If we swap its arguments, SkTaskGroup::batch() _is_ sk_parallel_for.

src/core/SkMultiPictureDraw.cpp

Index: src/core/SkMultiPictureDraw.cpp
diff --git a/src/core/SkMultiPictureDraw.cpp b/src/core/SkMultiPictureDraw.cpp
index 672bd628b7c728220c667d0104bfcd4d183f00d3..57456648581beadbe8bc1c04c63e35a2e795b804 100644
--- a/src/core/SkMultiPictureDraw.cpp
+++ b/src/core/SkMultiPictureDraw.cpp
@@ -94,7 +94,7 @@ void SkMultiPictureDraw::draw(bool flush) {
         fThreadSafeDrawData[i].draw();
     }
 #else
-    sk_parallel_for(fThreadSafeDrawData.count(), [&](int i) {
+    SkTaskGroup().batch(fThreadSafeDrawData.count(), [&](int i) {
         fThreadSafeDrawData[i].draw();
     });
 #endif