Really fix stop() in samplePlayer when using MediaCodec mode

Make getBufferPercentage() and getPosition() work when the
media is reset.

Change-Id: I7d696fd9b5c62b42aa0d29348e73f1f5755eb075
Signed-off-by: Lajos Molnar <lajos@google.com>
Bug: 9516405

proprietary/samplePlayer/src/com/widevine/demo/MediaCodecView.java

@@ -649,6 +649,10 @@ class MediaCodecView extends SurfaceView
     }
 
     public int getCurrentPosition() {
+        if (mCodecStates == null) {
+            return 0;
+        }
+
         long positionUs = 0;
 
         for (CodecState state : mCodecStates.values()) {
@@ -683,6 +687,10 @@ class MediaCodecView extends SurfaceView
     }
 
     public int getBufferPercentage() {
+        if (mExtractor == null) {
+            return 0;
+        }
+
         long cachedDurationUs = mExtractor.getCachedDuration();
 
         if (cachedDurationUs < 0 || mDurationUs < 0) {