Delay generation of User-Agent header to URLRequestHttpJob and accept custom User-Agent from XHR/Fe…

net/url_request/url_request.cc

Index: net/url_request/url_request.cc
diff --git a/net/url_request/url_request.cc b/net/url_request/url_request.cc
index eac30aeb4157f9f54ea97f57c3ce1c6d2a91fbb6..324a5a1ed328a2adb9ebaafe5ceb260f29d7a2e8 100644
--- a/net/url_request/url_request.cc
+++ b/net/url_request/url_request.cc
@@ -222,6 +222,15 @@ void URLRequest::SetExtraRequestHeaders(
   // for request headers are implemented.
 }
 
+void URLRequest::set_default_user_agent(const std::string& default_user_agent) {
+  has_default_user_agent_ = true;
+  default_user_agent_ = default_user_agent;
+}
+
+bool URLRequest::has_default_user_agent() const {
+  return has_default_user_agent_;
+}
+
 bool URLRequest::GetFullRequestHeaders(HttpRequestHeaders* headers) const {
   if (!job_.get())
     return false;
@@ -553,6 +562,7 @@ URLRequest::URLRequest(const GURL& url,
       method_("GET"),
       referrer_policy_(CLEAR_REFERRER_ON_TRANSITION_FROM_SECURE_TO_INSECURE),
       first_party_url_policy_(NEVER_CHANGE_FIRST_PARTY_URL),
+      has_default_user_agent_(false),
       load_flags_(LOAD_NORMAL),
       delegate_(delegate),
       is_pending_(false),