Fix 5380695 Lockscreen transport control must reflect error state

When a RemoteControlClient reports an error for its playstate,
 make the play/pause button display the warning platform icon.

Note that a specific image description is not available for this
 state at this time, but the one being used (the same as for the
 play icon) is valid as it correctly describes the action the
 button performs.

Change-Id: I59aadab3fe5bcc09a2f7be0b9e4cffb0c500e865

Author: jmtrivi

core/java/com/android/internal/widget/TransportControlView.java

@@ -339,6 +339,13 @@ private void updatePlayPauseState(int state) {
         final int imageResId;
         final int imageDescId;
         switch (state) {
+            case RemoteControlClient.PLAYSTATE_ERROR:
+                imageResId = com.android.internal.R.drawable.stat_sys_warning;
+                // TODO use more specific image description string for warning, but here the "play"
+                //      message is still valid because this button triggers a play command.
+                imageDescId = com.android.internal.R.string.lockscreen_transport_play_description;
+                break;
+
             case RemoteControlClient.PLAYSTATE_PLAYING:
                 imageResId = com.android.internal.R.drawable.ic_media_pause;
                 imageDescId = com.android.internal.R.string.lockscreen_transport_pause_description;