService.java
@@ -16,7 +16,6 @@
 
 package com.example.android.musicservicedemo;
 
-import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.media.AudioManager;
@@ -35,7 +34,6 @@
 import android.net.wifi.WifiManager.WifiLock;
 import android.os.Bundle;
 import android.os.Handler;
-import android.os.IBinder;
 import android.os.Message;
 import android.os.PowerManager;
 import android.os.SystemClock;