aura-mus: wire up drag and drop.

ui/aura/mus/window_port_mus.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 "ui/aura/mus/window_port_mus.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/transient_window_client.h"
 #include "ui/aura/mus/client_surface_embedder.h"
@@ skipping 53 matching lines @@
 
   window_tree_client_->SetPredefinedCursor(this, predefined_cursor_, cursor_id);
   predefined_cursor_ = cursor_id;
 }
 
 void WindowPortMus::SetEventTargetingPolicy(
     ui::mojom::EventTargetingPolicy policy) {
   window_tree_client_->SetEventTargetingPolicy(this, policy);
 }
 
+void WindowPortMus::SetCanAcceptDrops(bool can_accept_drops) {
+  window_tree_client_->SetCanAcceptDrops(this, can_accept_drops);
+}
+
 void WindowPortMus::Embed(
     ui::mojom::WindowTreeClientPtr client,
     uint32_t flags,
     const ui::mojom::WindowTree::EmbedCallback& callback) {
   window_tree_client_->Embed(window_, std::move(client), flags, callback);
 }
 
 std::unique_ptr<ui::WindowCompositorFrameSink>
 WindowPortMus::RequestCompositorFrameSink(
     scoped_refptr<cc::ContextProvider> context_provider,
@@ skipping 358 matching lines @@
       GetPropertyConverter()->GetTransportNameForPropertyKey(key);
   // TODO(sky): investigate to see if we need to compare data. In particular do
   // we ever have a case where changing a property cascades into changing the
   // same property?
   if (!RemoveChangeByTypeAndData(ServerChangeType::PROPERTY, change_data))
     window_tree_client_->OnWindowMusPropertyChanged(this, key, old_value,
                                                     std::move(data));
 }
 
 }  // namespace aura