Hide lockscreen contents from a11y while bouncer is showing

Bug: 20110598
Change-Id: Id65b44b06123dcc4625f46090d7d5c234b0ae951

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

@@ -80,6 +80,14 @@ public class PanelBar extends FrameLayout {
         }
     }
 
+    public void setBouncerShowing(boolean showing) {
+        if (mPanelHolder != null) {
+            mPanelHolder.setImportantForAccessibility(
+                    showing ? IMPORTANT_FOR_ACCESSIBILITY_NO_HIDE_DESCENDANTS
+                            : IMPORTANT_FOR_ACCESSIBILITY_AUTO);
+        }
+    }
+
     public float getBarHeight() {
         return getMeasuredHeight();
     }

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

@@ -3558,6 +3558,7 @@ public class PhoneStatusBar extends BaseStatusBar implements DemoMode,
     @Override
     public void setBouncerShowing(boolean bouncerShowing) {
         super.setBouncerShowing(bouncerShowing);
+        mStatusBarView.setBouncerShowing(bouncerShowing);
         disable(mDisabledUnmodified1, mDisabledUnmodified2, true /* animate */);
     }