Belt and suspenders for colors in DrawAtlasBatch test

src/gpu/batches/GrDrawAtlasBatch.cpp

Index: src/gpu/batches/GrDrawAtlasBatch.cpp
diff --git a/src/gpu/batches/GrDrawAtlasBatch.cpp b/src/gpu/batches/GrDrawAtlasBatch.cpp
index f79412be548562e40d6346011688e103c6767392..c89fb570ffa68af7942dd65ea6ae39e658bc0559 100644
--- a/src/gpu/batches/GrDrawAtlasBatch.cpp
+++ b/src/gpu/batches/GrDrawAtlasBatch.cpp
@@ -251,7 +251,7 @@ BATCH_TEST_DEFINE(GrDrawAtlasBatch) {
     GrDrawAtlasBatch::Geometry geometry;
     geometry.fColor = GrRandomColor(random);
     return GrDrawAtlasBatch::Create(geometry, viewMatrix, spriteCount, xforms.begin(),
-                                    texRects.begin(), colors.begin());
+                                    texRects.begin(), hasColors ? colors.begin() : nullptr);
 }
 
 #endif