Update condition for when to show letterbox

Makes sure we show the letterbox even during the period a window is
requesting to be redrawn because of a layout change (i.e. orientation
change) or for any other reason, if the window's associated surface
is still visible.

This avoids seeing a letterbox flicker when this happens.

Bug: 256052489
Bug: 266635069
Test: Launch the dialer for a phone call or Google wallet app on a large
screen device and make sure the letterbox doesn't flicker on launch.

Change-Id: I7911ddc45c1ff839cc22be09caa5cc7ddc022d45

services/core/java/com/android/server/wm/LetterboxUiController.java

@@ -1001,7 +1001,7 @@ final class LetterboxUiController {
 
     @VisibleForTesting
     boolean shouldShowLetterboxUi(WindowState mainWindow) {
-        return isSurfaceReadyAndVisible(mainWindow) && mainWindow.areAppWindowBoundsLetterboxed()
+        return isSurfaceVisible(mainWindow) && mainWindow.areAppWindowBoundsLetterboxed()
                 // Check for FLAG_SHOW_WALLPAPER explicitly instead of using
                 // WindowContainer#showWallpaper because the later will return true when this
                 // activity is using blurred wallpaper for letterbox background.
@@ -1009,11 +1009,8 @@ final class LetterboxUiController {
     }
 
     @VisibleForTesting
-    boolean isSurfaceReadyAndVisible(WindowState mainWindow) {
-        boolean surfaceReady = mainWindow.isDrawn() // Regular case
-                // Waiting for relayoutWindow to call preserveSurface
-                || mainWindow.isDragResizeChanged();
-        return surfaceReady && (mActivityRecord.isVisible()
+    boolean isSurfaceVisible(WindowState mainWindow) {
+        return mainWindow.isOnScreen() && (mActivityRecord.isVisible()
                 || mActivityRecord.isVisibleRequested());
     }
 

services/tests/wmtests/src/com/android/server/wm/LetterboxUiControllerTest.java

@@ -494,6 +494,7 @@ public class LetterboxUiControllerTest extends WindowTestsBase {
         doReturn(insets).when(mainWindow).getInsetsState();
         doReturn(attrs).when(mainWindow).getAttrs();
         doReturn(true).when(mainWindow).isDrawn();
+        doReturn(true).when(mainWindow).isOnScreen();
         doReturn(false).when(mainWindow).isLetterboxedForDisplayCutout();
         doReturn(true).when(mainWindow).areAppWindowBoundsLetterboxed();
         doReturn(true).when(mLetterboxConfiguration).isLetterboxActivityCornersRounded();

services/tests/wmtests/src/com/android/server/wm/SizeCompatTests.java

@@ -502,7 +502,7 @@ public class SizeCompatTests extends WindowTestsBase {
 
         spyOn(mActivity.mLetterboxUiController);
         doReturn(true).when(mActivity.mLetterboxUiController)
-                .isSurfaceReadyAndVisible(any());
+                .isSurfaceVisible(any());
 
         assertTrue(mActivity.mLetterboxUiController.shouldShowLetterboxUi(
                 mActivity.findMainWindow()));