Add stub for new method to GrVkGpu

src/gpu/vk/GrVkGpu.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrVkGpu_DEFINED
 #define GrVkGpu_DEFINED
 
@@ skipping 119 matching lines @@
     GrTexture* onCreateCompressedTexture(const GrSurfaceDesc& desc, GrGpuResource::LifeCycle,
                                          const void* srcData) override {
         SkDebugf("onCreateCompressedTexture not yet implemented for Vulkan\n");
         return NULL;
     }
 
     GrTexture* onWrapBackendTexture(const GrBackendTextureDesc&, GrWrapOwnership) override;
 
     GrRenderTarget* onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&,
                                               GrWrapOwnership) override;
+    GrRenderTarget* onWrapBackendTextureAsRenderTarget(const GrBackendTextureDesc&,
+                                                       GrWrapOwnership) override {
+        SkDebugf("onWrapBackendTextureAsRenderTarget not yet implemented for Vulkan\n");
+        return NULL;
+    }
 
     GrVertexBuffer* onCreateVertexBuffer(size_t size, bool dynamic) override;
     GrIndexBuffer* onCreateIndexBuffer(size_t size, bool dynamic) override;
     GrTransferBuffer* onCreateTransferBuffer(size_t size, TransferType type) override;
 
     void onClear(GrRenderTarget*, const SkIRect& rect, GrColor color) override;
 
     void onClearStencilClip(GrRenderTarget*, const SkIRect& rect, bool insideClip) override {
         SkDebugf("onClearStencilClip not yet implemented for Vulkan\n");
     }
@@ skipping 61 matching lines @@
     shaderc_compiler_t fCompiler;
 
     // This is only for our current testing and building. The client should be holding on to the
     // VkInstance.
     VkInstance                        fVkInstance;
 
     typedef GrGpu INHERITED;
 };
 
 #endif