Allow the NetworkDelegate to synchronously cancel a URLRequest.

net/url_request/url_request.cc

 // Copyright (c) 2011 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.
 
 #include "net/url_request/url_request.h"
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
 #include "base/metrics/stats_counters.h"
@@ skipping 385 matching lines @@
 
 void URLRequest::set_delegate(Delegate* delegate) {
   delegate_ = delegate;
 }
 
 void URLRequest::Start() {
   response_info_.request_time = Time::Now();
 
   // Only notify the delegate for the initial request.
   if (context_ && context_->network_delegate()) {
-    if (context_->network_delegate()->NotifyBeforeURLRequest(
-            this, &before_request_callback_, &delegate_redirect_url_) ==
-            net::ERR_IO_PENDING) {
-      SetBlockedOnDelegate();
-      return;  // paused
+    int error = context_->network_delegate()->NotifyBeforeURLRequest(
+        this, &before_request_callback_, &delegate_redirect_url_);
+    if (error != net::OK) {
+      if (error == net::ERR_IO_PENDING) {
+        // Paused on the delegate, will invoke |before_request_callback_| later.
+        SetBlockedOnDelegate();
+      } else {
+        // The delegate immediately returned some error code.
+        BeforeRequestComplete(error);
+      }
+      return;
     }
   }
 
   StartJob(URLRequestJobManager::GetInstance()->CreateJob(this));
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 void URLRequest::BeforeRequestComplete(int error) {
   DCHECK(!job_);
   DCHECK_NE(ERR_IO_PENDING, error);
 
-  SetUnblockedOnDelegate();
+  if (blocked_on_delegate_)
+    SetUnblockedOnDelegate();
   if (error != OK) {
     net_log_.AddEvent(NetLog::TYPE_CANCELLED,
         make_scoped_refptr(new NetLogStringParameter("source", "delegate")));
     StartJob(new URLRequestErrorJob(this, error));
   } else if (!delegate_redirect_url_.is_empty()) {
     GURL new_url;
     new_url.Swap(&delegate_redirect_url_);
     StartJob(new URLRequestRedirectJob(this, new_url));
   } else {
     StartJob(URLRequestJobManager::GetInstance()->CreateJob(this));
@@ skipping 386 matching lines @@
   net_log_.BeginEvent(NetLog::TYPE_URL_REQUEST_BLOCKED_ON_DELEGATE, NULL);
 }
 
 void URLRequest::SetUnblockedOnDelegate() {
   blocked_on_delegate_ = false;
   load_state_param_.clear();
   net_log_.EndEvent(NetLog::TYPE_URL_REQUEST_BLOCKED_ON_DELEGATE, NULL);
 }
 
 }  // namespace net