One signature for creating unit tests that run on premade GrContexts

tests/SRGBReadWritePixelsTest.cpp

Index: tests/SRGBReadWritePixelsTest.cpp
diff --git a/tests/SRGBReadWritePixelsTest.cpp b/tests/SRGBReadWritePixelsTest.cpp
index 1446d7d0acffc52035dcc363c98e13df03168812..1067baa9e2e30ee59f10a5a95c7946dc7f045b04 100644
--- a/tests/SRGBReadWritePixelsTest.cpp
+++ b/tests/SRGBReadWritePixelsTest.cpp
@@ -138,7 +138,8 @@ void read_and_check_pixels(skiatest::Reporter* reporter, GrTexture* texture, uin
 
 // TODO: Add tests for copySurface between srgb/linear textures. Add tests for unpremul/premul
 // conversion during read/write along with srgb/linear conversions.
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SRGBReadWritePixels, reporter, context) {
+DEF_GPUTEST_FOR_RENDERING_CONTEXTS(SRGBReadWritePixels, reporter, ctxInfo) {
+    GrContext* context = ctxInfo.fGrContext;
 #if defined(GOOGLE3)
     // Stack frame size is limited in GOOGLE3.
     static const int kW = 63;