Add transfer buffer support.

src/gpu/GrGpu.cpp

Index: src/gpu/GrGpu.cpp
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index 439fe1b70fa9779c9d3e5b0325aebe85d8f7156a..a9b283f3cec8a836a743a2078bd5d6a95da31ada 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -20,6 +20,7 @@
 #include "GrRenderTargetPriv.h"
 #include "GrStencilAttachment.h"
 #include "GrSurfacePriv.h"
+#include "GrTransferBuffer.h"
 #include "GrVertexBuffer.h"
 #include "GrVertices.h"
 
@@ -197,6 +198,12 @@ GrIndexBuffer* GrGpu::createIndexBuffer(size_t size, bool dynamic) {
     return ib;
 }
 
+GrTransferBuffer* GrGpu::createTransferBuffer(size_t size, TransferType type) {
+    this->handleDirtyContext();
+    GrTransferBuffer* tb = this->onCreateTransferBuffer(size, type);
+    return tb;
+}
+
 void GrGpu::clear(const SkIRect& rect,
                   GrColor color,
                   GrRenderTarget* renderTarget) {