Log unsupported MediaButtonReceiver intents.

Bug: None
Change-Id: Idafa3fbc6214dbb15bad5c28d177296bed1926b8
Reviewed-on: https://chromium-review.googlesource.com/1129828Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573455}

chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaButtonReceiver.java

@@ -24,6 +24,11 @@ public abstract class MediaButtonReceiver extends BroadcastReceiver {
 
     @Override
     public void onReceive(Context context, Intent intent) {
+        if (intent == null || !Intent.ACTION_MEDIA_BUTTON.equals(intent.getAction())
+                || !intent.hasExtra(Intent.EXTRA_KEY_EVENT)) {
+            Log.i(TAG, "Received unsupported intent: " + intent);
+        }
+
         intent.setClass(context, getServiceClass());
         Log.i(TAG, "Receive broadcast message, starting foreground service");
         AppHooks.get().startForegroundService(intent);