Add helper for creating a SkSurface from a client created texture.

src/image/SkSurface.cpp

Index: src/image/SkSurface.cpp
diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index 2d3fa2bf7a4eeee1e0d46943c40d45e8d73ee2b7..a99997306be1b2c36557f2d06a241f78762b171f 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -188,5 +188,9 @@ SkSurface* SkSurface::NewRenderTarget(GrContext*, Budgeted, const SkImageInfo&,
     return NULL;
 }
 
+SkSurface* SkSurface::NewWrappedRenderTarget(GrContext*, GrBackendTextureDesc,
+                                             const SkSurfaceProps*) {
+    return NULL;
+}
 
 #endif