[Extensions] Don't allow built-in extensions code to be overridden

extensions/renderer/resources/send_request.js

Index: extensions/renderer/resources/send_request.js
diff --git a/extensions/renderer/resources/send_request.js b/extensions/renderer/resources/send_request.js
index 3dc523c4f6951933006477d86ac35c531731c7da..1692aaa79284f633b37992db150f7e6f434f4ce5 100644
--- a/extensions/renderer/resources/send_request.js
+++ b/extensions/renderer/resources/send_request.js
@@ -140,10 +140,10 @@ function clearCalledSendRequest() {
   calledSendRequest = false;
 }
 
-exports.sendRequest = sendRequest;
-exports.getCalledSendRequest = getCalledSendRequest;
-exports.clearCalledSendRequest = clearCalledSendRequest;
-exports.safeCallbackApply = safeCallbackApply;
+exports.$set('sendRequest', sendRequest);
+exports.$set('getCalledSendRequest', getCalledSendRequest);
+exports.$set('clearCalledSendRequest', clearCalledSendRequest);
+exports.$set('safeCallbackApply', safeCallbackApply);
 
 // Called by C++.
-exports.handleResponse = handleResponse;
+exports.$set('handleResponse', handleResponse);