Mark URLRequest::GetResponseCode() as const

The URLRequestJob interface this forwards to is const, and marking URLRequest::GetResponseCode() as const allows passing the URLRequest as const in some cases.

BUG=none

Review URL: https://chromiumcodereview.appspot.com/23494023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221958 0039d316-1c4b-4281-b951-d872f2087c98

net/url_request/url_request.cc

@@ -453,7 +453,7 @@ void URLRequest::GetCharset(string* charset) {
   job_->GetCharset(charset);
 }
 
-int URLRequest::GetResponseCode() {
+int URLRequest::GetResponseCode() const {
   DCHECK(job_.get());
   return job_->GetResponseCode();
 }

net/url_request/url_request.h

@@ -528,7 +528,7 @@ class NET_EXPORT URLRequest : NON_EXPORTED_BASE(public base::NonThreadSafe),
   // Returns the HTTP response code (e.g., 200, 404, and so on).  This method
   // may only be called once the delegate's OnResponseStarted method has been
   // called.  For non-HTTP requests, this method returns -1.
-  int GetResponseCode();
+  int GetResponseCode() const;
 
   // Get the HTTP response info in its entirety.
   const HttpResponseInfo& response_info() const { return response_info_; }