Added support to trace_event for passing static string arguments without copy

base/debug/trace_event.cc

Index: base/debug/trace_event.cc
diff --git a/base/debug/trace_event.cc b/base/debug/trace_event.cc
index c983df9a4468e416f6a331aa634906db9d6fd0ca..747225d4f0b07cad97830cd8c71e30efd2929a62 100644
--- a/base/debug/trace_event.cc
+++ b/base/debug/trace_event.cc
@@ -83,9 +83,10 @@ void TraceValue::AppendAsJSON(std::string* out) const {
       *out += temp_string;
       break;
     case TRACE_TYPE_STRING:
+    case TRACE_TYPE_STATIC_STRING:
       *out += "\"";
       start_pos = out->size();
-      *out += as_string();
+      *out += as_string()? as_string() : "NULL";
       // replace " character with '
       while ((start_pos = out->find_first_of('\"', start_pos)) !=
              std::string::npos)
@@ -440,28 +441,6 @@ int TraceLog::AddTraceEvent(TraceEventPhase phase,
   return ret_begin_id;
 }
 
-void TraceLog::AddTraceEventEtw(TraceEventPhase phase,
-                                const char* name,
-                                const void* id,
-                                const char* extra) {
-  // Legacy trace points on windows called to ETW
-#if defined(OS_WIN)
-  TraceEventETWProvider::Trace(name, phase, id, extra);
-#endif
-
-  // Also add new trace event behavior
-  static const TraceCategory* category = GetCategory("ETW Trace Event");
-  if (category->enabled) {
-    TraceLog* tracelog = TraceLog::GetInstance();
-    if (!tracelog)
-      return;
-    tracelog->AddTraceEvent(phase, category, name,
-                            "id", id,
-                            "extra", extra ? extra : "",
-                            -1, 0, false);
-  }
-}
-
 void TraceLog::AddCurrentMetadataEvents() {
   lock_.AssertAcquired();
   for(base::hash_map<PlatformThreadId, std::string>::iterator it =
@@ -474,7 +453,7 @@ void TraceLog::AddCurrentMetadataEvents() {
                      it->first,
                      TimeTicks(), base::debug::TRACE_EVENT_PHASE_METADATA,
                      g_category_metadata, "thread_name",
-                     "name", it->second.c_str(),
+                     "name", it->second,
                      NULL, 0,
                      false));
   }