Auto resuming app switch for visible apps

Or unable to launch activities from apps, even the app
has visible windows, like bubbles.

Bug: 208198575
Test: start activity from bubble
Test: atest BackgroundActivityLaunchTest
Change-Id: I0d9b0b16a437ddda1e0da9be930f3418d5751ce5

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

@@ -72,6 +72,8 @@ import static com.android.server.wm.ActivityTaskManagerDebugConfig.POSTFIX_USER_
 import static com.android.server.wm.ActivityTaskManagerDebugConfig.TAG_ATM;
 import static com.android.server.wm.ActivityTaskManagerDebugConfig.TAG_WITH_CLASS_NAME;
 import static com.android.server.wm.ActivityTaskManagerService.ANIMATE;
+import static com.android.server.wm.ActivityTaskManagerService.APP_SWITCH_ALLOW;
+import static com.android.server.wm.ActivityTaskManagerService.APP_SWITCH_FG_ONLY;
 import static com.android.server.wm.ActivityTaskSupervisor.DEFER_RESUME;
 import static com.android.server.wm.ActivityTaskSupervisor.ON_TOP;
 import static com.android.server.wm.ActivityTaskSupervisor.PRESERVE_WINDOWS;
@@ -1275,7 +1277,10 @@ class ActivityStarter {
 
         // This is used to block background activity launch even if the app is still
         // visible to user after user clicking home button.
-        final boolean appSwitchAllowed = mService.getBalAppSwitchesAllowed();
+        final int appSwitchState = mService.getBalAppSwitchesState();
+        final boolean appSwitchAllowed = appSwitchState == APP_SWITCH_ALLOW;
+        final boolean appSwitchAllowedOrFg =
+                appSwitchState == APP_SWITCH_ALLOW || appSwitchState == APP_SWITCH_FG_ONLY;
 
         // don't abort if the callingUid has a visible window or is a persistent system process
         final int callingUidProcState = mService.mActiveUids.getUidState(callingUid);
@@ -1288,7 +1293,7 @@ class ActivityStarter {
 
         // Normal apps with visible app window will be allowed to start activity if app switching
         // is allowed, or apps like live wallpaper with non app visible window will be allowed.
-        if (((appSwitchAllowed || mService.mActiveUids.hasNonAppVisibleWindow(callingUid))
+        if (((appSwitchAllowedOrFg || mService.mActiveUids.hasNonAppVisibleWindow(callingUid))
                 && callingUidHasAnyVisibleWindow)
                 || isCallingUidPersistentSystemProcess) {
             if (DEBUG_ACTIVITY_STARTS) {
@@ -1426,7 +1431,7 @@ class ActivityStarter {
         // anything that has fallen through would currently be aborted
         Slog.w(TAG, "Background activity start [callingPackage: " + callingPackage
                 + "; callingUid: " + callingUid
-                + "; appSwitchAllowed: " + appSwitchAllowed
+                + "; appSwitchState: " + appSwitchState
                 + "; isCallingUidForeground: " + isCallingUidForeground
                 + "; callingUidHasAnyVisibleWindow: " + callingUidHasAnyVisibleWindow
                 + "; callingUidProcState: " + DebugUtils.valueToString(ActivityManager.class,

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

@@ -504,7 +504,27 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
      * Whether normal application switches are allowed; a call to {@link #stopAppSwitches()
      * disables this.
      */
-    private volatile boolean mAppSwitchesAllowed = true;
+    private volatile int mAppSwitchesState = APP_SWITCH_ALLOW;
+
+    // The duration of resuming foreground app switch from disallow.
+    private static final long RESUME_FG_APP_SWITCH_MS = 500;
+
+    /** App switch is not allowed. */
+    static final int APP_SWITCH_DISALLOW = 0;
+
+    /** App switch is allowed only if the activity launch was requested by a foreground app. */
+    static final int APP_SWITCH_FG_ONLY = 1;
+
+    /** App switch is allowed. */
+    static final int APP_SWITCH_ALLOW = 2;
+
+    @IntDef({
+            APP_SWITCH_DISALLOW,
+            APP_SWITCH_FG_ONLY,
+            APP_SWITCH_ALLOW,
+    })
+    @Retention(RetentionPolicy.SOURCE)
+    @interface AppSwitchState {}
 
