Add shoftcut (ctrl-f6) to toggle split view

athena/wm/split_view_controller.cc

Index: athena/wm/split_view_controller.cc
diff --git a/athena/wm/split_view_controller.cc b/athena/wm/split_view_controller.cc
index 232908994061e8095463a1847ce018e492d8c5b4..cf39f2e0c60d44af99ccb6f571a4192a13640a48 100644
--- a/athena/wm/split_view_controller.cc
+++ b/athena/wm/split_view_controller.cc
@@ -163,6 +163,9 @@ void SplitViewController::SetWindowTransform(aura::Window* window,
 }
 
 void SplitViewController::OnAnimationCompleted(aura::Window* window) {
+  // Animation can be cancelled when deactivated.
+  if (left_window_ == NULL)
+    return;
   DCHECK(window == left_window_ || window == right_window_);
   if (state_ == ACTIVE) {
     gfx::Rect window_bounds = gfx::Rect(container_->bounds().size());