Fixes #2948 - updated volume control delegate to handle when ACTION_C…

…ANCELLED (which seems to get triggered in pico) for when a user drags the volume seekbar outside of the area

app/src/common/shared/org/mozilla/vrbrowser/ui/views/VolumeControl.java

@@ -40,13 +40,6 @@ public VolumeControl(Context context, AttributeSet attrs, int defStyleAttr, int
         initialize();
     }
 
-    public interface Delegate {
-        void onVolumeChange(double aVolume);
-        void onSeekBarActionCancelled();
-    }
-
-
-
     @SuppressLint("ClickableViewAccessibility")
     private void initialize() {
         inflate(getContext(), R.layout.volume_control, this);
@@ -56,7 +49,7 @@ private void initialize() {
         mSeekBar.setOnTouchListener((v, event) -> {
 
             if ((event.getAction() == MotionEvent.ACTION_UP) ||(event.getAction() == MotionEvent.ACTION_CANCEL)){
-                if(event.getAction() == MotionEvent.ACTION_CANCEL)
+                if((event.getAction() == MotionEvent.ACTION_CANCEL) && (mDelegate !=null))
                 {
                     mDelegate.onSeekBarActionCancelled();
                 }
@@ -71,7 +64,6 @@ public void setDelegate(Delegate aDelegate) {
         mDelegate = aDelegate;
     }
 
-
     public void setVolume(double aVolume) {
         mVolume = aVolume;
         if (!mTouching) {
@@ -112,4 +104,9 @@ public void onStartTrackingTouch(SeekBar seekBar) {
     public void onStopTrackingTouch(SeekBar seekBar) {
         mTouching = false;
     }
+
+    public interface Delegate {
+        void onVolumeChange(double aVolume);
+        void onSeekBarActionCancelled();
+    }
 }