Don't allow pinned activities to request visible behind

Also, release visible behind when pinning a visible behind activity.

Bug: 28042883
Change-Id: I1162d7639626f669f648ff82f5c367cb7b3fe6e6

1 files changed, 8 insertions, 0 deletions

diff --git a/core/java/android/app/ActivityManager.java b/core/java/android/app/ActivityManager.java
index 631a1293cdc0..424d3557a5aa 100644
--- a/core/java/android/app/ActivityManager.java
+++ b/core/java/android/app/ActivityManager.java
@@ -675,6 +675,14 @@ public class ActivityManager {
             return isStaticStack(stackId) || stackId == PINNED_STACK_ID
                     || stackId == FREEFORM_WORKSPACE_STACK_ID || stackId == DOCKED_STACK_ID;
         }
+
+        /**
+         * Returns true if activities contained in this stack can request visible behind by
+         * calling {@link Activity#requestVisibleBehind}.
+         */
+        public static boolean activitiesCanRequestVisibleBehind(int stackId) {
+            return stackId == FULLSCREEN_WORKSPACE_STACK_ID;
+        }
     }
 
     /**