Add helper for creating leaf FPs inside GrFP::TestCreate functions

src/gpu/GrProcessor.cpp

Index: src/gpu/GrProcessor.cpp
diff --git a/src/gpu/GrProcessor.cpp b/src/gpu/GrProcessor.cpp
index 6ab556194236b5d2f85ec7fd68fa0318f329b5e1..782b82ba5c34701faa21dfb67c43c38e22a3bf82 100644
--- a/src/gpu/GrProcessor.cpp
+++ b/src/gpu/GrProcessor.cpp
@@ -50,7 +50,7 @@ GrProcessorTestFactory<GrGeometryProcessor>::GetFactories() {
  * we verify the count is as expected.  If a new factory is added, then these numbers must be
  * manually adjusted.
  */
-static const int kFPFactoryCount = 38;
+static const int kFPFactoryCount = 39;
 static const int kGPFactoryCount = 14;
 static const int kXPFactoryCount = 5;