From b7cd0183db0c297f0a724a12a53df3ae8bb9ef30 Mon Sep 17 00:00:00 2001
From: Chilun <chilunhuang@google.com>
Date: Wed, 12 May 2021 18:23:24 +0800
Subject: [PATCH] Clear preferred top focusable root task

When the last activity in the task is finishing and there is no next
activity can be resumed. We will use pre-recorded task which is no
longer visible to resume activity. This will not only fail to resume
activity, but also miss the chance to resume home.

We should not ask an invisible task to resume activity, so this CL is to
clear mPreferredTopFocusableRootTask when we can't find a next focusable
task.

Bug: 183373468
Test: Finish SUW and use back key to finish AllSetActivity
Test: atest ActivityRecordTests TaskTest RootTaskTests
Test: atest DisplayContentTests#testNotResumeHomeRootTaskOnRemovingDisplay
Change-Id: I38b69b9dd25ac1fbf88042fb943f1200c3e33474
---
 services/core/java/com/android/server/wm/Task.java           | 5 +++++
 .../core/java/com/android/server/wm/TaskDisplayArea.java     | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index be01173415a57..5c3c071fc9f8d 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -3080,6 +3080,11 @@ class Task extends WindowContainer<WindowContainer> {
             focusableTask = mRootWindowContainer.getNextFocusableRootTask(this, !allowFocusSelf);
         }
         if (focusableTask == null) {
+            final TaskDisplayArea taskDisplayArea = getDisplayArea();
+            if (taskDisplayArea != null) {
+                // Clear the recorded task since there is no next focusable task.
+                taskDisplayArea.clearPreferredTopFocusableRootTask();
+            }
             return null;
         }
 
diff --git a/services/core/java/com/android/server/wm/TaskDisplayArea.java b/services/core/java/com/android/server/wm/TaskDisplayArea.java
index 368e6dd610e8c..9cbb764aee810 100644
--- a/services/core/java/com/android/server/wm/TaskDisplayArea.java
+++ b/services/core/java/com/android/server/wm/TaskDisplayArea.java
@@ -143,6 +143,7 @@ final class TaskDisplayArea extends DisplayArea<WindowContainer> {
      * unable to resume target root task properly when there are other focusable always-on-top
      * root tasks.
      */
+    @VisibleForTesting
     Task mPreferredTopFocusableRootTask;
 
     /**
@@ -2128,6 +2129,10 @@ final class TaskDisplayArea extends DisplayArea<WindowContainer> {
                 && mDisplayContent.getOrientationRequestingTaskDisplayArea() == this;
     }
 
+    void clearPreferredTopFocusableRootTask() {
+        mPreferredTopFocusableRootTask = null;
+    }
+
     @Override
     protected boolean isTaskDisplayArea() {
         return true;