views/mus: Set-up transient windows correctly.

components/mus/public/cpp/lib/window.cc

Index: components/mus/public/cpp/lib/window.cc
diff --git a/components/mus/public/cpp/lib/window.cc b/components/mus/public/cpp/lib/window.cc
index 46291b0a68092a0327e81f0c5acdde3fc2355275..94d598b9ca72fcda06a33977fb3fdc0ea6bc1e28 100644
--- a/components/mus/public/cpp/lib/window.cc
+++ b/components/mus/public/cpp/lib/window.cc
@@ -778,6 +778,8 @@ bool Window::ReorderImpl(Window* window,
   DCHECK(relative);
   DCHECK_NE(window, relative);
   DCHECK_EQ(window->parent(), relative->parent());
+  if (!window->parent())
+    return false;

[sadrul, 2016/01/11 21:37:34]

There is probably a bug that the WS sends reorder notifications for roots? I am
looking into it.

[sadrul, 2016/01/12 21:50:48]

Put up https://codereview.chromium.org/1580193002/ for this issue.

 
   if (!AdjustStackingForTransientWindows(&window, &relative, &direction,
                                          window->stacking_target_))