Added the Vulkan Context Provider implementation.

cc/output/vulkan_context_provider.h

 // Copyright (c) 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.
 
 #ifndef CC_OUTPUT_VULKAN_CONTEXT_PROVIDER_H_
 #define CC_OUTPUT_VULKAN_CONTEXT_PROVIDER_H_
 
 #include "base/memory/ref_counted.h"
 
 namespace gpu {
 class VulkanDeviceQueue;
 }
 
 namespace cc {
 
 // The VulkanContextProvider groups sharing of vulkan objects synchronously.
 class VulkanContextProvider
     : public base::RefCountedThreadSafe<VulkanContextProvider> {
  public:
   virtual gpu::VulkanDeviceQueue* GetDeviceQueue() = 0;
 
+  virtual void SwapBuffers() = 0;
+
  protected:
   friend class base::RefCountedThreadSafe<VulkanContextProvider>;
   virtual ~VulkanContextProvider() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_VULKAN_CONTEXT_PROVIDER_H_