Add FLAG_IMMUTABLE to PendingIntent

PIs need a mutability flag on creation. See go/immutable-pendingintents for more context.

Change-Id: I7ac6a76fd501f36adddfd5bf85f0216a37fa9637
Test: TH
diff --git a/quickstep/src/com/android/quickstep/TouchInteractionService.java b/quickstep/src/com/android/quickstep/TouchInteractionService.java
index 1f7cec5..196cae7 100644
--- a/quickstep/src/com/android/quickstep/TouchInteractionService.java
+++ b/quickstep/src/com/android/quickstep/TouchInteractionService.java
@@ -360,7 +360,7 @@
                     getString(R.string.all_apps_label),
                     getString(R.string.all_apps_label),
                     PendingIntent.getActivity(this, SYSTEM_ACTION_ID_ALL_APPS, intent,
-                            PendingIntent.FLAG_UPDATE_CURRENT));
+                            PendingIntent.FLAG_UPDATE_CURRENT | PendingIntent.FLAG_IMMUTABLE));
             am.registerSystemAction(allAppsAction, SYSTEM_ACTION_ID_ALL_APPS);
         } else {
             am.unregisterSystemAction(SYSTEM_ACTION_ID_ALL_APPS);