Put the pop-up app launcher behind a compile-time flag, and provide defines.

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 116 matching lines @@
 
           # Enable HiDPI on Mac OS and Chrome OS.
           ['OS=="mac" or chromeos==1', {
             'enable_hidpi%': 1,
           }],
 
           # Enable touch UI on Metro.
           ['OS=="win"', {
             'enable_touch_ui%': 1,
           }],
+
+          # Enable App Launcher only on ChromeOS and Windows for now.
+          ['use_ash==1 or OS=="win"', {
+            'enable_app_list%': 1,
+          }, {
+            'enable_app_list%': 0,
+          }],
         ],
       },
 
       # Copy conditionally-set variables out one scope.
       'chromeos%': '<(chromeos)',
       'host_arch%': '<(host_arch)',
       'toolkit_views%': '<(toolkit_views)',
       'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
       'use_aura%': '<(use_aura)',
       'use_ash%': '<(use_ash)',
       'use_openssl%': '<(use_openssl)',
       'use_ibus%': '<(use_ibus)',
       'enable_viewport%': '<(enable_viewport)',
       'enable_hidpi%': '<(enable_hidpi)',
       'enable_touch_ui%': '<(enable_touch_ui)',
       'android_upstream_bringup%': '<(android_upstream_bringup)',
       'android_build_type%': '<(android_build_type)',
+      'enable_app_list%': '<(enable_app_list)',
 
       # We used to provide a variable for changing how libraries were built.
       # This variable remains until we can clean up all the users.
       # This needs to be one nested variables dict in so that dependent
       # gyp files can make use of it in their outer variables.  (Yikes!)
       # http://code.google.com/p/chromium/issues/detail?id=83308
       'library%': 'static_library',
 
       # Override branding to select the desired branding flavor.
       'branding%': 'Chromium',
@@ skipping 381 matching lines @@
         ['chromeos==1', {
           # When building for ChromeOS we dont want Chromium to use libjpeg_turbo.
           'use_libjpeg_turbo%': 0,
         }],
 
         ['OS=="android"', {
           # When building as part of the Android system, use system libraries
           # where possible to reduce ROM size.
           'use_system_libjpeg%': '<(android_build_type)',
         }],
+
+        # Enable Settings App only on Windows.
+        ['enable_app_list==1 and OS=="win"', {
+          'enable_settings_app%': 1,
+        }, {
+          'enable_settings_app%': 0,
+        }],
       ],
 
       # Set this 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 internal file is missing.
       #
       # Set this to 0 to not use the internal file, even when it
       # exists in your checkout.
       #
@@ skipping 97 matching lines @@
     'enable_language_detection%': '<(enable_language_detection)',
     'enable_captive_portal_detection%': '<(enable_captive_portal_detection)',
     'disable_ftp_support%': '<(disable_ftp_support)',
     'enable_task_manager%': '<(enable_task_manager)',
     'sas_dll_path%': '<(sas_dll_path)',
     'wix_path%': '<(wix_path)',
     'android_upstream_bringup%': '<(android_upstream_bringup)',
     'use_libjpeg_turbo%': '<(use_libjpeg_turbo)',
     'use_system_libjpeg%': '<(use_system_libjpeg)',
     'android_build_type%': '<(android_build_type)',
+    'enable_app_list%': '<(enable_app_list)',
+    'enable_settings_app%': '<(enable_settings_app)',
     'use_official_google_api_keys%': '<(use_official_google_api_keys)',
     'google_api_key%': '<(google_api_key)',
     'google_default_client_id%': '<(google_default_client_id)',
     'google_default_client_secret%': '<(google_default_client_secret)',
 
     # Use system protobuf instead of bundled one.
     'use_system_protobuf%': 0,
 
     # Use system yasm instead of bundled one.
     'use_system_yasm%': 0,
@@ skipping 638 matching lines @@
       }],
       ['enable_printing==1', {
         'grit_defines': ['-D', 'enable_printing'],
       }],
       ['enable_themes==1', {
         'grit_defines': ['-D', 'enable_themes'],
       }],
       ['use_oem_wallpaper==1', {
         'grit_defines': ['-D', 'use_oem_wallpaper'],
       }],
+      ['enable_settings_app==1', {
+        'grit_defines': ['-D', 'enable_settings_app'],
+      }],
       ['clang_use_chrome_plugins==1 and OS!="win"', {
         'clang_chrome_plugins_flags': [
           '<!@(<(DEPTH)/tools/clang/scripts/plugin_flags.sh)'
         ],
       }],
 
       ['enable_web_intents_tag==1', {
         'grit_defines': ['-D', 'enable_web_intents_tag'],
       }],
 
@@ skipping 472 matching lines @@
       }],
       ['enable_language_detection==1', {
         'defines': ['ENABLE_LANGUAGE_DETECTION=1'],
       }],
       ['enable_printing==1', {
         'defines': ['ENABLE_PRINTING=1'],
       }],
       ['enable_captive_portal_detection==1', {
         'defines': ['ENABLE_CAPTIVE_PORTAL_DETECTION=1'],
       }],
+      ['enable_app_list==1', {
+        'defines': ['ENABLE_APP_LIST=1'],
+      }],
+      ['enable_settings_app==1', {
+        'defines': ['ENABLE_SETTINGS_APP=1'],
+      }],
       ['disable_ftp_support==1', {
         'defines': ['DISABLE_FTP_SUPPORT=1'],
       }],
     ],  # conditions for 'target_defaults'
     'target_conditions': [
       ['enable_wexit_time_destructors==1', {
         'conditions': [
           [ 'clang==1', {
             'cflags': [
               '-Wexit-time-destructors',
@@ skipping 1901 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',
   },
 }