Fix handles redrawing when not visible

Bug: 137877559
Test: Verify CornerHandleView.onDraw() is no longer called when swiping
along navbar

Change-Id: I10b89fc2d88f93bbbb86bf60db15869d6480a3e2

packages/SystemUI/src/com/android/systemui/CornerHandleView.java

@@ -107,7 +107,9 @@ public class CornerHandleView extends View {
         mPaint.setColor((int) ArgbEvaluator.getInstance().evaluate(darkIntensity,
                 mLightColor,
                 mDarkColor));
-        invalidate();
+        if (getVisibility() == VISIBLE) {
+            invalidate();
+        }
     }
 
     @Override