Perform redirect checks before OnReceivedRedirect in //net.

net/url_request/url_request_job.h

Index: net/url_request/url_request_job.h
diff --git a/net/url_request/url_request_job.h b/net/url_request/url_request_job.h
index 2341999ae5493b1e205343963b41d8cbc68549de..c6eb1285cd06cd104b4fae43227ceb20758aad6d 100644
--- a/net/url_request/url_request_job.h
+++ b/net/url_request/url_request_job.h
@@ -345,6 +345,10 @@ class NET_EXPORT URLRequestJob : public base::PowerObserver {
                         int buf_size,
                         const CompletionCallback& callback);
 
+  // Returns OK if |new_url| is a valid redirect target and an error code
+  // otherwise.
+  int CanFollowRedirect(const GURL& new_url);
+
   // Called in response to a redirect that was not canceled to follow the
   // redirect. The current job will be replaced with a new job loading the
   // given redirect destination.