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/PrimitiveProcessorTest.cpp b/tests/PrimitiveProcessorTest.cpp
index a6f2484..d25a33c 100644
--- a/tests/PrimitiveProcessorTest.cpp
+++ b/tests/PrimitiveProcessorTest.cpp
@@ -101,7 +101,8 @@
 };
 }
 
-DEF_GPUTEST_FOR_ALL_CONTEXTS(VertexAttributeCount, reporter, context) {
+DEF_GPUTEST_FOR_ALL_CONTEXTS(VertexAttributeCount, reporter, ctxInfo) {
+    GrContext* context = ctxInfo.fGrContext;
     GrTextureDesc desc;
     desc.fHeight = 1;
     desc.fWidth = 1;