Remove redundant c_str() calls.

base/trace_event/trace_config.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.
 
 #ifndef BASE_TRACE_EVENT_TRACE_CONFIG_H_
 #define BASE_TRACE_EVENT_TRACE_CONFIG_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 287 matching lines @@
   void WriteCategoryFilterString(const StringList& values,
                                  std::string* out,
                                  bool included) const;
   void WriteCategoryFilterString(const StringList& delays,
                                  std::string* out) const;
 
   // Returns true if the category is enabled according to this trace config.
   // This tells whether a category is enabled from the TraceConfig's
   // perspective. Please refer to IsCategoryGroupEnabled() to determine if a
   // category is enabled from the tracing runtime's perspective.
-  bool IsCategoryEnabled(const char* category_name) const;
+  bool IsCategoryEnabled(StringPiece category_name) const;
 
   static bool IsEmptyOrContainsLeadingOrTrailingWhitespace(StringPiece str);
 
   bool HasIncludedPatterns() const;
 
   TraceRecordMode record_mode_;
   bool enable_systrace_ : 1;
   bool enable_argument_filter_ : 1;
 
   MemoryDumpConfig memory_dump_config_;
 
   StringList included_categories_;
   StringList disabled_categories_;
   StringList excluded_categories_;
   StringList synthetic_delays_;
   EventFilters event_filters_;
 };
 
 }  // namespace trace_event
 }  // namespace base
 
 #endif  // BASE_TRACE_EVENT_TRACE_CONFIG_H_