Abort rather than crashing when MediaSessionService is started w/o WL.

When an intent attempts to start MediaSessionService but WebLayer has
not been loaded, the service will no-op instead of throwing an
exception.

Bug: b/167388918
Change-Id: I0f191d0f620016c8ee072e0953d10ad1c257fa15
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2388404Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Clark DuVall <cduvall@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803594}

weblayer/public/java/org/chromium/weblayer/MediaSessionService.java

@@ -25,12 +25,6 @@ public class MediaSessionService extends Service {
     // A helper to automatically pause the media session when a user removes headphones.
     private BroadcastReceiver mAudioBecomingNoisyReceiver;
 
-    public MediaSessionService() {
-        if (WebLayer.getSupportedMajorVersionInternal() < 85) {
-            throw new UnsupportedOperationException();
-        }
-    }
-
     @Override
     public IBinder onBind(Intent intent) {
         return null;
@@ -40,6 +34,11 @@ public class MediaSessionService extends Service {
     public void onCreate() {
         super.onCreate();
 
+        if (!WebLayer.hasWebLayerInitializationStarted()) {
+            stopSelf();
+            return;
+        }
+
         mAudioBecomingNoisyReceiver = new BroadcastReceiver() {
             @Override
             public void onReceive(Context context, Intent intent) {
@@ -61,6 +60,8 @@ public class MediaSessionService extends Service {
     public void onDestroy() {
         super.onDestroy();
 
+        if (mAudioBecomingNoisyReceiver == null) return;
+
         try {
             getWebLayer().getImpl().onMediaSessionServiceDestroyed();
         } catch (RemoteException e) {
@@ -73,7 +74,10 @@ public class MediaSessionService extends Service {
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
         try {
-            getWebLayer().getImpl().onMediaSessionServiceStarted(ObjectWrapper.wrap(this), intent);
+            if (WebLayer.hasWebLayerInitializationStarted()) {
+                getWebLayer().getImpl().onMediaSessionServiceStarted(
+                        ObjectWrapper.wrap(this), intent);
+            }
         } catch (RemoteException e) {
             throw new RuntimeException(e);
         }

weblayer/public/java/org/chromium/weblayer/WebLayer.java

@@ -157,6 +157,11 @@ public class WebLayer {
         return sLoader;
     }
 
+    /** Returns whether WebLayer loading has at least started. */
+    static boolean hasWebLayerInitializationStarted() {
+        return sLoader != null;
+    }
+
     IWebLayer getImpl() {
         return mImpl;
     }