Merge "Fix back button not disappearing" into qt-dev

am: e1bdc4b0e8

Change-Id: I7b7eeea1b6c3939c7ddc7d3bd69d8c5bc8e0ae0c

packages/SystemUI/src/com/android/systemui/statusbar/phone/ButtonDispatcher.java

@@ -61,6 +61,7 @@ public class ButtonDispatcher {
     private final AnimatorListenerAdapter mFadeListener = new AnimatorListenerAdapter() {
         @Override
         public void onAnimationEnd(Animator animation) {
+            mFadeAnimator = null;
             setVisibility(getAlpha() == 1 ? View.VISIBLE : View.INVISIBLE);
         }
     };
@@ -143,7 +144,6 @@ public class ButtonDispatcher {
         if (mVisibility == visibility) return;
         if (mFadeAnimator != null) {
             mFadeAnimator.cancel();
-            mFadeAnimator = null;
         }
 
         mVisibility = visibility;
@@ -176,13 +176,13 @@ public class ButtonDispatcher {
             if (mFadeAnimator != null) {
                 mFadeAnimator.cancel();
             }
+            setVisibility(View.VISIBLE);
             mFadeAnimator = ValueAnimator.ofFloat(getAlpha(), alpha);
             mFadeAnimator.setDuration(duration);
             mFadeAnimator.setInterpolator(getAlpha() < alpha ? ALPHA_IN : ALPHA_OUT);
             mFadeAnimator.addListener(mFadeListener);
             mFadeAnimator.addUpdateListener(mAlphaListener);
             mFadeAnimator.start();
-            setVisibility(View.VISIBLE);
         } else {
             mAlpha = alpha;
             final int N = mViews.size();