Animate windows when minimizing from and restoring to dock

BUG=264024
TEST=visual

Review URL: https://chromiumcodereview.appspot.com/24053006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@224178 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/ash/root_window_controller.cc b/ash/root_window_controller.cc
index 51fc711c..7c7909aa 100644
--- a/ash/root_window_controller.cc
+++ b/ash/root_window_controller.cc
@@ -693,6 +693,7 @@
       kShellWindowId_DockedContainer,
       "DockedContainer",
       non_lock_screen_containers);
+  views::corewm::SetChildWindowVisibilityChangesAnimated(docked_container);
   SetUsesScreenCoordinates(docked_container);
 
   aura::Window* panel_container = CreateContainer(