add SkImage::newSurface

BUG=skia:

Review URL: https://codereview.chromium.org/741763002
diff --git a/src/image/SkSurface.cpp b/src/image/SkSurface.cpp
index b10782a..3ca5747 100644
--- a/src/image/SkSurface.cpp
+++ b/src/image/SkSurface.cpp
@@ -47,6 +47,11 @@
     : fFlags(flags), fPixelGeometry(pg)
 {}
 
+SkSurfaceProps::SkSurfaceProps(const SkSurfaceProps& other)
+    : fFlags(other.fFlags)
+    , fPixelGeometry(other.fPixelGeometry)
+{}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 SkSurface_Base::SkSurface_Base(int width, int height, const SkSurfaceProps* props)