Fix build

Change-Id: If82d19b1dff8e512c70ee22816210d3409f002f6
diff --git a/src/com/android/mms/ui/SlideshowActivity.java b/src/com/android/mms/ui/SlideshowActivity.java
index c76b178..f85e573 100644
--- a/src/com/android/mms/ui/SlideshowActivity.java
+++ b/src/com/android/mms/ui/SlideshowActivity.java
@@ -377,6 +377,11 @@
         public boolean canSeekForward() {
             return true;
         }
+
+        @Override
+        public int getAudioSessionId() {
+            return 0;
+        }
     }
 
     public void handleEvent(Event evt) {