Consolidate GPU buffer implementations

src/gpu/vk/GrVkGpu.cpp

Index: src/gpu/vk/GrVkGpu.cpp
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index 21e4ee358d57c3b04411452466f0c29e6a9afe15..5796f11d51562d1d311c9a969321798ff0c52fc5 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -171,18 +171,26 @@ void GrVkGpu::submitCommandBuffer(SyncQueue sync) {
 }
 
 ///////////////////////////////////////////////////////////////////////////////
-GrVertexBuffer* GrVkGpu::onCreateVertexBuffer(size_t size, bool dynamic) {
-    return GrVkVertexBuffer::Create(this, size, dynamic);
-}
-
-GrIndexBuffer* GrVkGpu::onCreateIndexBuffer(size_t size, bool dynamic) {
-    return GrVkIndexBuffer::Create(this, size, dynamic);
-}
-
-GrTransferBuffer* GrVkGpu::onCreateTransferBuffer(size_t size, TransferType type) {
-    GrVkBuffer::Type bufferType = kCpuToGpu_TransferType ? GrVkBuffer::kCopyRead_Type 
-                                                         : GrVkBuffer::kCopyWrite_Type;
-    return GrVkTransferBuffer::Create(this, size, bufferType);
+GrBuffer* GrVkGpu::onCreateBuffer(GrBufferType type, size_t size, GrAccessPattern accessPattern) {
+    switch (type) {
+        case kVertex_GrBufferType:
+            SkASSERT(kDynamic_GrAccessPattern == accessPattern ||
+                     kStatic_GrAccessPattern == accessPattern);
+            return GrVkVertexBuffer::Create(this, size, kDynamic_GrAccessPattern == accessPattern);
+        case kIndex_GrBufferType:
+            SkASSERT(kDynamic_GrAccessPattern == accessPattern ||
+                     kStatic_GrAccessPattern == accessPattern);
+            return GrVkIndexBuffer::Create(this, size, kDynamic_GrAccessPattern == accessPattern);
+        case kXferCpuToGpu_GrBufferType:
+            SkASSERT(kStream_GrAccessPattern == accessPattern);
+            return GrVkTransferBuffer::Create(this, size, GrVkBuffer::kCopyRead_Type);
+        case kXferGpuToCpu_GrBufferType:
+            SkASSERT(kStream_GrAccessPattern == accessPattern);
+            return GrVkTransferBuffer::Create(this, size, GrVkBuffer::kCopyWrite_Type);
+        default:
+            SkFAIL("Unknown buffer type.");
+            return nullptr;
+    }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -1217,8 +1225,9 @@ bool GrVkGpu::onReadPixels(GrSurface* surface,
                         false);
 
     GrVkTransferBuffer* transferBuffer = 
-        reinterpret_cast<GrVkTransferBuffer*>(this->createTransferBuffer(rowBytes * height, 
-                                                                         kGpuToCpu_TransferType));
+        static_cast<GrVkTransferBuffer*>(this->createBuffer(kXferGpuToCpu_GrBufferType,
+                                                            rowBytes * height,
+                                                            kStream_GrAccessPattern));
 
     bool flipY = kBottomLeft_GrSurfaceOrigin == surface->origin();
     VkOffset3D offset = {