Also calculate minimal task size when window manager is set.

Bug: 21409825
Change-Id: If0dbbd8976607a5c0db13f608af01f21c41f45ed
diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index 33f9f6b..2a36230 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -437,6 +437,7 @@
                     throw new IllegalStateException("Default Display does not exist");
                 }
                 mActivityDisplays.put(displayId, activityDisplay);
+                calculateDefaultMinimalSizeOfResizeableTasks(activityDisplay);
             }
 
             createStackOnDisplay(HOME_STACK_ID, Display.DEFAULT_DISPLAY, true);