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// 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 is the global interface for the dns prefetch services. It centralizes
// initialization, along with all the callbacks etc. to connect to the browser
// process. This allows the more standard DNS prefetching services, such as
// provided by DnsMaster to be left as more generally usable code, and possibly
// be shared across multiple client projects.
#ifndef CHROME_BROWSER_NET_DNS_GLOBAL_H_
#define CHROME_BROWSER_NET_DNS_GLOBAL_H_
#include <string>
#include "base/field_trial.h"
#include "base/scoped_ptr.h"
#include "chrome/browser/autocomplete/autocomplete.h"
#include "chrome/browser/net/dns_master.h"
#include "net/base/host_resolver.h"
class PrefService;
namespace chrome_browser_net {
// Deletes |referral_list| when done.
void FinalizeDnsPrefetchInitialization(
DnsMaster* global_dns_master,
net::HostResolver::Observer* global_prefetch_observer,
const NameList& hostnames_to_prefetch,
ListValue* referral_list);
// Free all resources allocated by FinalizeDnsPrefetchInitialization. After that
// you must not call any function from this file.
void FreeDnsPrefetchResources();
// Creates the HostResolver observer for the prefetching system.
net::HostResolver::Observer* CreatePrefetchObserver();
//------------------------------------------------------------------------------
// Global APIs relating to Prefetching in browser
void EnableDnsPrefetch(bool enable);
void RegisterPrefs(PrefService* local_state);
void RegisterUserPrefs(PrefService* user_prefs);
// Renderer bundles up list and sends to this browser API via IPC.
void DnsPrefetchList(const NameList& hostnames);
// This API is used by the autocomplete popup box (as user types).
// This will either preresolve the domain name, or possibly preconnect creating
// an open TCP/IP connection to the host.
void DnsPrefetchUrl(const GURL& url, bool preconnectable);
// When displaying info in about:dns, the following API is called.
void DnsPrefetchGetHtmlInfo(std::string* output);
//------------------------------------------------------------------------------
void SaveDnsPrefetchStateForNextStartupAndTrim(PrefService* prefs);
// Helper class to handle global init and shutdown.
class DnsGlobalInit {
public:
// Too many concurrent lookups negate benefits of prefetching by trashing
// the OS cache before all resource loading is complete.
// This is the default.
static const size_t kMaxPrefetchConcurrentLookups;
// When prefetch requests are queued beyond some period of time, then the
// system is congested, and we need to clear all queued requests to get out
// of that state. The following is the suggested default time limit.
static const int kMaxPrefetchQueueingDelayMs;
DnsGlobalInit(PrefService* user_prefs, PrefService* local_state,
bool preconnect_enabled);
private:
// Maintain a field trial instance when we do A/B testing.
scoped_refptr<FieldTrial> trial_;
DISALLOW_COPY_AND_ASSIGN(DnsGlobalInit);
};
} // namespace chrome_browser_net
#endif // CHROME_BROWSER_NET_DNS_GLOBAL_H_
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