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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "chrome/browser/net/preconnect.h"
      6 
      7 #include "base/logging.h"
      8 #include "base/metrics/histogram.h"
      9 #include "chrome/browser/profiles/profile.h"
     10 #include "content/browser/browser_thread.h"
     11 #include "net/base/net_log.h"
     12 #include "net/base/ssl_config_service.h"
     13 #include "net/http/http_network_session.h"
     14 #include "net/http/http_request_info.h"
     15 #include "net/http/http_stream_factory.h"
     16 #include "net/http/http_transaction_factory.h"
     17 #include "net/url_request/url_request_context.h"
     18 #include "net/url_request/url_request_context_getter.h"
     19 
     20 namespace chrome_browser_net {
     21 
     22 void PreconnectOnUIThread(
     23     const GURL& url,
     24     UrlInfo::ResolutionMotivation motivation,
     25     int count) {
     26   // Prewarm connection to Search URL.
     27   BrowserThread::PostTask(
     28       BrowserThread::IO,
     29       FROM_HERE,
     30       NewRunnableFunction(PreconnectOnIOThread, url, motivation,
     31                           count));
     32   return;
     33 }
     34 
     35 
     36 void PreconnectOnIOThread(
     37     const GURL& url,
     38     UrlInfo::ResolutionMotivation motivation,
     39     int count) {
     40   net::URLRequestContextGetter* getter = Profile::GetDefaultRequestContext();
     41   if (!getter)
     42     return;
     43   if (!BrowserThread::CurrentlyOn(BrowserThread::IO)) {
     44     LOG(DFATAL) << "This must be run only on the IO thread.";
     45     return;
     46   }
     47 
     48   // We are now commited to doing the async preconnection call.
     49   UMA_HISTOGRAM_ENUMERATION("Net.PreconnectMotivation", motivation,
     50                             UrlInfo::MAX_MOTIVATED);
     51 
     52   net::URLRequestContext* context = getter->GetURLRequestContext();
     53   net::HttpTransactionFactory* factory = context->http_transaction_factory();
     54   net::HttpNetworkSession* session = factory->GetSession();
     55 
     56   net::HttpRequestInfo request_info;
     57   request_info.url = url;
     58   request_info.method = "GET";
     59   request_info.extra_headers.SetHeader(net::HttpRequestHeaders::kUserAgent,
     60                                        context->GetUserAgent(url));
     61   // It almost doesn't matter whether we use net::LOWEST or net::HIGHEST
     62   // priority here, as we won't make a request, and will surrender the created
     63   // socket to the pool as soon as we can.  However, we would like to mark the
     64   // speculative socket as such, and IF we use a net::LOWEST priority, and if
     65   // a navigation asked for a socket (after us) then it would get our socket,
     66   // and we'd get its later-arriving socket, which might make us record that
     67   // the speculation didn't help :-/.  By using net::HIGHEST, we ensure that
     68   // a socket is given to us if "we asked first" and this allows us to mark it
     69   // as speculative, and better detect stats (if it gets used).
     70   // TODO(jar): histogram to see how often we accidentally use a previously-
     71   // unused socket, when a previously used socket was available.
     72   request_info.priority = net::HIGHEST;
     73 
     74   // Translate the motivation from UrlRequest motivations to HttpRequest
     75   // motivations.
     76   switch (motivation) {
     77     case UrlInfo::OMNIBOX_MOTIVATED:
     78       request_info.motivation = net::HttpRequestInfo::OMNIBOX_MOTIVATED;
     79       break;
     80     case UrlInfo::LEARNED_REFERAL_MOTIVATED:
     81       request_info.motivation = net::HttpRequestInfo::PRECONNECT_MOTIVATED;
     82       break;
     83     case UrlInfo::SELF_REFERAL_MOTIVATED:
     84     case UrlInfo::EARLY_LOAD_MOTIVATED:
     85       request_info.motivation = net::HttpRequestInfo::EARLY_LOAD_MOTIVATED;
     86       break;
     87     default:
     88       // Other motivations should never happen here.
     89       NOTREACHED();
     90       break;
     91   }
     92 
     93   // Setup the SSL Configuration.
     94   net::SSLConfig ssl_config;
     95   session->ssl_config_service()->GetSSLConfig(&ssl_config);
     96   if (session->http_stream_factory()->next_protos())
     97     ssl_config.next_protos = *session->http_stream_factory()->next_protos();
     98 
     99   // All preconnects should perform EV certificate verification.
    100   ssl_config.verify_ev_cert = true;
    101 
    102   net::HttpStreamFactory* http_stream_factory = session->http_stream_factory();
    103   http_stream_factory->PreconnectStreams(
    104       count, request_info, ssl_config, net::BoundNetLog());
    105 }
    106 
    107 }  // namespace chrome_browser_net
    108