Allow a Views client to provide a default frameview for window widgets.

ui/views/widget/widget.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/widget.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/hit_test.h"
@@ skipping 732 matching lines @@
 }
 
 void Widget::UpdateFrameAfterFrameChange() {
   native_widget_->UpdateFrameAfterFrameChange();
 }
 
 NonClientFrameView* Widget::CreateNonClientFrameView() {
   NonClientFrameView* frame_view = widget_delegate_->CreateNonClientFrameView();
   if (!frame_view)
     frame_view = native_widget_->CreateNonClientFrameView();
+  if (!frame_view && ViewsDelegate::views_delegate) {
+    frame_view =
+        ViewsDelegate::views_delegate->CreateDefaultNonClientFrameView(this);
+  }
   return frame_view ? frame_view : new CustomFrameView(this);
 }
 
 bool Widget::ShouldUseNativeFrame() const {
   if (frame_type_ != FRAME_TYPE_DEFAULT)
     return frame_type_ == FRAME_TYPE_FORCE_NATIVE;
   return native_widget_->ShouldUseNativeFrame();
 }
 
 void Widget::DebugToggleFrameType() {
@@ skipping 464 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views