b/15757378 Expose APIs for listening to active sessions

This allows apps that are registered notification listeners to
listen to the set of active sessions.

Change-Id: I1e108951a5049d138208e88b155c0ec9b95fbdb0

api/current.txt

@@ -15829,7 +15829,14 @@ package android.media.session {
   }
 
   public final class MediaSessionManager {
+    method public void addActiveSessionsListener(android.media.session.MediaSessionManager.SessionListener, android.content.ComponentName);
     method public android.media.session.MediaSession createSession(java.lang.String);
+    method public java.util.List<android.media.session.MediaController> getActiveSessions(android.content.ComponentName);
+  }
+
+  public static abstract class MediaSessionManager.SessionListener {
+    ctor public MediaSessionManager.SessionListener();
+    method public abstract void onActiveSessionsChanged(java.util.List<android.media.session.MediaController>);
   }
 
   public final class MediaSessionToken implements android.os.Parcelable {

media/java/android/media/RemoteController.java

@@ -35,6 +35,7 @@ import android.os.Handler;
 import android.os.Looper;
 import android.os.Message;
 import android.os.SystemClock;
+import android.os.UserHandle;
 import android.util.DisplayMetrics;
 import android.util.Log;
 import android.view.KeyEvent;
@@ -793,12 +794,12 @@ public final class RemoteController
         final ComponentName listenerComponent = new ComponentName(mContext,
                 mOnClientUpdateListener.getClass());
         mSessionManager.addActiveSessionsListener(mSessionListener, listenerComponent,
-                ActivityManager.getCurrentUser());
+                UserHandle.myUserId());
         mSessionListener.onActiveSessionsChanged(mSessionManager
                 .getActiveSessions(listenerComponent));
         if (DEBUG) {
             Log.d(TAG, "Registered session listener with component " + listenerComponent
-                    + " for user " + ActivityManager.getCurrentUser());
+                    + " for user " + UserHandle.myUserId());
         }
     }
 
@@ -809,7 +810,7 @@ public final class RemoteController
         mSessionManager.removeActiveSessionsListener(mSessionListener);
         if (DEBUG) {
             Log.d(TAG, "Unregistered session listener for user "
-                    + ActivityManager.getCurrentUser());
+                    + UserHandle.myUserId());
         }
     }
 

media/java/android/media/session/MediaSessionManager.java

@@ -109,7 +109,6 @@ public final class MediaSessionManager {
      * @param notificationListener The enabled notification listener component.
      *            May be null.
      * @return A list of controllers for ongoing sessions
-     * @hide
      */
     public List<MediaController> getActiveSessions(ComponentName notificationListener) {
         return getActiveSessionsForUser(notificationListener, UserHandle.myUserId());
@@ -145,6 +144,24 @@ public final class MediaSessionManager {
         return controllers;
     }
 
+    /**
+     * Add a listener to be notified when the list of active sessions
+     * changes.This requires the
+     * android.Manifest.permission.MEDIA_CONTENT_CONTROL permission be held by
+     * the calling app. You may also retrieve this list if your app is an
+     * enabled notification listener using the
+     * {@link NotificationListenerService} APIs, in which case you must pass the
+     * {@link ComponentName} of your enabled listener.
+     *
+     * @param sessionListener The listener to add.
+     * @param notificationListener The enabled notification listener component.
+     *            May be null.
+     */
+    public void addActiveSessionsListener(SessionListener sessionListener,
+            ComponentName notificationListener) {
+        addActiveSessionsListener(sessionListener, notificationListener, UserHandle.myUserId());
+    }
+
     /**
      * Add a listener to be notified when the list of active sessions
      * changes.This requires the
@@ -236,8 +253,6 @@ public final class MediaSessionManager {
     /**
      * Listens for changes to the list of active sessions. This can be added
      * using {@link #addActiveSessionsListener}.
-     *
-     * @hide
      */
     public static abstract class SessionListener {
         /**

services/core/java/com/android/server/media/MediaSessionService.java

@@ -383,6 +383,9 @@ public class MediaSessionService extends SystemService implements Monitor {
             // You may not access another user's content as an enabled listener.
             return false;
         }
+        if (DEBUG) {
+            Log.d(TAG, "Checking if enabled notification listener " + compName);
+        }
         if (compName != null) {
             final String enabledNotifListeners = Settings.Secure.getStringForUser(mContentResolver,
                     Settings.Secure.ENABLED_NOTIFICATION_LISTENERS,