Remove hotword installation code at compile time if hotwording disabled.

build/config/BUILD.gn

 # Copyright (c) 2013 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.
 
 import("//build/config/allocator.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ skipping 243 matching lines @@
     defines += [ "OFFICIAL_BUILD" ]
   }
   if (is_chrome_branded) {
     defines += [ "GOOGLE_CHROME_BUILD" ]
   } else {
     defines += [ "CHROMIUM_BUILD" ]
   }
   if (enable_media_router) {
     defines += [ "ENABLE_MEDIA_ROUTER=1" ]
   }
+  if (enable_hotwording) {
+    defines += [ "ENABLE_HOTWORDING" ]
+  }
   if (enable_webvr) {
     defines += [ "ENABLE_WEBVR" ]
   }
   if (is_syzyasan) {
     defines += [
       "SYZYASAN",
       "MEMORY_TOOL_REPLACES_ALLOCATOR",
       "MEMORY_SANITIZER_INITIAL_SIZE",
     ]
   }
@@ skipping 198 matching lines @@
     # This error doesn't happen every time. In VS2013, it seems if the .pch
     # file doesn't exist, no error will be generated (probably MS tested this
     # case but forgot the other one?). To reproduce this error, do a build,
     # then delete the precompile.c.obj file, then build again.
     cflags_c = [ "/wd4206" ]
   } else if (is_mac && !is_official_build && !use_goma) {
     precompiled_header = "build/precompile.h"
     precompiled_source = "//build/precompile.h"
   }
 }