Add default / empty implementation of new API method to avoid breaking things

Bug: skia:13303
Change-Id: I898770b07524154827918356d549bd97768a7492
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/564061
Commit-Queue: Nicolette Prevost <nicolettep@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/include/utils/SkEventTracer.h b/include/utils/SkEventTracer.h
index c1f245b..2ec0a3b 100644
--- a/include/utils/SkEventTracer.h
+++ b/include/utils/SkEventTracer.h
@@ -78,7 +78,8 @@
                                  const char* name,
                                  SkEventTracer::Handle handle) = 0;
 
-    virtual void newTracingSection(const char* name) = 0;
+    // Optional method that can be implemented to allow splitting up traces into different sections.
+    virtual void newTracingSection(const char*) {}
 
 protected:
     SkEventTracer() = default;