Revise layer, extension and feature setup for Vulkan

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 13 matching lines @@
 class GrNonInstancedMesh;
 
 class GrVkBufferImpl;
 class GrVkCommandBuffer;
 class GrVkPipeline;
 class GrVkPipelineState;
 class GrVkRenderPass;
 class GrVkTexture;
 struct GrVkInterface;
 
-#ifdef SK_DEBUG
-#define ENABLE_VK_LAYERS
-#endif
-
 class GrVkGpu : public GrGpu {
 public:
     static GrGpu* Create(GrBackendContext backendContext, const GrContextOptions& options,
                          GrContext* context);
 
     ~GrVkGpu() override;
 
     const GrVkInterface* vkInterface() const { return fBackendContext->fInterface; }
     const GrVkCaps& vkCaps() const { return *fVkCaps; }
 
@@ skipping 187 matching lines @@
 
     // Shaderc compiler used for compiling glsl in spirv. We only want to create the compiler once
     // since there is significant overhead to the first compile of any compiler.
     shaderc_compiler_t fCompiler;
 
 
     typedef GrGpu INHERITED;
 };
 
 #endif