Disable 'Ok Google' hotwording on desktop Chrome.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 7e281f42e8b4f8f611aca291e4e535f8244ee461..491a12a0232b06bd5c1ec01897ab67c1c66ad9e2 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -20,10 +20,10 @@ if (is_desktop_linux) {
 }
 
 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
+  # 'Ok Google' hotwording is disabled by default. Set to true to enable. (This
+  # will download a closed-source NaCl module at startup.) Chrome-branded
+  # ChromeOS builds have this enabled by default.
+  enable_hotwording = is_chrome_branded && is_chromeos
 }
 
 about_credits_file = "$target_gen_dir/about_credits.html"