Adds DesktopWindowTreeHostMus

ui/views/widget/desktop_aura/desktop_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/desktop_aura/desktop_native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/macros.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
@@ skipping 246 matching lines @@
   else
     CloseNow();
 }
 
 // static
 DesktopNativeWidgetAura* DesktopNativeWidgetAura::ForWindow(
     aura::Window* window) {
   return window->GetProperty(kDesktopNativeWidgetAuraKey);
 }
 
+void DesktopNativeWidgetAura::SetDesktopWindowTreeHost(
+    std::unique_ptr<DesktopWindowTreeHost> desktop_window_tree_host) {
+  DCHECK(!desktop_window_tree_host_);
+  desktop_window_tree_host_ = desktop_window_tree_host.get();
+  host_.reset(desktop_window_tree_host.release()->AsWindowTreeHost());
+}
+
 void DesktopNativeWidgetAura::OnHostClosed() {
   // Don't invoke Widget::OnNativeWidgetDestroying(), its done by
   // DesktopWindowTreeHost.
 
   // The WindowModalityController is at the front of the event pretarget
   // handler list. We destroy it first to preserve order symantics.
   if (window_modality_controller_)
     window_modality_controller_.reset();
 
   // Make sure we don't have capture. Otherwise CaptureController and
@@ skipping 118 matching lines @@
   }
   content_window_->SetType(GetAuraWindowTypeForWidgetType(params.type));
   content_window_->Init(params.layer_type);
   wm::SetShadowType(content_window_, wm::SHADOW_TYPE_NONE);
 
   content_window_container_ = new aura::Window(NULL);
   content_window_container_->Init(ui::LAYER_NOT_DRAWN);
   content_window_container_->Show();
   content_window_container_->AddChild(content_window_);
 
-  desktop_window_tree_host_ = params.desktop_window_tree_host ?
-      params.desktop_window_tree_host :
-      DesktopWindowTreeHost::Create(native_widget_delegate_, this);
-  host_.reset(desktop_window_tree_host_->AsWindowTreeHost());
+  if (!desktop_window_tree_host_) {
+    desktop_window_tree_host_ =
+        params.desktop_window_tree_host
+            ? params.desktop_window_tree_host
+            : DesktopWindowTreeHost::Create(native_widget_delegate_, this);
+    host_.reset(desktop_window_tree_host_->AsWindowTreeHost());
+  }
   desktop_window_tree_host_->Init(content_window_, params);
 
   host_->InitHost();
   host_->window()->AddChild(content_window_container_);
   host_->window()->SetProperty(kDesktopNativeWidgetAuraKey, this);
 
   host_->window()->AddObserver(new RootWindowDestructionObserver(this));
 
   // The WindowsModalityController event filter should be at the head of the
   // pre target handlers list. This ensures that it handles input events first
@@ skipping 37 matching lines @@
       new wm::FocusController(new DesktopFocusRules(content_window_));
   focus_client_.reset(focus_controller);
   aura::client::SetFocusClient(host_->window(), focus_controller);
   aura::client::SetActivationClient(host_->window(), focus_controller);
   host_->window()->AddPreTargetHandler(focus_controller);
 
   position_client_.reset(new DesktopScreenPositionClient(host_->window()));
 
   drag_drop_client_ = desktop_window_tree_host_->CreateDragDropClient(
       native_cursor_manager_);
-  aura::client::SetDragDropClient(host_->window(),
-                                  drag_drop_client_.get());
+  // Mus returns null from CreateDragDropClient().
+  if (drag_drop_client_)
+    aura::client::SetDragDropClient(host_->window(), drag_drop_client_.get());
 
   static_cast<aura::client::FocusClient*>(focus_client_.get())->
       FocusWindow(content_window_);
 
   OnHostResized(host());
 
   host_->AddObserver(this);
 
   window_parenting_client_.reset(
       new DesktopNativeWidgetAuraWindowParentingClient(host_->window()));
@@ skipping 702 matching lines @@
   if (cursor_reference_count_ == 0) {
     // We are the last DesktopNativeWidgetAura instance, and we are responsible
     // for cleaning up |cursor_manager_|.
     delete cursor_manager_;
     native_cursor_manager_ = NULL;
     cursor_manager_ = NULL;
   }
 }
 
 }  // namespace views