Provide mutable members of UrlRequestContext via pure-virtual interface

net/url_request/url_request_context_storage.cc

Index: net/url_request/url_request_context_storage.cc
diff --git a/net/url_request/url_request_context_storage.cc b/net/url_request/url_request_context_storage.cc
index 12ea0317cd8011abf637d982d0d1a795d1d93aad..cc570788a004e0af13ce2c92beebb1b7561f3103 100644
--- a/net/url_request/url_request_context_storage.cc
+++ b/net/url_request/url_request_context_storage.cc
@@ -17,6 +17,7 @@
 #include "net/http/http_transaction_factory.h"
 #include "net/proxy/proxy_service.h"
 #include "net/url_request/fraudulent_certificate_reporter.h"
+#include "net/url_request/http_user_agent_settings.h"
 #include "net/url_request/url_request_context.h"
 #include "net/url_request/url_request_job_factory.h"
 #include "net/url_request/url_request_throttler_manager.h"
@@ -123,4 +124,10 @@ void URLRequestContextStorage::set_throttler_manager(
   throttler_manager_.reset(throttler_manager);
 }
 
+void URLRequestContextStorage::set_http_user_agent_settings(
+    HttpUserAgentSettings* http_user_agent_settings) {
+  context_->set_http_user_agent_settings(http_user_agent_settings);
+  http_user_agent_settings_.reset(http_user_agent_settings);
+}
+
 }  // namespace net