Move some parts of onReadPixels up to GrGpu readPixels.

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index e6f37cc1cfc881e9350444b23071bc202acd8fe0..b814abf68879ba243679a83b415c2330b3365aee 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -470,7 +470,8 @@ private:
 
     // overridden by backend-specific derived class to perform the surface read
     virtual bool onReadPixels(GrSurface*,
-                              int left, int top, int width, int height,
+                              int left, int top,
+                              int width, int height,
                               GrPixelConfig,
                               void* buffer,
                               size_t rowBytes) = 0;