Hide GrPixelConfig in SkSurfaceCharacterization

TBR=bsalomon@google.com
Change-Id: Ifc38d0ca2b18128d27c187f789461fea62d1edae
Reviewed-on: https://skia-review.googlesource.com/117440
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/image/SkSurface_Gpu.h b/src/image/SkSurface_Gpu.h
index 3edb0ca..c23da72 100644
--- a/src/image/SkSurface_Gpu.h
+++ b/src/image/SkSurface_Gpu.h
@@ -41,7 +41,7 @@
     SkGpuDevice* getDevice() { return fDevice.get(); }
 
     static bool Valid(const SkImageInfo&);
-    static bool Valid(GrContext*, GrPixelConfig, SkColorSpace*);
+    static bool Valid(const GrCaps*, GrPixelConfig, SkColorSpace*);
 
 private:
     sk_sp<SkGpuDevice> fDevice;