Remove hotword installation code at compile time if hotwording disabled.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 3a5093927d52190371cd90a714a2353f93a1a479..a99aabf032e64dcab4a9acc78ccfa8e0b86fa2ea 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -19,13 +19,6 @@ if (is_desktop_linux) {
   import("//build/config/linux/pkg_config.gni")
 }
 
-declare_args() {
-  # 'Ok Google' hotwording is disabled by default in open source builds. Set to
-  # true to enable. (This will download a closed-source NaCl module at startup.)
-  # Chrome-branded builds have this enabled by default.
-  enable_hotwording = is_chrome_branded
-}
-
 about_credits_file = "$target_gen_dir/about_credits.html"
 additional_modules_list_file =
     "$root_gen_dir/chrome/browser/internal/additional_modules_list.txt"
@@ -458,10 +451,6 @@ source_set("browser") {
     }
   }
 
-  if (enable_hotwording) {
-    defines += [ "ENABLE_HOTWORDING" ]
-  }
-
   if (is_linux) {
     deps += [
       "//device/media_transfer_protocol",