Move EmptyString, kWhitespace and the BOM to base.

net/url_request/url_request_context.cc

Index: net/url_request/url_request_context.cc
diff --git a/net/url_request/url_request_context.cc b/net/url_request/url_request_context.cc
index b5c531342ea37684c4610c15451508bc8f22dd45..391842f0e8abfad685d11a2263190d47a9618871 100644
--- a/net/url_request/url_request_context.cc
+++ b/net/url_request/url_request_context.cc
@@ -81,12 +81,12 @@ void URLRequestContext::set_cookie_store(CookieStore* cookie_store) {
 
 std::string URLRequestContext::GetAcceptLanguage() const {
   return http_user_agent_settings_ ?
-      http_user_agent_settings_->GetAcceptLanguage() : EmptyString();
+      http_user_agent_settings_->GetAcceptLanguage() : std::string();
 }
 
 std::string URLRequestContext::GetUserAgent(const GURL& url) const {
   return http_user_agent_settings_ ?
-      http_user_agent_settings_->GetUserAgent(url) : EmptyString();
+      http_user_agent_settings_->GetUserAgent(url) : std::string();
 }
 
 void URLRequestContext::AssertNoURLRequests() const {