Protect against null context.

Bug: 22031896
Change-Id: I2da646a30a119c5be07dba8ad71c8e902969454e
diff --git a/src/com/android/dialer/voicemail/VoicemailPlaybackPresenter.java b/src/com/android/dialer/voicemail/VoicemailPlaybackPresenter.java
index 5e75ca7..4cd8c4d 100644
--- a/src/com/android/dialer/voicemail/VoicemailPlaybackPresenter.java
+++ b/src/com/android/dialer/voicemail/VoicemailPlaybackPresenter.java
@@ -272,8 +272,8 @@
      * Must be invoked when the parent activity is paused.
      */
     public void onPause() {
-        int orientation = mContext.getResources().getConfiguration().orientation;
-        if (mInitialOrientation != orientation && mIsPrepared) {
+        if (mContext != null && mIsPrepared
+                && mInitialOrientation != mContext.getResources().getConfiguration().orientation) {
             // If an orientation change triggers the pause, retain the MediaPlayer.
             Log.d(TAG, "onPause: Orientation changed.");
             return;