[ozone] Add stub async swap buffers implementation to ozone surfaceless.

ui/ozone/platform/egltest/ozone_platform_egltest.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 "ui/ozone/platform/egltest/ozone_platform_egltest.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/files/file_path.h"
@@ skipping 191 matching lines @@
   }
   ~SurfaceOzoneEgltest() {
     bool ret = eglplatform_shim_->ShimReleaseNativeWindow(native_window_);
     DCHECK(ret);
   }
 
   intptr_t GetNativeWindow() override { return native_window_; }
 
   bool OnSwapBuffers() override { return true; }
 
+  bool OnSwapBuffersAsync(const SwapCompletionCallback& callback) override {
+    callback.Run();
+    return true;
+  }
+
   bool ResizeNativeWindow(const gfx::Size& viewport_size) override {
     return true;
   }
 
   scoped_ptr<gfx::VSyncProvider> CreateVSyncProvider() override {
     return scoped_ptr<gfx::VSyncProvider>();
   }
 
  private:
   LibeglplatformShimLoader* eglplatform_shim_;
@@ skipping 163 matching lines @@
 
 }  // namespace
 
 OzonePlatform* CreateOzonePlatformEgltest() {
   OzonePlatformEgltest* platform = new OzonePlatformEgltest;
   platform->Initialize();
   return platform;
 }
 
 }  // namespace ui