Remove home snapshot immediately

If the size of snapshot is mismatched, the removal of the starting
window will be deferred. But if the snapshot target is home, since
it is only presented for unlocking, it is better to dismiss it as
soon as possible to avoid outdated content from being shown on screen
if the windows of home have drawn.

Bug: 161530286
Test: Keep home on top and turn off screen with secured lock. Use
      fingerprint to unlock. If home is drawn fast enough, the
      previous state won't show on screen (e.g. the time on clock).
Change-Id: I103f49eb539f78455ad38f48f9cd853dee51b135
(cherry picked from commit a17c813b)

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

@@ -16,6 +16,7 @@
 
 package com.android.server.wm;
 
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
 import static android.graphics.Color.WHITE;
 import static android.graphics.Color.alpha;
 import static android.view.View.SYSTEM_UI_FLAG_LIGHT_NAVIGATION_BAR;
@@ -142,6 +143,7 @@ class TaskSnapshotSurface implements StartingSurface {
     private final Handler mHandler;
     private boolean mSizeMismatch;
     private final Paint mBackgroundPaint = new Paint();
+    private final int mActivityType;
     private final int mStatusBarColor;
     @VisibleForTesting final SystemBarBackgroundPainter mSystemBarBackgroundPainter;
     private final int mOrientationOnCreation;
@@ -173,6 +175,7 @@ class TaskSnapshotSurface implements StartingSurface {
         final int windowFlags;
         final int windowPrivateFlags;
         final int currentOrientation;
+        final int activityType;
         final InsetsState insetsState;
         synchronized (service.mGlobalLock) {
             final WindowState mainWindow = activity.findMainWindow();
@@ -241,6 +244,7 @@ class TaskSnapshotSurface implements StartingSurface {
             taskBounds = new Rect();
             task.getBounds(taskBounds);
             currentOrientation = topFullscreenOpaqueWindow.getConfiguration().orientation;
+            activityType = activity.getActivityType();
 
             final InsetsPolicy insetsPolicy = topFullscreenOpaqueWindow.getDisplayContent()
                     .getInsetsPolicy();
@@ -261,7 +265,8 @@ class TaskSnapshotSurface implements StartingSurface {
         }
         final TaskSnapshotSurface snapshotSurface = new TaskSnapshotSurface(service, window,
                 surfaceControl, snapshot, layoutParams.getTitle(), taskDescription, sysUiVis,
-                windowFlags, windowPrivateFlags, taskBounds, currentOrientation, insetsState);
+                windowFlags, windowPrivateFlags, taskBounds, currentOrientation, activityType,
+                insetsState);
         window.setOuter(snapshotSurface);
         try {
             session.relayout(window, window.mSeq, layoutParams, -1, -1, View.VISIBLE, 0, -1,
@@ -282,7 +287,7 @@ class TaskSnapshotSurface implements StartingSurface {
     TaskSnapshotSurface(WindowManagerService service, Window window, SurfaceControl surfaceControl,
             TaskSnapshot snapshot, CharSequence title, TaskDescription taskDescription,
             int sysUiVis, int windowFlags, int windowPrivateFlags, Rect taskBounds,
-            int currentOrientation, InsetsState insetsState) {
+            int currentOrientation, int activityType, InsetsState insetsState) {
         mService = service;
         mSurface = service.mSurfaceFactory.get();
         mHandler = new Handler(mService.mH.getLooper());
@@ -298,6 +303,7 @@ class TaskSnapshotSurface implements StartingSurface {
                 windowPrivateFlags, sysUiVis, taskDescription, 1f, insetsState);
         mStatusBarColor = taskDescription.getStatusBarColor();
         mOrientationOnCreation = currentOrientation;
+        mActivityType = activityType;
         mTransaction = mService.mTransactionFactory.get();
     }
 
@@ -305,7 +311,9 @@ class TaskSnapshotSurface implements StartingSurface {
     public void remove() {
         synchronized (mService.mGlobalLock) {
             final long now = SystemClock.uptimeMillis();
-            if (mSizeMismatch && now - mShownTime < SIZE_MISMATCH_MINIMUM_TIME_MS) {
+            if (mSizeMismatch && now - mShownTime < SIZE_MISMATCH_MINIMUM_TIME_MS
+                    // Show the latest content as soon as possible for unlocking to home.
+                    && mActivityType != ACTIVITY_TYPE_HOME) {
                 mHandler.postAtTime(this::remove, mShownTime + SIZE_MISMATCH_MINIMUM_TIME_MS);
                 ProtoLog.v(WM_DEBUG_STARTING_WINDOW,
                         "Defer removing snapshot surface in %dms", (now - mShownTime));

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

@@ -16,6 +16,7 @@
 
 package com.android.server.wm;
 
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD;
 import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.content.res.Configuration.ORIENTATION_PORTRAIT;
 import static android.view.WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS;
@@ -88,7 +89,7 @@ public class TaskSnapshotSurfaceTest extends WindowTestsBase {
                 0 /* systemUiVisibility */, false /* isTranslucent */);
         mSurface = new TaskSnapshotSurface(mWm, new Window(), new SurfaceControl(), snapshot, "Test",
                 createTaskDescription(Color.WHITE, Color.RED, Color.BLUE), sysuiVis, windowFlags, 0,
-                taskBounds, ORIENTATION_PORTRAIT, new InsetsState());
+                taskBounds, ORIENTATION_PORTRAIT, ACTIVITY_TYPE_STANDARD, new InsetsState());
     }
 
     private static TaskDescription createTaskDescription(int background, int statusBar,