From f191f9a73b991e89065d9981bb79b0d29d2bb7ec Mon Sep 17 00:00:00 2001
From: Riddle Hsu <riddlehsu@google.com>
Date: Mon, 10 Aug 2020 15:40:46 +0800
Subject: [PATCH] Resume next activity if pausing app died

If the top activity is crashed before showing any window, when its
process reported dead, it will be regarded as no visible activity
and no need to resume next activity. That may lead to the next top
activity remains in paused state and may be unresponsive.

Bug: 159951007
Test: atest ActivityTaskManagerServiceTests# \
      testResumeNextActivityOnCrashedAppDied
Change-Id: I635fceb9cf7b782f6ffbb9ebef7cb69053f64a0b
---
 .../core/java/com/android/server/wm/Task.java |  6 ++++-
 .../server/wm/WindowProcessController.java    |  5 ++++-
 .../wm/ActivityTaskManagerServiceTests.java   | 22 +++++++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index be0815b060515..2b6e5ef71f68b 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -7056,17 +7056,21 @@ class Task extends WindowContainer<WindowContainer> {
     /**
      * Reset local parameters because an app's activity died.
      * @param app The app of the activity that died.
+     * @return {@code true} if the process of the pausing activity is died.
      */
-    void handleAppDied(WindowProcessController app) {
+    boolean handleAppDied(WindowProcessController app) {
+        boolean isPausingDied = false;
         if (mPausingActivity != null && mPausingActivity.app == app) {
             if (DEBUG_PAUSE || DEBUG_CLEANUP) Slog.v(TAG_PAUSE,
                     "App died while pausing: " + mPausingActivity);
             mPausingActivity = null;
+            isPausingDied = true;
         }
         if (mLastPausedActivity != null && mLastPausedActivity.app == app) {
             mLastPausedActivity = null;
             mLastNoHistoryActivity = null;
         }
+        return isPausingDied;
     }
 
     boolean dump(FileDescriptor fd, PrintWriter pw, boolean dumpAll, boolean dumpClient,
diff --git a/services/core/java/com/android/server/wm/WindowProcessController.java b/services/core/java/com/android/server/wm/WindowProcessController.java
index 70c30c9180d7a..ab6e35b452a0f 100644
--- a/services/core/java/com/android/server/wm/WindowProcessController.java
+++ b/services/core/java/com/android/server/wm/WindowProcessController.java
@@ -1201,7 +1201,10 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
 
             final Task rootTask = r.getRootTask();
             if (rootTask != null) {
-                rootTask.handleAppDied(this);
+                // There may be a pausing activity that hasn't shown any window and was requested
+                // to be hidden. But pausing is also a visible state, it should be regarded as
+                // visible, so the caller can know the next activity should be resumed.
+                hasVisibleActivities |= rootTask.handleAppDied(this);
             }
             r.handleAppDied();
         }
diff --git a/services/tests/wmtests/src/com/android/server/wm/ActivityTaskManagerServiceTests.java b/services/tests/wmtests/src/com/android/server/wm/ActivityTaskManagerServiceTests.java
index 2e988af296381..567610018fc10 100644
--- a/services/tests/wmtests/src/com/android/server/wm/ActivityTaskManagerServiceTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/ActivityTaskManagerServiceTests.java
@@ -225,5 +225,27 @@ public class ActivityTaskManagerServiceTests extends WindowTestsBase {
 
         mockSession.finishMocking();
     }
+
+    @Test
+    public void testResumeNextActivityOnCrashedAppDied() {
+        mSupervisor.beginDeferResume();
+        final ActivityRecord homeActivity = new ActivityBuilder(mAtm)
+                .setTask(mRootWindowContainer.getDefaultTaskDisplayArea().getOrCreateRootHomeTask())
+                .build();
+        final ActivityRecord activity = new ActivityBuilder(mAtm).setCreateTask(true).build();
+        mSupervisor.endDeferResume();
+        // Assume the activity is finishing and hidden because it was crashed.
+        activity.finishing = true;
+        activity.mVisibleRequested = false;
+        activity.setVisible(false);
+        activity.getRootTask().mPausingActivity = activity;
+        homeActivity.setState(Task.ActivityState.PAUSED, "test");
+
+        // Even the visibility states are invisible, the next activity should be resumed because
+        // the crashed activity was pausing.
+        mAtm.mInternal.handleAppDied(activity.app, false /* restarting */,
+                null /* finishInstrumentationCallback */);
+        assertEquals(Task.ActivityState.RESUMED, homeActivity.getState());
+    }
 }