Avoid calling strlen() where possible in base/trace_config

base/trace_event/trace_event_etw_export_win.h

 // 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.
 
 // This file contains the Windows-specific exporting to ETW.
 #ifndef BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_
 #define BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_
 
 #include <stdint.h>
 
@@ skipping 38 matching lines @@
       int num_args,
       const char** arg_names,
       const unsigned char* arg_types,
       const unsigned long long* arg_values,
       const std::unique_ptr<ConvertableToTraceFormat>* convertable_values);
 
   // Exports an ETW event that marks the end of a complete event.
   static void AddCompleteEndEvent(const char* name);
 
   // Returns true if any category in the group is enabled.
-  static bool IsCategoryGroupEnabled(const char* category_group_name);
+  static bool IsCategoryGroupEnabled(StringPiece category_group_name);
 
  private:
   // Ensure only the provider can construct us.
   friend struct StaticMemorySingletonTraits<TraceEventETWExport>;
   // To have access to UpdateKeyword().
   class ETWKeywordUpdateThread;
   TraceEventETWExport();
 
   // Updates the list of enabled categories by consulting the ETW keyword.
   // Returns true if there was a change, false otherwise.
   bool UpdateEnabledCategories();
 
   // Returns true if the category is enabled.
-  bool IsCategoryEnabled(const char* category_name) const;
+  bool IsCategoryEnabled(StringPiece category_name) const;
 
   // Called back by the update thread to check for potential changes to the
   // keyword.
   static void UpdateETWKeyword();
 
   // True if ETW is enabled. Allows hiding the exporting behind a flag.
   bool etw_export_enabled_;
 
   // Maps category names to their status (enabled/disabled).
   std::map<StringPiece, bool> categories_status_;
 
   // Local copy of the ETW keyword.
   uint64_t etw_match_any_keyword_;
 
   // Background thread that monitors changes to the ETW keyword and updates
   // the enabled categories when a change occurs.
   std::unique_ptr<ETWKeywordUpdateThread> keyword_update_thread_;
   PlatformThreadHandle keyword_update_thread_handle_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceEventETWExport);
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_EVENT_ETW_EXPORT_WIN_H_