MediaRouter: Fix comments.

Change-Id: I4360d9cf64f4be0276e126cd0ba850535b851f83
diff --git a/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java b/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
index e5988ad..4ff4bee 100644
--- a/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
+++ b/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
@@ -447,9 +447,9 @@
 
     private boolean isPlaybackControlLayoutNeeded() {
         // If a route does not support remote playback, it means that the route is dedicated for
-        // audio or video mirroring such as A2DP speaker or headset. In this case, the route
+        // audio or video streaming such as A2DP speaker or headset. In this case, the route
         // provider does not provide any playback information such as metadata or playback status.
-        // But, for live video, playback control layout shows a message that the screen is being
+        // But, for live video, playback control UI shows a message that the screen is being
         // mirrored, while it does not show anything for live audio.
         return mCustomControlView == null && (mDescription != null || mState != null)
                 && (mRoute.supportsControlCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK)