Add offset to memory allocations

src/gpu/vk/GrVkBuffer.h

Index: src/gpu/vk/GrVkBuffer.h
diff --git a/src/gpu/vk/GrVkBuffer.h b/src/gpu/vk/GrVkBuffer.h
index 141b2a378f3e6fed4a10ca652257ac0ccdcfc457..f7d43c796d592b7ca317afefe82506da71170859 100644
--- a/src/gpu/vk/GrVkBuffer.h
+++ b/src/gpu/vk/GrVkBuffer.h
@@ -10,6 +10,7 @@
 
 #include "GrVkResource.h"
 #include "vk/GrVkDefines.h"
+#include "vk/GrVkTypes.h"
 
 class GrVkGpu;
 
@@ -24,8 +25,8 @@ public:
         SkASSERT(!fResource);
     }
 
-    VkBuffer       buffer() const { return fResource->fBuffer; }
-    VkDeviceMemory 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; }
 
@@ -53,10 +54,12 @@ protected:
 
     class Resource : public GrVkResource {
     public:
-        Resource(VkBuffer buf, VkDeviceMemory alloc) : INHERITED(), fBuffer(buf), fAlloc(alloc) {}
+        Resource(VkBuffer buf, const GrVkAlloc& alloc) 
+            : INHERITED(), fBuffer(buf), fAlloc(alloc) {}
+
+        VkBuffer  fBuffer;
+        GrVkAlloc fAlloc;
 
-        VkBuffer fBuffer;
-        VkDeviceMemory fAlloc;
     private:
         void freeGPUData(const GrVkGpu* gpu) const;