* Move the global "DnsResolutionObserver" code depended on by DNS prefetcher,...

net/base/dns_resolution_observer.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.
-
-// This file supports network stack independent notification of progress
-// towards resolving a hostname.
-
-#include "net/base/dns_resolution_observer.h"
-
-#include <string>
-
-#include "base/logging.h"
-
-namespace net {
-
-static DnsResolutionObserver* dns_resolution_observer;
-
-void AddDnsResolutionObserver(DnsResolutionObserver* new_observer) {
-  if (new_observer == dns_resolution_observer)
-    return;  // Facilitate unit tests that init/teardown repeatedly.
-  DCHECK(!dns_resolution_observer);
-  dns_resolution_observer = new_observer;
-}
-
-DnsResolutionObserver* RemoveDnsResolutionObserver() {
-  // We really need to check that the entire network subsystem is shutting down,
-  // and hence no additional calls can even *possibly* still be lingering in the
-  // notification path that includes our observer.  Until we have a way to
-  // really assert that fact, we will outlaw the calling of this function.
-  // Darin suggested that the caller use a static initializer for the observer,
-  // so that it can safely be destroyed after process termination, and without
-  // inducing a memory leak.
-  // Bottom line: Don't call this function!  You will crash for now.
-  CHECK(0);
-  DnsResolutionObserver* old_observer = dns_resolution_observer;
-  dns_resolution_observer = NULL;
-  return old_observer;
-}
-
-// Locking access to dns_resolution_observer is not really critical... but we
-// should test the value of dns_resolution_observer that we use.
-// Worst case, we'll get an "out of date" value... which is no big deal for the
-// DNS prefetching system (the most common (only?) observer).
-void DidStartDnsResolution(const std::string& name, void* context) {
-  DnsResolutionObserver* current_observer = dns_resolution_observer;
-  if (current_observer)
-    current_observer->OnStartResolution(name, context);
-}
-
-void DidFinishDnsResolutionWithStatus(bool was_resolved,
-                                      const GURL& referrer,
-                                      void* context) {
-  DnsResolutionObserver* current_observer = dns_resolution_observer;
-  if (current_observer) {
-    current_observer->OnFinishResolutionWithStatus(was_resolved, referrer,
-                                                   context);
-  }
-}
-
-}  // namspace net