components/metrics: Add runtime memory leak detector

third_party/tcmalloc/chromium/src/base/commandlineflags.h

 // Copyright (c) 2005, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 // 
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 100 matching lines @@
   const char* FLAGS_##name = value;                                           \
   char FLAGS_no##name;                                                        \
   }                                                                           \
   using FLAG__namespace_do_not_use_directly_use_DECLARE_string_instead::FLAGS_##name
 
 // These macros (could be functions, but I don't want to bother with a .cc
 // file), make it easier to initialize flags from the environment.
 // They are functions in Android because __system_property_get() doesn't
 // return a string.
 
-#if defined(ENABLE_PROFILING)
+#if defined(ENABLE_PROFILING) || defined(ENABLE_LEAK_DETECTOR)

[Nico, 2015/07/16 19:49:09]

This too means you can never ship this to users – enabling these flags causes
static initializers, and we don't allow static initializers in the shipping
product

[Simon Que, 2015/07/16 21:15:08]

Then the problem may extend beyond this file. I am using
REGISTER_MODULE_INITIALIZER() in leak_detector.cc ... is that a problem too?

In any case, the current CL is not for the shipping product. We will eventually
add more integration with Chrome. At that time, we can provide these flags
through Chrome (along with other parts of initialization), without having to
read environment variables or create static initializers.

[Nico, 2015/07/16 21:25:17]

Yes.
 
Makes sense :-)

 
 #if defined(__ANDROID__) || defined(ANDROID)
 
 // Returns a pointer to a static variable.  The string pointed by the returned
 // pointer must not be modified.
 inline const char* const EnvToString(const char* envname, const char* dflt) {
   static char system_property_value[PROP_VALUE_MAX];
   if (__system_property_get(envname, system_property_value) > 0)
     return system_property_value;
   return dflt;
@@ skipping 51 matching lines @@
 
 #define EnvToString(envname, dflt) (dflt)
 #define EnvToBool(envname, dflt) (dflt)
 #define EnvToInt(envname, dflt) (dflt)
 #define EnvToInt64(envname, dflt) (dflt)
 #define EnvToDouble(envname, dflt) (dflt)
 
 #endif  // defined(ENABLE_PROFILING)
 
 #endif  // BASE_COMMANDLINEFLAGS_H_