Don't create new descriptor set for vulkan uniforms every draw

src/gpu/vk/GrVkBuffer.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 GrVkBuffer_DEFINED
 #define GrVkBuffer_DEFINED
 
@@ skipping 55 matching lines @@
     // convenience routine for raw buffer creation
     static const Resource* Create(const GrVkGpu* gpu,
                                   const Desc& descriptor);
 
     GrVkBuffer(const Desc& desc, const GrVkBuffer::Resource* resource)
         : fDesc(desc), fResource(resource), fMapPtr(nullptr) {
     }
 
     void* vkMap(const GrVkGpu* gpu);
     void vkUnmap(const GrVkGpu* gpu);
-    bool vkUpdateData(const GrVkGpu* gpu, const void* src, size_t srcSizeInBytes);
+    // If the caller passes in a non null createdNewBuffer, this function will set the bool to true
+    // if it creates a new VkBuffer to upload the data to.
+    bool vkUpdateData(const GrVkGpu* gpu, const void* src, size_t srcSizeInBytes,
+                      bool* createdNewBuffer = nullptr);
 
     void vkAbandon();
     void vkRelease(const GrVkGpu* gpu);
 
 private:
     void validate() const;
     bool vkIsMapped() const;
 
     Desc                    fDesc;
     const Resource*         fResource;
     void*                   fMapPtr;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif