Move non-gencode `onDumpInfo` methods to private section.

`onXxxxx` methods in Skia are generally intended to be non-public.

Change-Id: I26b6bdcee653f41a22c91f79d01b20a274210747
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/309981
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/ops/GrOp.h b/src/gpu/ops/GrOp.h
index fac22ae..66ff71f 100644
--- a/src/gpu/ops/GrOp.h
+++ b/src/gpu/ops/GrOp.h
@@ -181,7 +181,6 @@
 
     /** Used for spewing information about ops when debugging. */
 #if GR_TEST_UTILS
-    virtual SkString onDumpInfo() const { return SkString(); }
     virtual SkString dumpInfo() const final {
         return SkStringPrintf("%s\nOpBounds: [L: %.2f, T: %.2f, R: %.2f, B: %.2f]",
                               this->onDumpInfo().c_str(), fBounds.fLeft, fBounds.fTop,
@@ -302,6 +301,9 @@
     // If this op is chained then chainBounds is the union of the bounds of all ops in the chain.
     // Otherwise, this op's bounds.
     virtual void onExecute(GrOpFlushState*, const SkRect& chainBounds) = 0;
+#if GR_TEST_UTILS
+    virtual SkString onDumpInfo() const { return SkString(); }
+#endif
 
     static uint32_t GenID(std::atomic<uint32_t>* idCounter) {
         uint32_t id = (*idCounter)++;