Don't allow direct const char* trace value

base/debug/trace_event.h

 // Copyright (c) 2012 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 header file defines the set of trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // events to some other universe, you can copy-and-paste this file as well as
 // trace_event.h, modifying the macros contained there as necessary for the
 // target platform. The end result is that multiple libraries can funnel events
 // through to a shared trace event collector.
@@ skipping 1079 matching lines @@
   long long as_int;
   double as_double;
   const void* as_pointer;
   const char* as_string;
 };
 
 // Simple container for const char* that should be copied instead of retained.
 class TraceStringWithCopy {
  public:
   explicit TraceStringWithCopy(const char* str) : str_(str) {}
-  operator const char* () const { return str_; }
+  const char* str() const { return str_; }
  private:
   const char* str_;
 };
 
 // Define SetTraceValue for each allowed type. It stores the type and
 // value in the return arguments. This allows this API to avoid declaring any
 // structures so that it is portable to third_party libraries.
 #define INTERNAL_DECLARE_SET_TRACE_VALUE(actual_type, \
+                                         arg_expression, \
                                          union_member, \
                                          value_type_id) \
     static inline void SetTraceValue( \
         actual_type arg, \
         unsigned char* type, \
         unsigned long long* value) { \
       TraceValueUnion type_value; \
-      type_value.union_member = arg; \
+      type_value.union_member = arg_expression; \
       *type = value_type_id; \
       *value = type_value.as_uint; \
     }
 // Simpler form for int types that can be safely casted.
 #define INTERNAL_DECLARE_SET_TRACE_VALUE_INT(actual_type, \
                                              value_type_id) \
     static inline void SetTraceValue( \
         actual_type arg, \
         unsigned char* type, \
         unsigned long long* value) { \
       *type = value_type_id; \
       *value = static_cast<unsigned long long>(arg); \
     }
 
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned long long, TRACE_VALUE_TYPE_UINT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned long, TRACE_VALUE_TYPE_UINT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned int, TRACE_VALUE_TYPE_UINT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned short, TRACE_VALUE_TYPE_UINT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(unsigned char, TRACE_VALUE_TYPE_UINT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(long long, TRACE_VALUE_TYPE_INT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(long, TRACE_VALUE_TYPE_INT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(int, TRACE_VALUE_TYPE_INT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(short, TRACE_VALUE_TYPE_INT)
 INTERNAL_DECLARE_SET_TRACE_VALUE_INT(signed char, TRACE_VALUE_TYPE_INT)
-INTERNAL_DECLARE_SET_TRACE_VALUE(bool, as_bool, TRACE_VALUE_TYPE_BOOL)
-INTERNAL_DECLARE_SET_TRACE_VALUE(double, as_double, TRACE_VALUE_TYPE_DOUBLE)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const void*, as_pointer,
+INTERNAL_DECLARE_SET_TRACE_VALUE(bool, arg, as_bool, TRACE_VALUE_TYPE_BOOL)
+INTERNAL_DECLARE_SET_TRACE_VALUE(double, arg, as_double,
+                                 TRACE_VALUE_TYPE_DOUBLE)
+INTERNAL_DECLARE_SET_TRACE_VALUE(const void*, arg, as_pointer,
                                  TRACE_VALUE_TYPE_POINTER)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const char*, as_string,
+INTERNAL_DECLARE_SET_TRACE_VALUE(const char*, arg, as_string,
                                  TRACE_VALUE_TYPE_STRING)
-INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, as_string,
-                                 TRACE_VALUE_TYPE_COPY_STRING)
+INTERNAL_DECLARE_SET_TRACE_VALUE(const TraceStringWithCopy&, arg.str(),
+                                 as_string, TRACE_VALUE_TYPE_COPY_STRING)
 
 #undef INTERNAL_DECLARE_SET_TRACE_VALUE
 #undef INTERNAL_DECLARE_SET_TRACE_VALUE_INT
 
 // std::string version of SetTraceValue so that trace arguments can be strings.
 static inline void SetTraceValue(const std::string& arg,
                                  unsigned char* type,
                                  unsigned long long* value) {
   TraceValueUnion type_value;
   type_value.as_string = arg.c_str();
@@ skipping 350 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 } // namespace debug
 } // namespace base
 
 #endif /* BASE_DEBUG_TRACE_EVENT_H_ */