One signature for creating unit tests that run on premade GrContexts
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1860593002

Review URL: https://codereview.chromium.org/1860593002
diff --git a/tests/ImageNewShaderTest.cpp b/tests/ImageNewShaderTest.cpp
index 4ae0b6d..164f118 100644
--- a/tests/ImageNewShaderTest.cpp
+++ b/tests/ImageNewShaderTest.cpp
@@ -139,15 +139,15 @@
     runShaderTest(reporter, sourceSurface.get(), destinationSurface.get(), info);
 }
 
-DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ImageNewShader_GPU, reporter, context) {
+DEF_GPUTEST_FOR_RENDERING_CONTEXTS(ImageNewShader_GPU, reporter, ctxInfo) {
     //  GPU -> GPU
-    gpuToGpu(reporter, context);
+    gpuToGpu(reporter, ctxInfo.fGrContext);
 
     //  GPU -> RASTER
-    gpuToRaster(reporter, context);
+    gpuToRaster(reporter, ctxInfo.fGrContext);
 
     //  RASTER -> GPU
-    rasterToGpu(reporter, context);
+    rasterToGpu(reporter, ctxInfo.fGrContext);
 }
 
 #endif