Adding a new SkSurface factory for generating surfaces from the scratch texture pool.

include/core/SkSurface.h

Index: include/core/SkSurface.h
diff --git a/include/core/SkSurface.h b/include/core/SkSurface.h
index 8e430d8f47d2d0cfa6e626678d1b29b55cfa8a5b..e72d43979c3065c3b92098f5e785630e39ab715a 100644
--- a/include/core/SkSurface.h
+++ b/include/core/SkSurface.h
@@ -73,6 +73,13 @@ public:
      */
     static SkSurface* NewRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0);
 
+    /**
+     *  Return a new surface whose contents will be drawn to an offscreen
+     *  render target, allocated by the surface from the scratch texture pool
+     *  managed by the GrContext.
+     */
+    static SkSurface* NewScratchRenderTarget(GrContext*, const SkImageInfo&, int sampleCount = 0);
+
     int width() const { return fWidth; }
     int height() const { return fHeight; }