When video not seekable, don't show the scrubber

bug:7117365

Change-Id: I133ea68eaebf1d875a27336ac524d785efe71cc2
diff --git a/src/com/android/gallery3d/app/MoviePlayer.java b/src/com/android/gallery3d/app/MoviePlayer.java
index 00e4cd6..ce91834 100644
--- a/src/com/android/gallery3d/app/MoviePlayer.java
+++ b/src/com/android/gallery3d/app/MoviePlayer.java
@@ -25,7 +25,6 @@
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
 import android.content.IntentFilter;
-import android.graphics.Color;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
 import android.net.Uri;
@@ -135,6 +134,17 @@
                 return true;
             }
         });
+        mVideoView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
+            @Override
+            public void onPrepared(MediaPlayer player) {
+                if (!mVideoView.canSeekForward() || !mVideoView.canSeekBackward()) {
+                    mController.setSeekable(false);
+                } else {
+                    mController.setSeekable(true);
+                }
+                setProgress();
+            }
+        });
 
         // The SurfaceView is transparent before drawing the first frame.
         // This makes the UI flashing when open a video. (black -> old screen