Remove support for a URLRequest having a NULL Delegate.

net/url_request/url_request.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_URL_REQUEST_URL_REQUEST_H_
 #define NET_URL_REQUEST_URL_REQUEST_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 285 matching lines @@
   // may only be changed before Start() is called.
   const std::string& referrer() const { return referrer_; }
   // Referrer is sanitized to remove URL fragment, user name and password.
   void SetReferrer(const std::string& referrer);
 
   // The referrer policy to apply when updating the referrer during redirects.
   // The referrer policy may only be changed before Start() is called.
   ReferrerPolicy referrer_policy() const { return referrer_policy_; }
   void set_referrer_policy(ReferrerPolicy referrer_policy);
 
-  // Sets the delegate of the request.  This value may be changed at any time,
-  // and it is permissible for it to be null.
+  // Sets the delegate of the request.  This is only to allow creating a request
+  // before creating its delegate.  |delegate| must be non-NULL and the request
+  // must not yet have a Delegate set.
   void set_delegate(Delegate* delegate);
 
   // Indicates that the request body should be sent using chunked transfer
   // encoding. This method may only be called before Start() is called.
   void EnableChunkedUpload();
 
   // Appends the given bytes to the request's upload data to be sent
   // immediately via chunked transfer encoding. When all data has been added,
   // set |is_last_chunk| to true to indicate the end of upload data.  All chunks
   // but the last must have |bytes_len| > 0.
@@ skipping 197 matching lines @@
   // Returns true if the request is in the process of redirecting to a new
   // URL but has not yet initiated the new request.
   bool is_redirecting() const { return is_redirecting_; }
 
   // Returns the error status of the request.
   const URLRequestStatus& status() const { return status_; }
 
   // Returns a globally unique identifier for this request.
   uint64 identifier() const { return identifier_; }
 
-  // This method is called to start the request.  The delegate will receive
-  // a OnResponseStarted callback when the request is started.
+  // This method is called to start the request.  The Delegate will receive
+  // a OnResponseStarted callback when the request is started.  The request
+  // must have a delegate set before this method is called.

[xunjieli, 2015/12/14 20:12:08]

nit: maybe s/delegate/Delegate to be consistent with the first instance of this
word in this comment.

[mmenke, 2015/12/14 20:24:11]

I decided to go with "delegate" in both places instead.  I think Delegate is
better, when we mean URLRequest::Delegate only and not NetworkDelegate, but this
file uses "delegate" almost everywhere.  May fix it in another CL, but too many
places to fix in this CL, I think.

   void Start();
 
   // This method may be called at any time after Start() has been called to
   // cancel the request.  This method may be called many times, and it has
   // no effect once the response has completed.  It is guaranteed that no
   // methods of the delegate will be called after the request has been
   // cancelled, except that this may call the delegate's OnReadCompleted()
   // during the call to Cancel itself.
   void Cancel();
 
@@ skipping 77 matching lines @@
 
   // Sets the priority level for this request and any related
   // jobs. Must not change the priority to anything other than
   // MAXIMUM_PRIORITY if the IGNORE_LIMITS load flag is set.
   void SetPriority(RequestPriority priority);
 
   // Returns true iff this request would be internally redirected to HTTPS
   // due to HSTS. If so, |redirect_url| is rewritten to the new HTTPS URL.
   bool GetHSTSRedirect(GURL* redirect_url) const;
 
-  // TODO(willchan): Undo this. Only temporarily public.
-  bool has_delegate() const { return delegate_ != NULL; }
-
   // NOTE(willchan): This is just temporary for debugging
   // http://crbug.com/90971.
   // Allows to setting debug info into the URLRequest.
   void set_stack_trace(const base::debug::StackTrace& stack_trace);
   const base::debug::StackTrace* stack_trace() const;
 
   void set_received_response_content_length(int64_t received_content_length) {
     received_response_content_length_ = received_content_length;
   }
 
@@ skipping 83 matching lines @@
   // Notifies the network delegate that the request has been completed.
   // This does not imply a successful completion. Also a canceled request is
   // considered completed.
   void NotifyRequestCompleted();
 
   // Called by URLRequestJob to allow interception when the final response
   // occurs.
   void NotifyResponseStarted();
 
   // These functions delegate to |delegate_| and may only be used if
   // |delegate_| is not NULL. See URLRequest::Delegate for the meaning

[xunjieli, 2015/12/14 20:12:08]

I think we probably can get rid of "and may only be used if |delegate_| is not
NULL", since these functions are called after Start().

[mmenke, 2015/12/14 20:24:10]

Nice catch, done!

   // of these functions.
   void NotifyAuthRequired(AuthChallengeInfo* auth_info);
   void NotifyAuthRequiredComplete(NetworkDelegate::AuthRequiredResponse result);
   void NotifyCertificateRequested(SSLCertRequestInfo* cert_request_info);
   void NotifySSLCertificateError(const SSLInfo& ssl_info, bool fatal);
   void NotifyReadCompleted(int bytes_read);
 
   // These functions delegate to |network_delegate_| if it is not NULL.
   // If |network_delegate_| is NULL, cookies can be used unless
   // SetDefaultCookiePolicyToBlock() has been called.
@@ skipping 121 matching lines @@
   HostPortPair proxy_server_;
 
   scoped_ptr<const base::debug::StackTrace> stack_trace_;
 
   DISALLOW_COPY_AND_ASSIGN(URLRequest);
 };
 
 }  // namespace net
 
 #endif  // NET_URL_REQUEST_URL_REQUEST_H_