Fix purify freeze. Revert "Use a priority queue to assure that subresources are resolved asap"

chrome/browser/net/dns_host_info.h

 // Copyright (c) 2006-2008 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.
 
 // A DnsHostInfo object is used to store status of a Dns lookup of a specific
 // hostname.
 // It includes progress, from placement in the DnsMaster's queue, to resolution
 // by the DNS service as either FOUND or NO_SUCH_NAME.
 
 #ifndef CHROME_BROWSER_NET_DNS_HOST_INFO_H_
@@ skipping 34 matching lines @@
     // The following involve predictive prefetching, triggered by a navigation.
     // The referring_hostname_ is also set when these are used.
     // TODO(jar): Support STATIC_REFERAL_MOTIVATED API and integration.
     STATIC_REFERAL_MOTIVATED,  // External database suggested this resolution.
     LEARNED_REFERAL_MOTIVATED,  // Prior navigation taught us this resolution.
   };
 
   enum DnsProcessingState {
       // When processed by our prefetching system, the states are:
       PENDING,       // Constructor has completed.
-      QUEUED,        // In name queue but not yet being resolved.
-      ASSIGNED,      // Being resolved (or being reset to earlier state)
+      QUEUED,        // In prefetch queue but not yet being resolved.
+      ASSIGNED,      // Currently being processed.
       ASSIGNED_BUT_MARKED,  // Needs to be deleted as soon as it's resolved.
-      FOUND,         // DNS resolution completed.
-      NO_SUCH_NAME,  // DNS resolution completed.
+      FOUND,         // DNS prefetch search completed.
+      NO_SUCH_NAME,  // DNS prefetch search completed.
       // When processed by the network stack during navigation, the states are:
       STARTED,               // Resolution has begun for a navigation.
       FINISHED,              // Resolution has completed for a navigation.
       FINISHED_UNRESOLVED};  // No resolution found, so navigation will fail.
   static const base::TimeDelta kMaxNonNetworkDnsLookupDuration;
   // The number of OS cache entries we can guarantee(?) before cache eviction
   // might likely take place.
   static const int kMaxGuaranteedCacheSize = 50;
 
   typedef std::vector<DnsHostInfo> DnsInfoTable;
 
   static const base::TimeDelta kNullDuration;
 
   // DnsHostInfo are usually made by the default constructor during
   // initializing of the DnsMaster's map (of info for Hostnames).
   DnsHostInfo()
       : state_(PENDING),
-        old_prequeue_state_(state_),
         resolve_duration_(kNullDuration),
         queue_duration_(kNullDuration),
         benefits_remaining_(),
         sequence_number_(0),
         motivation_(NO_PREFETCH_MOTIVATION),
         was_linked_(false) {
   }
 
   ~DnsHostInfo() {}
 
   // NeedDnsUpdate decides, based on our internal info,
   // if it would be valuable to attempt to update (prefectch)
   // DNS data for hostname.  This decision is based
   // on how recently we've done DNS prefetching for hostname.
   bool NeedsDnsUpdate(const std::string& hostname);
 
   static void set_cache_expiration(base::TimeDelta time);
 
   // The prefetching lifecycle.
   void SetQueuedState(ResolutionMotivation motivation);
   void SetAssignedState();
-  void RemoveFromQueue();
   void SetPendingDeleteState();
   void SetFoundState();
   void SetNoSuchNameState();
   // The actual browsing resolution lifecycle.
   void SetStartedState();
   void SetFinishedState(bool was_resolved);
 
   // Finish initialization. Must only be called once.
   void SetHostname(const std::string& hostname);
 
@@ skipping 42 matching lines @@
   // Record why we created, or have updated (reqested pre-resolution) of this
   // instance.
   void SetMotivation(ResolutionMotivation motivation);
 
   // Helper function for about:dns printing.
   std::string GetAsciiMotivation() const;
 
   // The next declaration is non-const to facilitate testing.
   static base::TimeDelta kCacheExpirationDuration;
 
-  // The current state of this instance.
   DnsProcessingState state_;
-
-  // Record the state prior to going to a queued state, in case we have to back
-  // out of the queue.
-  DnsProcessingState old_prequeue_state_;
-
   std::string hostname_;  // Hostname for this info.
 
   // When was last state changed (usually lookup completed).
   base::TimeTicks time_;
   // Time needed for DNS to resolve.
   base::TimeDelta resolve_duration_;
   // Time spent in queue.
   base::TimeDelta queue_duration_;
   // Unused potential benefits of a prefetch.
   base::TimeDelta benefits_remaining_;
@@ skipping 13 matching lines @@
   std::string referring_hostname_;
 
   // We put these objects into a std::map, and hence we
   // need some "evil" constructors.
   // DISALLOW_COPY_AND_ASSIGN(DnsHostInfo);
 };
 
 }  // namespace chrome_browser_net
 
 #endif  // CHROME_BROWSER_NET_DNS_HOST_INFO_H_