Set enable_hangout_services_extension from branding.

chrome/browser/browser_resources.grd

Index: chrome/browser/browser_resources.grd
diff --git a/chrome/browser/browser_resources.grd b/chrome/browser/browser_resources.grd
index fad4f7c4a8c7c9c87ce807dd259fe1799874d989..9eb013fc38515de931a128b0d90f331e0a547c00 100644
--- a/chrome/browser/browser_resources.grd
+++ b/chrome/browser/browser_resources.grd
@@ -215,7 +215,7 @@
       <include name="IDR_SUPERVISED_USER_INTERNALS_HTML" file="resources\supervised_user_internals.html" allowexternalscript="true" compress="gzip" type="BINDATA" />
       <include name="IDR_SUPERVISED_USER_INTERNALS_CSS" file="resources\supervised_user_internals.css" compress="gzip" type="BINDATA" />
       <include name="IDR_SUPERVISED_USER_INTERNALS_JS" file="resources\supervised_user_internals.js" compress="gzip" type="BINDATA" />
-      <if expr="_google_chrome or enable_hangout_services_extension">
+      <if expr="enable_hangout_services_extension">
         <!-- Hangout Services extension, included in Google Chrome builds only. -->
         <include name="IDR_HANGOUT_SERVICES_MANIFEST" file="resources\hangout_services\manifest.json" type="BINDATA" />
       </if>