Linux: add option to use system tcmalloc (off by default)

content/app/content_main_runner.cc

 // 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.
 
 #include "content/public/app/content_main_runner.h"
 
 #include <stdlib.h>
 
 #include "base/allocator/allocator_extension.h"
 #include "base/at_exit.h"
@@ skipping 531 matching lines @@
 
     // For tcmalloc, we need to tell it to behave like new.
     tc_set_new_mode(1);
 
     // On windows, we've already set these thunks up in _heap_init()
     base::allocator::SetGetAllocatorWasteSizeFunction(
         GetAllocatorWasteSizeThunk);
     base::allocator::SetGetStatsFunction(GetStatsThunk);
     base::allocator::SetReleaseFreeMemoryFunction(ReleaseFreeMemoryThunk);
 
+#if !defined(USE_SYSTEM_TCMALLOC)
     // Provide optional hook for monitoring allocation quantities on a
     // per-thread basis.  Only set the hook if the environment indicates this
     // needs to be enabled.
     const char* profiling = getenv(tracked_objects::kAlternateProfilerTime);
     if (profiling &&
         (atoi(profiling) == tracked_objects::TIME_SOURCE_TYPE_TCMALLOC)) {
       tracked_objects::SetAlternateTimeSource(
           MallocExtension::GetBytesAllocatedOnCurrentThread,
           tracked_objects::TIME_SOURCE_TYPE_TCMALLOC);
     }
-#endif
+#endif  // !defined(USE_SYSTEM_TCMALLOC)
+#endif  // !defined(OS_MACOSX) && defined(USE_TCMALLOC)
 
     // On Android,
     // - setlocale() is not supported.
     // - We do not override the signal handlers so that we can get
     //   stack trace when crashing.
     // - The ipc_fd is passed through the Java service.
     // Thus, these are all disabled.
 #if !defined(OS_ANDROID) && !defined(OS_IOS)
     // Set C library locale to make sure CommandLine can parse argument values
     // in correct encoding.
@@ skipping 239 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ContentMainRunnerImpl);
 };
 
 // static
 ContentMainRunner* ContentMainRunner::Create() {
   return new ContentMainRunnerImpl();
 }
 
 }  // namespace content