Attempt 2 at: Fixes crash that occured because NativeViewHostAura::Detach was not

ui/views/widget/native_widget_aura.cc

 // Copyright (c) 2012 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/views/widget/native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/string_util.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/aura/client/activation_change_observer.h"
@@ skipping 528 matching lines @@
     // regardless of show state.
     SetInitialFocus();
   }
 }
 
 bool NativeWidgetAura::IsVisible() const {
   return window_->IsVisible();
 }
 
 void NativeWidgetAura::Activate() {
-  aura::client::GetActivationClient(window_->GetRootWindow())->ActivateWindow(
-      window_);
+  // We don't necessarily have a root window yet. This can happen with
+  // constrained windows.
+  if (window_->GetRootWindow())
+    aura::client::GetActivationClient(window_->GetRootWindow())->ActivateWindow(
+        window_);
 }
 
 void NativeWidgetAura::Deactivate() {
   aura::client::GetActivationClient(window_->GetRootWindow())->DeactivateWindow(
       window_);
 }
 
 bool NativeWidgetAura::IsActive() const {
   return aura::client::GetActivationClient(window_->GetRootWindow())->
       GetActiveWindow() == window_;
@@ skipping 434 matching lines @@
   return top_level_native_widget;
 }
 
 // static
 void NativeWidgetPrivate::GetAllChildWidgets(gfx::NativeView native_view,
                                              Widget::Widgets* children) {
   {
     // Code expects widget for |native_view| to be added to |children|.
     NativeWidgetAura* native_widget = static_cast<NativeWidgetAura*>(
         GetNativeWidgetForNativeView(native_view));
-    if (native_widget->GetWidget())
+    if (native_widget && native_widget->GetWidget())
       children->insert(native_widget->GetWidget());
   }
 
   const aura::Window::Windows& child_windows = native_view->children();
   for (aura::Window::Windows::const_iterator i = child_windows.begin();
        i != child_windows.end(); ++i) {
     NativeWidgetAura* native_widget =
         static_cast<NativeWidgetAura*>(GetNativeWidgetForNativeView(*i));
     if (native_widget)
       children->insert(native_widget->GetWidget());
@@ skipping 33 matching lines @@
   return aura::Env::GetInstance()->is_mouse_button_down();
 }
 
 // static
 bool NativeWidgetPrivate::IsTouchDown() {
   return aura::Env::GetInstance()->is_touch_down();
 }
 
 }  // namespace internal
 }  // namespace views