Fixes bug in handling restacking because of transients

ui/wm/core/transient_window_manager.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/wm/core/transient_window_manager.h"
 
 #include <algorithm>
 #include <functional>
 
 #include "base/auto_reset.h"
@@ skipping 119 matching lines @@
   // |window_|. The existing stacking order is preserved by iterating backwards
   // and always stacking on top.
   Window::Windows children(parent->children());
   for (Window::Windows::reverse_iterator it = children.rbegin();
        it != children.rend(); ++it) {
     if ((*it) != window_ && HasTransientAncestor(*it, window_)) {
       TransientWindowManager* descendant_manager = Get(*it);
       base::AutoReset<Window*> resetter(
           &descendant_manager->stacking_target_,
           window_);
+      for (aura::client::TransientWindowClientObserver& observer :
+           TransientWindowController::Get()->observers_) {
+        observer.OnWillRestackTransientChildAbove(window_, *it);
+      }
       parent->StackChildAbove((*it), window_);
+      for (aura::client::TransientWindowClientObserver& observer :
+           TransientWindowController::Get()->observers_) {
+        observer.OnDidRestackTransientChildAbove(window_, *it);
+      }
     }
   }
 }
 
 void TransientWindowManager::OnWindowParentChanged(aura::Window* window,
                                                    aura::Window* parent) {
   DCHECK_EQ(window_, window);
   // Stack |window| properly if it is transient child of a sibling.
   Window* transient_parent = wm::GetTransientParent(window);
   if (transient_parent && transient_parent->parent() == parent) {
@@ skipping 78 matching lines @@
   // Destroy transient children, only after we've removed ourselves from our
   // parent, as destroying an active transient child may otherwise attempt to
   // refocus us.
   Windows transient_children(transient_children_);
   for (auto* child : transient_children)
     delete child;
   DCHECK(transient_children_.empty());
 }
 
 }  // namespace wm