Aura on Android: Common GN build overrides.

build/config/features.gni

 # Copyright 2014 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.
 
 # This file contains Chrome-feature-related build flags (see ui.gni for
 # UI-related ones). These should theoretically be moved to the build files of
 # the features themselves.
 #
 # However, today we have many "bad" dependencies on some of these flags from,
 # e.g. base, so they need to be global to match the GYP configuration. Also,
 # anything that needs a grit define must be in either this file or ui.gni.
 #
 # PLEASE TRY TO AVOID ADDING FLAGS TO THIS FILE in cases where grit isn't
 # required. See the declare_args block of BUILDCONFIG.gn for advice on how
 # to set up feature flags.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/headless_build.gni")
 if (is_android) {
   import("//build/config/android/config.gni")
 }
 
 declare_args() {
   # Multicast DNS.
   enable_mdns = is_win || is_linux
 
+  enable_extensions = !is_android && !is_ios
   enable_plugins = (!is_android && !is_ios) || is_chromecast
   enable_pdf = !is_android && !is_ios && !is_chromecast
 
   # Enables Native Client support.
   # TODO(GYP): Get NaCl linking on other platforms.
   # Also, see if we can always get rid of enable_nacl_untrusted and
   # enable_pnacl and always build them if enable_nacl is true.
   # The "is_nacl" part of the condition is needed to ensure that
   # the untrusted code is built properly; arguably it should be
   # guarded by "is_nacl" directly rather than enable_nacl_untrusted, but
@@ skipping 117 matching lines @@
 use_seccomp_bpf = (is_linux || is_android) &&
                   (current_cpu == "x86" || current_cpu == "x64" ||
                    current_cpu == "arm" || current_cpu == "mipsel")
 
 # Enable notifications everywhere except iOS.
 enable_notifications = !is_ios
 
 enable_web_speech = !is_android && !is_ios
 
 use_dbus = is_linux && !is_chromecast && !is_headless
 

[no sievers, 2015/11/24 22:45:28]

I was also just wondering why not everything is inside declare_args().
(I came across other stuff we might want to turn off in the interim, which has
dependencies on java.)

-enable_extensions = !is_android && !is_ios
-
 enable_task_manager = !is_ios && !is_android
 
 enable_themes = !is_android && !is_ios
 
 # TODO(scottmg) remove this when we've fixed printing.
 win_pdf_metafile_for_printing = true
 
 # Whether we are using the rlz library or not.  Platforms like Android send
 # rlz codes for searches but do not use the library.
 enable_rlz_support = is_win || is_mac || is_ios || is_chromeos
@@ skipping 21 matching lines @@
 enable_pre_sync_backup = is_win || is_mac || (is_linux && !is_chromeos)
 
 # Enable WebVR support by default on Android
 # Still requires command line flag to access API
 enable_webvr = is_android
 
 use_gio = is_desktop_linux && !is_headless
 
 # Chrome OS: whether to use ARC instances. Disabled by default.
 enable_arc = false