Add offsets to GrVkBuffer.

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
 
 #include "GrVkResource.h"
 #include "vk/GrVkDefines.h"
 #include "vk/GrVkTypes.h"
 
 class GrVkGpu;
 
 /**
  * This class serves as the base of GrVk*Buffer classes. It was written to avoid code
  * duplication in those classes.
  */
 class GrVkBuffer : public SkNoncopyable {
 public:
     ~GrVkBuffer() {
         // either release or abandon should have been called by the owner of this object.
         SkASSERT(!fResource);
     }
 
-    VkBuffer buffer() const { return fResource->fBuffer; }
-    const GrVkAlloc& alloc() const { return fResource->fAlloc; }
+    VkBuffer            buffer() const { return fResource->fBuffer; }
+    const GrVkAlloc&    alloc() const { return fResource->fAlloc; }
     const GrVkResource* resource() const { return fResource; }
-    size_t         size() const { return fDesc.fSizeInBytes; }
+    size_t              size() const { return fDesc.fSizeInBytes; }
+    VkDeviceSize        offset() const { return fOffset;  }
 
     void addMemoryBarrier(const GrVkGpu* gpu,
                           VkAccessFlags srcAccessMask,
                           VkAccessFlags dstAccessMask,
                           VkPipelineStageFlags srcStageMask,
                           VkPipelineStageFlags dstStageMask,
                           bool byRegion) const;
 
     enum Type {
         kVertex_Type,
@@ skipping 28 matching lines @@
         void freeGPUData(const GrVkGpu* gpu) const;
 
         typedef GrVkResource INHERITED;
     };
 
     // 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) {
+        : fDesc(desc), fResource(resource), fOffset(0), fMapPtr(nullptr) {
     }
 
     void* vkMap(const GrVkGpu* gpu);
     void vkUnmap(GrVkGpu* gpu);
     // 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(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;
+    VkDeviceSize            fOffset;
     void*                   fMapPtr;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif