Add documentation in memory_benchmarks.md on finding links to trace files

net/url_request/url_request_context.h

Index: net/url_request/url_request_context.h
diff --git a/net/url_request/url_request_context.h b/net/url_request/url_request_context.h
index 2b00768fa34c84e91a30b5c6493e560b80927e34..6a8a145491c01c932a40609d9ae3173aa2507bb8 100644
--- a/net/url_request/url_request_context.h
+++ b/net/url_request/url_request_context.h
@@ -281,6 +281,8 @@ class NET_EXPORT URLRequestContext
   void set_name(const char* name) { name_ = name; }
 
   // MemoryDumpProvider implementation:
+  // This is reported as
+  // "memory:chrome:all_processes:reported_by_chrome:net:effective_size_avg."
   bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     base::trace_event::ProcessMemoryDump* pmd) override;