Disable "Ok Google" hotwording in open source builds by default.

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 363 matching lines @@
       # for safe browsing feature. Safe browsing can be compiled in 4 different
       # levels: 0 disables it, 1 enables it fully, and 2 enables only UI and
       # reporting features for use with Data Saver on Mobile, and 3 enables
       # extended mobile protection via an external API.  When 3 is fully
       # deployed, it will replace 2.
       'safe_browsing%': 1,
 
       # Web speech is enabled by default. Set to 0 to disable.
       'enable_web_speech%': 1,
 
-      # 'Ok Google' hotwording is enabled by default. Set to 0 to disable.
-      'enable_hotwording%': 1,
+      # 'Ok Google' hotwording is disabled by default in open source builds. Set
+      # to 1 to enable. (This will download a closed-source NaCl module at
+      # startup.) Chrome-branded builds have this enabled by default.
+      'enable_hotwording%': 0,
 
       # Notifications are compiled in by default. Set to 0 to disable.
       'notifications%' : 1,
 
       # Use dsymutil to generate real .dSYM files on Mac. The default is 0 for
       # regular builds and 1 for ASan builds.
       'mac_want_real_dsym%': 'default',
 
       # If this is set, the clang plugins used on the buildbot will be used.
       # Run tools/clang/scripts/update.sh to make sure they are compiled.
@@ skipping 410 matching lines @@
         ['OS!="ios"', {
           'enable_autofill_dialog%': 1,
 
           'conditions': [
             ['buildtype=="Official"', {
               'enable_prod_wallet_service%': 1,
             }],
           ]
         }],
 
+        ['branding=="Chrome"', {
+          'enable_hotwording%': 1,
+        }],
+
         ['OS=="android"', {
           'enable_webrtc%': 1,
         }],
 
         ['OS=="ios"', {
           'disable_ftp_support%': 1,
           'enable_extensions%': 0,
           'enable_google_now%': 0,
           'cld_version%': 2,
           'cld2_table_size%': 0,
@@ skipping 5364 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',
   },
 }