WidgetDelegateView is its own contents view.

mash/browser/browser.cc

 // Copyright 2016 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 "mash/browser/browser.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 557 matching lines @@
   ~UI() override {
     browser_->RemoveWindow(GetWidget());
   }
 
   void NavigateTo(const GURL& url) {
     selected_view()->NavigateToURL(url);
   }
 
  private:
   // Overridden from views::WidgetDelegate:
-  views::View* GetContentsView() override { return this; }
   base::string16 GetWindowTitle() const override {
     // TODO(beng): use resources.
     if (selected_view()->title().empty())
       return base::ASCIIToUTF16("Browser");
     base::string16 format = base::ASCIIToUTF16("%s - Browser");
     base::ReplaceFirstSubstringAfterOffset(&format, 0, base::ASCIIToUTF16("%s"),
                                            selected_view()->title());
     return format;
   }
   bool CanResize() const override { return true; }
@@ skipping 307 matching lines @@
   AddWindow(window);
 }
 
 void Browser::Create(const shell::Identity& remote_identity,
                      mojom::LaunchableRequest request) {
   bindings_.AddBinding(this, std::move(request));
 }
 
 }  // namespace browser
 }  // namespace mash