Put the syzygy targets behind a 'syzygy_optimize' flag.

build/common.gypi

 # 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.
 
 # 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 500 matching lines @@
       'data_reduction_fallback_host%' : '',
       'data_reduction_dev_host%' : '',
       'spdy_proxy_auth_origin%' : '',
       'spdy_proxy_auth_property%' : '',
       'spdy_proxy_auth_value%' : '',
       'data_reduction_proxy_probe_url%' : '',
       'enable_mdns%' : 0,
       'enable_enhanced_bookmarks%': 0,
       'enable_hangout_services_extension%': 0,
 
+       # Enable the Syzygy optimization step.
+      'syzygy_optimize%': 0,
+
       'conditions': [
         # A flag for POSIX platforms
         ['OS=="win"', {
           'os_posix%': 0,
         }, {
           'os_posix%': 1,
         }],
 
         # A flag for BSD platforms
         ['OS=="freebsd" or OS=="openbsd"', {
@@ skipping 288 matching lines @@
         }],
 
         # By default, use ICU data file (icudtl.dat) on all platforms
         # except when building Android WebView.
         # TODO(jshin): Handle 'use_system_icu' on Linux (Chromium).
         ['android_webview_build==0', {
           'icu_use_data_file_flag%' : 1,
         }, {
           'icu_use_data_file_flag%' : 0,
         }],
+
+        # Enable the Syzygy optimization step for the official builds.
+        ['OS=="win" and buildtype=="Official"', {
+          'syzygy_optimize%': 1,
+        }, {
+          'syzygy_optimize%': 0,
+        }],

[chrisha, 2014/03/14 22:01:36]

Is there any meaningful way for us to explode with a message if both
syzygy_optimize and syzyasan are set?

[Sébastien Marchand, 2014/03/17 17:41:14]

No (afaik), I've added an extra check here but preventing both variables to be
set seems tricky...(i.e. we'll have to run a command that will fail and print
the message)

       ],
 
       # Set this to 1 to enable use of concatenated impulse responses
       # for the HRTF panner in WebAudio.
       'use_concatenated_impulse_responses': 1,
 
       # You can set the variable 'use_official_google_api_keys' to 1
       # to use the Google-internal file containing official API keys
       # for Google Chrome even in a developer build.  Setting this
       # variable explicitly to 1 will cause your build to fail if the
@@ skipping 93 matching lines @@
     'chromium_win_pch%': '<(chromium_win_pch)',
     'configuration_policy%': '<(configuration_policy)',
     'safe_browsing%': '<(safe_browsing)',
     'input_speech%': '<(input_speech)',
     'notifications%': '<(notifications)',
     'clang_use_chrome_plugins%': '<(clang_use_chrome_plugins)',
     'mac_want_real_dsym%': '<(mac_want_real_dsym)',
     'asan%': '<(asan)',
     'asan_coverage%': '<(asan_coverage)',
     'syzyasan%': '<(syzyasan)',
+    'syzygy_optimize%': '<(syzygy_optimize)',
     'lsan%': '<(lsan)',
     'msan%': '<(msan)',
     'msan_blacklist%': '<(msan_blacklist)',
     'tsan%': '<(tsan)',
     'tsan_blacklist%': '<(tsan_blacklist)',
     'use_instrumented_libraries%': '<(use_instrumented_libraries)',
     'use_custom_libcxx%': '<(use_custom_libcxx)',
     'clang_type_profiler%': '<(clang_type_profiler)',
     'order_profiling%': '<(order_profiling)',
     'order_text_section%': '<(order_text_section)',
@@ skipping 4071 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',
   },
 }