Scrim: Remove scrim flicker

Remove scrim flicker when we unlock with bouncer.

Bug: 226424400
Test: Manual with device and unit test
Change-Id: Id2922ae6d86d64f42126d11843844c2349e56284

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

@@ -1021,6 +1021,10 @@ public class ScrimController implements ViewTreeObserver.OnPreDrawListener, Dump
         if (aodWallpaperTimeout || occludedKeyguard) {
             mBehindAlpha = 1;
         }
+        // Prevent notification scrim flicker when transitioning away from keyguard.
+        if (mKeyguardStateController.isKeyguardGoingAway()) {
+            mNotificationsAlpha = 0;
+        }
         setScrimAlpha(mScrimInFront, mInFrontAlpha);
         setScrimAlpha(mScrimBehind, mBehindAlpha);
         setScrimAlpha(mNotificationsScrim, mNotificationsAlpha);

packages/SystemUI/tests/src/com/android/systemui/statusbar/phone/ScrimControllerTest.java

@@ -1351,6 +1351,15 @@ public class ScrimControllerTest extends SysuiTestCase {
         ));
     }
 
+    @Test
+    public void keyguardGoingAwayUpdateScrims() {
+        when(mKeyguardStateController.isKeyguardGoingAway()).thenReturn(true);
+        mScrimController.updateScrims();
+        finishAnimationsImmediately();
+        assertThat(mNotificationsScrim.getViewAlpha()).isEqualTo(TRANSPARENT);
+    }
+
+
     private void assertAlphaAfterExpansion(ScrimView scrim, float expectedAlpha, float expansion) {
         mScrimController.setRawPanelExpansionFraction(expansion);
         finishAnimationsImmediately();