Setup system in Vulkan to reuse VkDescriptorSet allocations.

src/gpu/vk/GrVkImage.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 GrVkImage_DEFINED
 #define GrVkImage_DEFINED
 
@@ skipping 92 matching lines @@
             fAlloc.fOffset = 0;
         }
 
         Resource(VkImage image, const GrVkAlloc& alloc, VkImageTiling tiling)
             : fImage(image), fAlloc(alloc), fImageTiling(tiling) {}
 
         ~Resource() override {}
 
 #ifdef SK_TRACE_VK_RESOURCES
         void dumpInfo() const override {
-            SkDebugf("GrVkImage: %d (%d refs)\n", fImage, this->getRefCnt()); 
+            SkDebugf("GrVkImage: %d (%d refs)\n", fImage, this->getRefCnt());
         }
 #endif
     private:
         void freeGPUData(const GrVkGpu* gpu) const override;
 
         VkImage        fImage;
         GrVkAlloc      fAlloc;
         VkImageTiling  fImageTiling;
 
         typedef GrVkResource INHERITED;
     };
 
     // for wrapped textures
     class BorrowedResource : public Resource {
     public:
         BorrowedResource(VkImage image, const GrVkAlloc& alloc, VkImageTiling tiling)
             : Resource(image, alloc, tiling) {
         }
     private:
         void freeGPUData(const GrVkGpu* gpu) const override;
     };
 
     const Resource* fResource;
 
     friend class GrVkRenderTarget;
 };
 
 #endif