Allocator shim skeleton + Linux impl behind a 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 338 matching lines @@
         }],
         ['order_profiling != 0', {
           'target_conditions' : [
             ['_toolset=="target"', {
               'cflags!': [ '-finstrument-functions' ],
             }],
           ],
         }],
       ],  # conditions of 'allocator' target.
     },  # 'allocator' target.
+    {
+      # GN: //base/allocator:features
+      'target_name': 'allocator_features',
+      'includes': [ '../../build/buildflag_header.gypi' ],
+      'toolsets': ['host', 'target'],
+      'variables': {
+        'buildflag_header_path': 'base/allocator/features.h',
+        'buildflag_flags': [
+          'USE_EXPERIMENTAL_ALLOCATOR_SHIM=<(use_experimental_allocator_shim)',
+        ],
+      },
+    },  # 'allocator_features' target.
   ],  # targets.
   'conditions': [
     ['OS=="win" and win_use_allocator_shim==1', {
       'targets': [
         {
           'target_name': 'libcmt',
           'toolsets': ['host', 'target'],
           'type': 'none',
           'actions': [
             {
               'action_name': 'libcmt',
               'inputs': [
                 'prep_libc.py',
               ],
               'outputs': [
                 '<(SHARED_INTERMEDIATE_DIR)/allocator/libcmt.lib',
               ],
               'action': [
                 'python',
                 'prep_libc.py',
                 '$(VCInstallDir)lib',
                 '<(SHARED_INTERMEDIATE_DIR)/allocator',
                 '<(target_arch)',
               ],
             },
           ],
         },
       ],
     }],
+    ['use_experimental_allocator_shim==1', {
+      'targets': [
+        {
+          # GN: //base/allocator:unified_allocator_shim
+          'target_name': 'unified_allocator_shim',
+          'toolsets': ['host', 'target'],
+          'type': 'static_library',
+          'defines': [ 'BASE_IMPLEMENTATION' ],
+          'sources': [
+            'allocator_shim.cc',
+            'allocator_shim.h',
+            'allocator_shim_internals.h',
+            'allocator_shim_override_cpp_symbols.h',
+            'allocator_shim_override_libc_symbols.h',
+          ],
+          'include_dirs': [
+            '../..',
+          ],
+          'conditions': [
+            ['OS=="linux" and use_allocator=="tcmalloc"', {
+              'sources': [
+                'allocator_shim_default_dispatch_to_tcmalloc.cc',
+                'allocator_shim_override_glibc_weak_symbols.h',
+              ],
+            }],
+            ['OS=="linux" and use_allocator=="none"', {
+              'sources': [
+                'allocator_shim_default_dispatch_to_glibc.cc',
+              ],
+            }],
+          ]
+        },  # 'unified_allocator_shim' target.
+      ],
+    }]
   ],
 }