More framework support for TransferBuffers

src/gpu/gl/GrGLGpu.h

Index: src/gpu/gl/GrGLGpu.h
diff --git a/src/gpu/gl/GrGLGpu.h b/src/gpu/gl/GrGLGpu.h
index d802f08b75b236ce6a8820a82e50b7a565fbd97d..133a7cfce9cbf05c662c6aab119599f468a1372e 100644
--- a/src/gpu/gl/GrGLGpu.h
+++ b/src/gpu/gl/GrGLGpu.h
@@ -172,6 +172,11 @@ private:
                        GrPixelConfig config, const void* buffer,
                        size_t rowBytes) override;
 
+    bool onTransferPixels(GrSurface*,
+                          int left, int top, int width, int height,
+                          GrPixelConfig config, GrTransferBuffer* buffer,
+                          size_t offset, size_t rowBytes) override;
+
     void onResolveRenderTarget(GrRenderTarget* target) override;
 
     void onDraw(const DrawArgs&, const GrNonInstancedVertices&) override;