Have a list of pending checks instead of pending clients

chrome/browser/loader/safe_browsing_resource_throttle.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 CHROME_BROWSER_LOADER_SAFE_BROWSING_RESOURCE_THROTTLE_H_
 #define CHROME_BROWSER_LOADER_SAFE_BROWSING_RESOURCE_THROTTLE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 150 matching lines @@
   base::OneShotTimer timer_;
 
   // The redirect chain for this resource
   std::vector<GURL> redirect_urls_;
 
   // If in DEFERRED_UNCHECKED_REDIRECT state, this is the
   // URL we still need to check before resuming.
   GURL unchecked_redirect_url_;
   GURL url_being_checked_;
 
+  // TODO(vakh): The following vector should be removed after fixing
+  // http://crbug.com/660293
+  // URLs that timed out waiting for a SafeBrowsing reputation check.
+  std::vector<GURL> timed_out_urls_;

[Charlie Harrison, 2017/01/06 16:53:00]

Do we really need the GURL copies here?

The URLRequest already stores its redirect chain, and we store a copy of it
above too (is that really necessary?).

[vakh (use Gerrit instead), 2017/01/09 19:21:32]

You mean just store references to those GURLs?
For a couple of reasons:
1. It isn't clear, to me, if the SafeBrowsingResourceThrottle's lifetime is the
same as, or is greater than the URLRequest.
2. The vector will only ever be populated if the SafeBrowsing check times out.
This isn't a common occurrence.
3. This code is being added for diagnostic purposes and will be removed shortly
afterwards so optimizing it has very limited value.

[Charlie Harrison, 2017/01/09 21:46:53]

A resource throttle is owned by a ThrottlingResourceHandler. Resource handler
has the following class comment:
"A ResourceHandler's lifetime is bound to its associated URLRequest". So I think
we should be fine here.
Ack.
As long as this is true, LGTM. I would be very interested in removing the
redirect_urls_ vector as well in the future though. URLs can be big (up to 2MB
each), so adding more places where we log redirects in the browser process makes
me nervous.

+
   scoped_refptr<safe_browsing::SafeBrowsingDatabaseManager> database_manager_;
   scoped_refptr<safe_browsing::SafeBrowsingUIManager> ui_manager_;
   const net::URLRequest* request_;
   const content::ResourceType resource_type_;
   net::NetLogWithSource net_log_with_source_;
 
   DISALLOW_COPY_AND_ASSIGN(SafeBrowsingResourceThrottle);
 };
 
 #endif  // CHROME_BROWSER_LOADER_SAFE_BROWSING_RESOURCE_THROTTLE_H_