MacViews: Ensure the RootView is in place before the first call to ReorderNativeViews

ui/views/widget/native_widget_mac.mm

 // 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/views/widget/native_widget_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
@@ skipping 100 matching lines @@
       initWithContentRect:content_rect
                 styleMask:style_mask
                   backing:NSBackingStoreBuffered
                     defer:YES]);
   [window setReleasedWhenClosed:NO];  // Owned by scoped_nsobject.
   bridge_->Init(window, params);
 
   delegate_->OnNativeWidgetCreated(true);
 
   bridge_->SetFocusManager(GetWidget()->GetFocusManager());
+
+  DCHECK(GetWidget()->GetRootView());
+  bridge_->SetRootView(GetWidget()->GetRootView());
 }
 
 NonClientFrameView* NativeWidgetMac::CreateNonClientFrameView() {
   return new NativeFrameView(GetWidget());
 }
 
 bool NativeWidgetMac::ShouldUseNativeFrame() const {
   return true;
 }
 
@@ skipping 465 matching lines @@
 }
 
 // static
 gfx::FontList NativeWidgetPrivate::GetWindowTitleFontList() {
   NOTIMPLEMENTED();
   return gfx::FontList();
 }
 
 }  // namespace internal
 }  // namespace views