Add GrSurface::savePixels().

include/gpu/GrSurface.h

Index: include/gpu/GrSurface.h
diff --git a/include/gpu/GrSurface.h b/include/gpu/GrSurface.h
index 3aa498b6110bb00c4a0b130aedc031678ec58705..c401a905ff2177ca2ffd523c28f78639d8cc2ef7 100644
--- a/include/gpu/GrSurface.h
+++ b/include/gpu/GrSurface.h
@@ -126,6 +126,12 @@ public:
                              size_t rowBytes = 0,
                              uint32_t pixelOpsFlags = 0) = 0;
 
+    /**
+     * Write the contents of the surface to a PNG. Returns true if successful.
+     * @param filename      Full path to desired file
+     */
+    bool savePixels(const char* filename);
+
 protected:
     GrSurface(GrGpu* gpu, bool isWrapped, const GrTextureDesc& desc)
     : INHERITED(gpu, isWrapped)