Don't let exiting starting window control system bars

When an activity (appA) starts another activity (appB) behind a starting
window (winS), the app window (winA) of A will lose the window focus.
And then mTopFullscreenOpaqueWindowState will control the system bars
while there is no focused window. WinS might become the controlling
window temporarily before it is removed. The controlling windows could
be:

winS --> winA --> winS (exiting) --> winA --> winB

If the requested visibilities of system bars between winS and winA are
different, system bars might look flickering.

This CL is to let winA keep controlling system bars until the app window
(winB) of appB becomes the focused window. The controlling windows with
the new logic will be:

winS --> winA --> winB

Fix: 322768312
Test: Cold-start `The Spectator` on a device with a pinned taskbar and
      set animator duration scale to animation off. See if taskbar
      flashes on the starting window.
Change-Id: Ic3081d97edf755a3bd2d6ec8703f6ca42bb39dab

1 files changed, 13 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/wm/DisplayPolicy.java b/services/core/java/com/android/server/wm/DisplayPolicy.java
index 5cf9acdbc0d6..7f3df958664c 100644
--- a/services/core/java/com/android/server/wm/DisplayPolicy.java
+++ b/services/core/java/com/android/server/wm/DisplayPolicy.java
@@ -47,6 +47,7 @@ import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_INTERCEPT_GLO
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_LAYOUT_SIZE_EXTENDED_BY_CUTOUT;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_TRUSTED_OVERLAY;
 import static android.view.WindowManager.LayoutParams.PRIVATE_FLAG_UNRESTRICTED_GESTURE_EXCLUSION;
+import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;
 import static android.view.WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_NAVIGATION_BAR;
 import static android.view.WindowManager.LayoutParams.TYPE_NAVIGATION_BAR_PANEL;
@@ -1533,9 +1534,19 @@ public class DisplayPolicy {
         // Check the windows that overlap with system bars to determine system bars' appearance.
         if ((appWindow && attached == null && attrs.isFullscreen())
                 || attrs.type == TYPE_VOICE_INTERACTION) {
-            // Record the top-fullscreen-app-window which will be used to determine system UI
+
+            // If this is the exiting starting window, don't let it control the system bars.
+            // The app window behind it should be the controlling window instead. Reason: when an
+            // activity starts another activity behind a starting window, the app window of the
+            // first activity will lose the window focus. And then mTopFullscreenOpaqueWindowState
+            // will control the system bars. The logic here is to let first app window keep
+            // controlling system bars until the second app window is ready.
+            final boolean exitingStartingWindow =
+                    attrs.type == TYPE_APPLICATION_STARTING && win.mAnimatingExit;
+
+            // Record the top-fullscreen-app-window which will be used to determine the system UI
             // controlling window.
-            if (mTopFullscreenOpaqueWindowState == null) {
+            if (mTopFullscreenOpaqueWindowState == null && !exitingStartingWindow) {
                 mTopFullscreenOpaqueWindowState = win;
             }