If asan==1:

build/common.gypi

 # Copyright (c) 2011 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1905 matching lines @@
           }],
           ['clang==1 and clang_load!="" and clang_add_plugin!=""', {
             'cflags': [
               '-Xclang', '-load', '-Xclang', '<(clang_load)',
               '-Xclang', '-add-plugin', '-Xclang', '<(clang_add_plugin)',
             ],
           }],
           ['asan==1', {
             # Only in the linux section for now, since ASAN doesn't
             # work on Mac yet.
-            # TODO(glider): -fasan is deprecated. Remove it when we stop using
-            # it.
+            # TODO(glider): -fasan is deprecated. Remove it when we stop using
+            # it.
             'cflags': [
               '-fasan',
-              '-faddress-sanitizer',
+              '-faddress-sanitizer',
               '-w',
-              '-DADDRESS_SANITIZER',
+              '-DADDRESS_SANITIZER',
             ],
             'ldflags': [
               '-fasan',
-              '-faddress-sanitizer',
+              '-faddress-sanitizer',
             ],
           }],
           ['no_strict_aliasing==1', {
             'cflags': [
               '-fno-strict-aliasing',
             ],
           }],
           ['linux_breakpad==1', {
             'cflags': [ '-g' ],
             'defines': ['USE_LINUX_BREAKPAD'],
@@ skipping 373 matching lines @@
                   '>@(change_mach_o_flags_options)',
                 ],
               },
             ],
             'conditions': [
               ['asan==1', {
                 'variables': {
                  'asan_saves_file': 'asan.saves',
                 },
                 'xcode_settings': {
-                  'CHROMIUM_STRIP_SAVE_FILE': '<(asan_saves_file)'
+                  'CHROMIUM_STRIP_SAVE_FILE': '<(asan_saves_file)',
+                  'OTHER_CFLAGS': [
+                    '-fasan',
+                    '-faddress-sanitizer',
+                    '-w',
+                  ],
+                  'OTHER_LDFLAGS': [
+                    '-fasan',
+                    '-faddress-sanitizer',
+                    # The symbols below are referenced in the ASan runtime
+                    # library (compiled on OS X 10.6), but may be unavailable 
+                    # on the prior OS X versions. Because Chromium is currently
+                    # targeting 10.5.0, we need to explicitly mark these
+                    # symbols as dynamic_lookup.
+                    '-Wl,-U,_malloc_default_purgeable_zone',
+                    '-Wl,-U,_malloc_zone_memalign',
+                    '-Wl,-U,_dispatch_sync_f',
+                    '-Wl,-U,_dispatch_async_f',
+                    '-Wl,-U,_dispatch_barrier_async_f',
+                    '-Wl,-U,_dispatch_group_async_f',
+                    '-Wl,-U,_dispatch_after_f',
+
+                  ],
                 },
+                'defines': [
+                  'ADDRESS_SANITIZER',
+                ],
               }],
             ],
             'target_conditions': [
               ['mac_pie==1 and release_valgrind_build==0', {
                 # Turn on position-independence (ASLR) for executables. When
                 # PIE is on for the Chrome executables, the framework will
                 # also be subject to ASLR.
                 # Don't do this when building for Valgrind, because Valgrind
                 # doesn't understand slide. TODO: Make Valgrind on Mac OS X
                 # understand slide, and get rid of the Valgrind check.
@@ skipping 277 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }