Introduce Display Compositor mojo interface. Use InProcessContextProvider.

services/ui/ws/test_server_window_delegate.h

Index: services/ui/ws/test_server_window_delegate.h
diff --git a/services/ui/ws/test_server_window_delegate.h b/services/ui/ws/test_server_window_delegate.h
index 7ab25be34f7307cde5b09928f7a363403d6c96e3..8feecc3dc79d478b531bdacabab7dca853ed321c 100644
--- a/services/ui/ws/test_server_window_delegate.h
+++ b/services/ui/ws/test_server_window_delegate.h
@@ -6,6 +6,7 @@
 #define SERVICES_UI_WS_TEST_SERVER_WINDOW_DELEGATE_H_
 
 #include "base/macros.h"
+#include "services/ui/surfaces/display_compositor.h"
 #include "services/ui/ws/server_window_delegate.h"
 
 namespace ui {
@@ -23,11 +24,11 @@ class TestServerWindowDelegate : public ServerWindowDelegate {
 
  private:
   // ServerWindowDelegate:
-  ui::DisplayCompositor* GetDisplayCompositor() override;
+  cc::mojom::DisplayCompositor* GetDisplayCompositor() override;
   ServerWindow* GetRootWindow(const ServerWindow* window) override;
 
   ServerWindow* root_window_;
-  scoped_refptr<ui::DisplayCompositor> display_compositor_;
+  std::unique_ptr<ui::DisplayCompositor> display_compositor_;
 
   DISALLOW_COPY_AND_ASSIGN(TestServerWindowDelegate);
 };