Make URLRequestThrottlerManager a member of URLRequestContext.

content/common/net/url_fetcher_core.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 CONTENT_COMMON_NET_URL_FETCHER_CORE_H_
 #define CONTENT_COMMON_NET_URL_FETCHER_CORE_H_
 #pragma once
 
 #include <set>
 #include <string>
@@ skipping 320 matching lines @@
   bool was_fetched_via_proxy_;
   net::HostPortPair socket_address_;
 
   std::string upload_content_;       // HTTP POST payload
   std::string upload_content_type_;  // MIME type of POST payload
   std::string referrer_;             // HTTP Referer header value
   bool is_chunked_upload_;           // True if using chunked transfer encoding
 
   // Used to determine how long to wait before making a request or doing a
   // retry.
+  //
   // Both of them can only be accessed on the IO thread.
-  // We need not only the throttler entry for |original_URL|, but also the one
-  // for |url|. For example, consider the case that URL A redirects to URL B,
-  // for which the server returns a 500 response. In this case, the exponential
-  // back-off release time of URL A won't increase. If we retry without
-  // considering the back-off constraint of URL B, we may send out too many
-  // requests for URL A in a short period of time.
+  //
+  // We need not only the throttler entry for |original_URL|, but also
+  // the one for |url|. For example, consider the case that URL A
+  // redirects to URL B, for which the server returns a 500
+  // response. In this case, the exponential back-off release time of
+  // URL A won't increase. If we retry without considering the
+  // back-off constraint of URL B, we may send out too many requests
+  // for URL A in a short period of time.
+  //
+  // Both of these will be NULL if
+  // URLRequestContext::throttler_manager() is NULL.
   scoped_refptr<net::URLRequestThrottlerEntryInterface>
       original_url_throttler_entry_;
   scoped_refptr<net::URLRequestThrottlerEntryInterface> url_throttler_entry_;
 
   // |num_retries_| indicates how many times we've failed to successfully
   // fetch this URL.  Once this value exceeds the maximum number of retries
   // specified by the owner URLFetcher instance, we'll give up.
   int num_retries_;
 
   // True if the URLFetcher has been cancelled.
@@ skipping 31 matching lines @@
   int64 total_response_bytes_;
 
   static base::LazyInstance<Registry> g_registry;
 
   DISALLOW_COPY_AND_ASSIGN(URLFetcherCore);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_NET_URL_FETCHER_CORE_H_