     /**
      * Last stop app switches time, apps finished before this time cannot start background activity
@@ -1247,7 +1267,7 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
             if (topFocusedRootTask != null && topFocusedRootTask.getTopResumedActivity() != null
                     && topFocusedRootTask.getTopResumedActivity().info.applicationInfo.uid
                     == Binder.getCallingUid()) {
-                mAppSwitchesAllowed = true;
+                mAppSwitchesState = APP_SWITCH_ALLOW;
             }
         }
         return pir.sendInner(0, fillInIntent, resolvedType, allowlistToken, null, null,
@@ -2158,8 +2178,8 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
     /**
      * Return true if app switching is allowed.
      */
-    boolean getBalAppSwitchesAllowed() {
+    @AppSwitchState int getBalAppSwitchesState() {
-        return mAppSwitchesAllowed;
+        return mAppSwitchesState;
     }
 
     /** Register an {@link AnrController} to control the ANR dialog behavior */
@@ -3680,8 +3700,10 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
     public void stopAppSwitches() {
         mAmInternal.enforceCallingPermission(STOP_APP_SWITCHES, "stopAppSwitches");
         synchronized (mGlobalLock) {
-            mAppSwitchesAllowed = false;
+            mAppSwitchesState = APP_SWITCH_DISALLOW;
             mLastStopAppSwitchesTime = SystemClock.uptimeMillis();
+            mH.removeMessages(H.RESUME_FG_APP_SWITCH_MSG);
+            mH.sendEmptyMessageDelayed(H.RESUME_FG_APP_SWITCH_MSG, RESUME_FG_APP_SWITCH_MS);
         }
     }
 
@@ -3689,7 +3711,8 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
     public void resumeAppSwitches() {
         mAmInternal.enforceCallingPermission(STOP_APP_SWITCHES, "resumeAppSwitches");
         synchronized (mGlobalLock) {
-            mAppSwitchesAllowed = true;
+            mAppSwitchesState = APP_SWITCH_ALLOW;
+            mH.removeMessages(H.RESUME_FG_APP_SWITCH_MSG);
         }
     }
 
@@ -5170,6 +5193,7 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
         static final int REPORT_TIME_TRACKER_MSG = 1;
         static final int UPDATE_PROCESS_ANIMATING_STATE = 2;
         static final int END_POWER_MODE_UNKNOWN_VISIBILITY_MSG = 3;
+        static final int RESUME_FG_APP_SWITCH_MSG = 4;
 
         static final int FIRST_ACTIVITY_TASK_MSG = 100;
         static final int FIRST_SUPERVISOR_TASK_MSG = 200;
@@ -5207,6 +5231,14 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
                     }
                 }
                 break;
+                case RESUME_FG_APP_SWITCH_MSG: {
+                    synchronized (mGlobalLock) {
+                        if (mAppSwitchesState == APP_SWITCH_DISALLOW) {
+                            mAppSwitchesState = APP_SWITCH_FG_ONLY;
+                        }
+                    }
+                }
+                break;
             }
         }
     }

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

@@ -37,6 +37,7 @@ import static com.android.server.wm.ActivityTaskManagerDebugConfig.POSTFIX_CONFI
 import static com.android.server.wm.ActivityTaskManagerDebugConfig.POSTFIX_RELEASE;
 import static com.android.server.wm.ActivityTaskManagerDebugConfig.TAG_ATM;
 import static com.android.server.wm.ActivityTaskManagerDebugConfig.TAG_WITH_CLASS_NAME;
+import static com.android.server.wm.ActivityTaskManagerService.APP_SWITCH_ALLOW;
 import static com.android.server.wm.ActivityTaskManagerService.INSTRUMENTATION_KEY_DISPATCHING_TIMEOUT_MILLIS;
 import static com.android.server.wm.ActivityTaskManagerService.RELAUNCH_REASON_NONE;
 
@@ -512,7 +513,7 @@ public class WindowProcessController extends ConfigurationContainer<Configuratio
      */
     @HotPath(caller = HotPath.START_SERVICE)
     public boolean areBackgroundFgsStartsAllowed() {
-        return areBackgroundActivityStartsAllowed(mAtm.getBalAppSwitchesAllowed(),
+        return areBackgroundActivityStartsAllowed(mAtm.getBalAppSwitchesState() == APP_SWITCH_ALLOW,
                 true /* isCheckingForFgsStart */);
     }