allocator: add use_experimental_allocator_shim build flag

base/allocator/allocator.gyp

 # 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.
 
 {
   'target_defaults': {
     'variables': {
       # This code gets run a lot and debugged rarely, so it should be fast
       # by default. See http://crbug.com/388949.
       'debug_optimize': '2',
       'win_debug_Optimization': '0',
       # Run time checks are incompatible with any level of optimizations.
       'win_debug_RuntimeChecks': '0',
     },
   },
   'variables': {
     'tcmalloc_dir': '../../third_party/tcmalloc/chromium',
     'use_vtable_verify%': 0,
     # Provide a way to force disable debugallocation in Debug builds
     # e.g. for profiling (it's more rare to profile Debug builds,
     # but people sometimes need to do that).
     'disable_debugallocation%': 0,
+    'use_experimental_allocator_shim%': 0,
   },
   'targets': [
     # The only targets that should depend on allocator are 'base' and
     # executables that don't depend, directly or indirectly, on base (a few).
     # All the other targets get a transitive dependency on this target via base.
     {
       'target_name': 'allocator',
       'variables': {
         'conditions': [
           ['use_allocator!="none" or (OS=="win" and win_use_allocator_shim==1)', {
@@ skipping 300 matching lines @@
                 # cpuprofiler
                 '<(tcmalloc_dir)/src/base/thread_lister.c',
                 '<(tcmalloc_dir)/src/base/thread_lister.h',
                 '<(tcmalloc_dir)/src/profile-handler.cc',
                 '<(tcmalloc_dir)/src/profile-handler.h',
                 '<(tcmalloc_dir)/src/profiledata.cc',
                 '<(tcmalloc_dir)/src/profiledata.h',
                 '<(tcmalloc_dir)/src/profiler.cc',
               ],
             }],
+            ['use_experimental_allocator_shim==1', {
+              'defines': [
+                'TCMALLOC_DONT_REPLACE_SYSTEM_ALLOC',
+              ],
+            }]
           ],
           'configurations': {
             'Debug_Base': {
               'conditions': [
                 ['disable_debugallocation==0', {
                   'defines': [
                     # Use debugallocation for Debug builds to catch problems
                     # early and cleanly, http://crbug.com/30715 .
                     'TCMALLOC_FOR_DEBUGALLOCATION',
                   ],
@@ skipping 44 matching lines @@
                 '<(SHARED_INTERMEDIATE_DIR)/allocator',
                 '<(target_arch)',
               ],
             },
           ],
         },
       ],
     }],
   ],
 }