Revert "Clean up dns prefetch code, and also port it."

net/base/host_resolver.cc

 // 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.
 
 #include "net/base/host_resolver.h"
 
 #if defined(OS_WIN)
 #include <ws2tcpip.h>
 #include <wspiapi.h>  // Needed for Win2k compat.
 #elif defined(OS_POSIX)
@@ skipping 45 matching lines @@
   if (mapper) {
     rv = HostResolverProc(mapper->Map(host), port, out);
   } else {
     rv = HostResolverProc(host, port, out);
   }
   return rv;
 }
 
 //-----------------------------------------------------------------------------
 
-class HostResolver::Request
-    : public base::RefCountedThreadSafe<HostResolver::Request>,
-      public MessageLoop::DestructionObserver {
+class HostResolver::Request :
+    public base::RefCountedThreadSafe<HostResolver::Request> {
  public:
   Request(HostResolver* resolver,
           const std::string& host,
           const std::string& port,
           AddressList* addresses,
           CompletionCallback* callback)
       : host_(host),
         port_(port),
         resolver_(resolver),
         addresses_(addresses),
         callback_(callback),
         origin_loop_(MessageLoop::current()),
         host_mapper_(host_mapper),
         error_(OK),
         results_(NULL) {
-    MessageLoop::current()->AddDestructionObserver(this);
   }
 
-  virtual ~Request() {
+  ~Request() {
     if (results_)
       freeaddrinfo(results_);
   }
 
   void DoLookup() {
     // Running on the worker thread
     error_ = ResolveAddrInfo(host_mapper_, host_, port_, &results_);
 
     Task* reply = NewRunnableMethod(this, &Request::DoCallback);
 
     // The origin loop could go away while we are trying to post to it, so we
     // need to call its PostTask method inside a lock.  See ~HostResolver.
     {
       AutoLock locked(origin_loop_lock_);
       if (origin_loop_) {
         origin_loop_->PostTask(FROM_HERE, reply);
         reply = NULL;
       }
     }
 
     // Does nothing if it got posted.
     delete reply;
   }
 
   void DoCallback() {
     // Running on the origin thread.
     DCHECK(error_ || results_);
 
-    {
-      AutoLock locked(origin_loop_lock_);
-      if (origin_loop_)
-        origin_loop_->RemoveDestructionObserver(this);
-    }
-
     // We may have been cancelled!
     if (!resolver_)
       return;
 
     if (!error_) {
       addresses_->Adopt(results_);
       results_ = NULL;
     }
 
     // Drop the resolver's reference to us.  Do this before running the
     // callback since the callback might result in the resolver being
     // destroyed.
     resolver_->request_ = NULL;
 
     callback_->Run(error_);
   }
 
   void Cancel() {
     resolver_ = NULL;
 
     AutoLock locked(origin_loop_lock_);
     origin_loop_ = NULL;
   }
 
-  virtual void WillDestroyCurrentMessageLoop() {
-    AutoLock locked(origin_loop_lock_);
-    origin_loop_ = NULL;
-  }
-
  private:
   // Set on the origin thread, read on the worker thread.
   std::string host_;
   std::string port_;
 
   // Only used on the origin thread (where Resolve was called).
   HostResolver* resolver_;
   AddressList* addresses_;
   CompletionCallback* callback_;
 
@@ skipping 14 matching lines @@
 
 //-----------------------------------------------------------------------------
 
 HostResolver::HostResolver() {
 #if defined(OS_WIN)
   EnsureWinsockInit();
 #endif
 }
 
 HostResolver::~HostResolver() {
-  if (request_) {
+  if (request_)
     request_->Cancel();
-    MessageLoop::current()->RemoveDestructionObserver(request_.get());
-  }
 }
 
 int HostResolver::Resolve(const std::string& hostname, int port,
                           AddressList* addresses,
                           CompletionCallback* callback) {
   DCHECK(!request_) << "resolver already in use";
 
   const std::string& port_str = IntToString(port);
 
   // Do a synchronous resolution.
   if (!callback) {
     struct addrinfo* results;
     int rv = ResolveAddrInfo(host_mapper, hostname, port_str, &results);
     if (rv == OK)
       addresses->Adopt(results);
     return rv;
   }
 
   request_ = new Request(this, hostname, port_str, addresses, callback);
 
   // Dispatch to worker thread...
   if (!WorkerPool::PostTask(FROM_HERE,
           NewRunnableMethod(request_.get(), &Request::DoLookup), true)) {
     NOTREACHED();
-    MessageLoop::current()->RemoveDestructionObserver(request_.get());
     request_ = NULL;
     return ERR_FAILED;
   }
 
   return ERR_IO_PENDING;
 }
 
 }  // namespace net