Animate pinned stack resizing.

This introduces animating of stack bounds within window manager
module. It also uses this type of animation when moving an activity from
fullscreen stack to pinned stack.

Bug: 25672053
Change-Id: I75914a685d10021f8a7535b47ef12b6920b3fd5e
diff --git a/services/core/java/com/android/server/wm/AppTransition.java b/services/core/java/com/android/server/wm/AppTransition.java
index 552af03..43a17c9 100644
--- a/services/core/java/com/android/server/wm/AppTransition.java
+++ b/services/core/java/com/android/server/wm/AppTransition.java
@@ -134,7 +134,7 @@
     /** Fraction of animation at which the recents thumbnail becomes completely transparent */
     private static final float RECENTS_THUMBNAIL_FADEOUT_FRACTION = 0.5f;
 
-    private static final int DEFAULT_APP_TRANSITION_DURATION = 336;
+    static final int DEFAULT_APP_TRANSITION_DURATION = 336;
     private static final int THUMBNAIL_APP_TRANSITION_DURATION = 336;
     private static final int THUMBNAIL_APP_TRANSITION_ALPHA_DURATION = 336;
     private static final long APP_TRANSITION_TIMEOUT_MS = 5000;