Fixes bug where client area would not get set correctly

ui/views/mus/native_widget_mus.cc

 // Copyright 2015 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/mus/native_widget_mus.h"
 
 #include "base/macros.h"
 #include "base/thread_task_runner_handle.h"
 #include "components/mus/public/cpp/property_type_converters.h"
 #include "components/mus/public/cpp/window.h"
@@ skipping 291 matching lines @@
   content_->Show();
   content_->SetTransparent(true);
   content_->SetFillsBoundsCompletely(false);
 
   window_tree_host_->window()->AddChild(content_);
   // TODO(beng): much else, see [Desktop]NativeWidgetAura.
 
   native_widget_delegate_->OnNativeWidgetCreated(false);
 }
 
+void NativeWidgetMus::OnWidgetInitDone() {
+  // The client area is calculated from the NonClientView. During
+  // InitNativeWidget() the NonClientView has not been created. When this
+  // function is called the NonClientView has been created, so that we can
+  // correctly calculate the client area and push it to the mus::Window.
+  UpdateClientArea();
+}
+
 bool NativeWidgetMus::ShouldUseNativeFrame() const {
   // NOTIMPLEMENTED();
   return false;
 }
 
 bool NativeWidgetMus::ShouldWindowContentsBeTransparent() const {
   // NOTIMPLEMENTED();
   return true;
 }
 
@@ skipping 480 matching lines @@
 
 void NativeWidgetMus::OnGestureEvent(ui::GestureEvent* event) {
   native_widget_delegate_->OnGestureEvent(event);
 }
 
 void NativeWidgetMus::OnHostCloseRequested(const aura::WindowTreeHost* host) {
   GetWidget()->Close();
 }
 
 }  // namespace views