tracing: Add the TimeTicks clock source as trace metadata

chrome/common/trace_event_args_whitelist.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/trace_event_args_whitelist.h"
 
 #include "base/bind.h"
 #include "base/strings/pattern.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
 
 namespace {
 
 struct WhitelistEntry {
   const char* category_name;
   const char* event_name;
   const char* const* arg_name_filter;
 };
 
 const char* const kInputLatencyAllowedArgs[] = {"data", nullptr};
 
 const WhitelistEntry kEventArgsWhitelist[] = {
     {"__metadata", "thread_name", nullptr},
     {"ipc", "SyncChannel::Send", nullptr},
     {"toplevel", "*", nullptr},
     {"latencyInfo", "*", kInputLatencyAllowedArgs},
     {nullptr, nullptr, nullptr}};
 
 const char* kMetadataWhitelist[] = {
+  "clock-domain",
   "command_line",
   "config",
   "cpu-*",
   "field-trials",
   "gpu-*",
   "highres-ticks",
   "network-type",
   "num-cpus",
   "os-*",
   "physical-memory",
@@ skipping 43 matching lines @@
 }
 
 bool IsMetadataWhitelisted(const std::string& metadata_name) {
   for (auto key : kMetadataWhitelist) {
     if (base::MatchPattern(metadata_name, key)) {
       return true;
     }
   }
   return false;
 }