Avoid calling strlen() where possible in base/trace_config

base/trace_event/trace_config.cc

 // Copyright (c) 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 "base/trace_event/trace_config.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 168 matching lines @@
     return false;
   for (size_t i = 0; i < list->GetSize(); ++i) {
     std::string value;
     if (list->GetString(i, &value))
       out_set->insert(value);
   }
   return true;
 }
 
 bool TraceConfig::EventFilterConfig::IsCategoryGroupEnabled(
-    const char* category_group_name) const {
+    const StringPiece& category_group_name) const {
   return category_filter_.IsCategoryGroupEnabled(category_group_name);
 }
 
 TraceConfig::TraceConfig() {
   InitializeDefault();
 }
 
 TraceConfig::TraceConfig(StringPiece category_filter_string,
                          StringPiece trace_options_string) {
   InitializeFromStrings(category_filter_string, trace_options_string);
@@ skipping 70 matching lines @@
 std::unique_ptr<ConvertableToTraceFormat>
 TraceConfig::AsConvertableToTraceFormat() const {
   return MakeUnique<ConvertableTraceConfigToTraceFormat>(*this);
 }
 
 std::string TraceConfig::ToCategoryFilterString() const {
   return category_filter_.ToFilterString();
 }
 
 bool TraceConfig::IsCategoryGroupEnabled(
-    const char* category_group_name) const {
+    const StringPiece& category_group_name) const {
   // TraceLog should call this method only as part of enabling/disabling
   // categories.
   return category_filter_.IsCategoryGroupEnabled(category_group_name);
 }
 
 void TraceConfig::Merge(const TraceConfig& config) {
   if (record_mode_ != config.record_mode_
       || enable_systrace_ != config.enable_systrace_
       || enable_argument_filter_ != config.enable_argument_filter_) {
     DLOG(ERROR) << "Attempting to merge trace config with a different "
@@ skipping 292 matching lines @@
   }
   if (enable_systrace_)
     ret = ret + "," + kEnableSystrace;
   if (enable_argument_filter_)
     ret = ret + "," + kEnableArgumentFilter;
   return ret;
 }
 
 }  // namespace trace_event
 }  // namespace base