Add automatic generation of mipmaps to Vulkan

src/gpu/vk/GrVkTexture.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 GrVkTexture_DEFINED
 #define GrVkTexture_DEFINED
 
@@ skipping 15 matching lines @@
                                              VkFormat, const GrVkTextureInfo*);
 
     ~GrVkTexture() override;
 
     GrBackendObject getTextureHandle() const override;
 
     void textureParamsModified() override {}
 
     const GrVkImageView* textureView() const { return fTextureView; }
 
+    bool reallocForMipmap(const GrVkGpu* gpu);
+
 protected:
     GrVkTexture(GrVkGpu*, const GrSurfaceDesc&,
                 const GrVkImage::Resource*, const GrVkImageView* imageView);
 
     template<typename ResourceType>
     static GrVkTexture* Create(GrVkGpu*, ResourceType, const GrSurfaceDesc&, VkFormat,
                                const GrVkImage::Resource* texImpl);
 
     GrVkGpu* getVkGpu() const;
 
     void onAbandon() override;
     void onRelease() override;
 
 private:
     enum Wrapped { kWrapped };
     GrVkTexture(GrVkGpu*, SkBudgeted, const GrSurfaceDesc&,
                 const GrVkImage::Resource*, const GrVkImageView* imageView);
     GrVkTexture(GrVkGpu*, Wrapped, const GrSurfaceDesc&,
                 const GrVkImage::Resource*, const GrVkImageView* imageView);
 
 
     const GrVkImageView* fTextureView;
 
     typedef GrTexture INHERITED;
 };
 
 #endif