Introduce Display Compositor mojo interface. Use InProcessContextProvider.

services/ui/ws/window_tree.cc

 // Copyright 2014 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 "services/ui/ws/window_tree.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 1355 matching lines @@
     cc::mojom::MojoCompositorFrameSinkRequest compositor_frame_sink,
     cc::mojom::MojoCompositorFrameSinkClientPtr client) {
   ServerWindow* window =
       GetWindowByClientId(ClientWindowId(transport_window_id));
   const bool success =
       window && access_policy_->CanSetWindowCompositorFrameSink(window, type);
   if (!success) {
     DVLOG(1) << "request to AttachCompositorFrameSink failed";
     return;
   }
-  window->CreateCompositorFrameSink(type, gfx::kNullAcceleratedWidget, nullptr,
-                                    nullptr, std::move(compositor_frame_sink),
+  window->CreateCompositorFrameSink(type, gfx::kNullAcceleratedWidget,
+                                    std::move(compositor_frame_sink),
                                     std::move(client));
 }
 
 void WindowTree::SetWindowTextInputState(Id transport_window_id,
                                          mojo::TextInputStatePtr state) {
   ServerWindow* window =
       GetWindowByClientId(ClientWindowId(transport_window_id));
   bool success = window && access_policy_->CanSetWindowTextInputState(window);
   if (success)
     window->SetTextInputState(state.To<ui::TextInputState>());
@@ skipping 557 matching lines @@
   client()->OnCompleteDrop(client_window_id.id, event_flags, cursor_offset,
                            effect_bitmask, callback);
 }
 
 void WindowTree::PerformOnDragDropDone() {
   client()->OnDragDropDone();
 }
 
 }  // namespace ws
 }  // namespace ui