Don't preresolve DNS if a fixed proxy configuration is in place.

chrome/browser/net/predictor.h

 // Copyright (c) 2012 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 Predictor object is instantiated once in the browser process, and manages
 // both preresolution of hostnames, as well as TCP/IP preconnection to expected
 // subresources.
 // Most hostname lists are provided by the renderer processes, and include URLs
 // that *might* be used in the near future by the browsing user.  One goal of
 // this class is to cause the underlying DNS structure to lookup a hostname
@@ skipping 31 matching lines @@
 class ProfileIOData;
 
 namespace base {
 class ListValue;
 class WaitableEvent;
 }
 
 namespace net {
 class HostResolver;
 class SSLConfigService;
+class ProxyService;
 class TransportSecurityState;
 class URLRequestContextGetter;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 namespace chrome_browser_net {
 
@@ skipping 249 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, ShutdownWhenResolutionIsPendingTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, SingleLookupTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, ConcurrentLookupTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, MassiveConcurrentLookupTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, PriorityQueuePushPopTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, PriorityQueueReorderTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, ReferrerSerializationTrimTest);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, SingleLookupTestWithDisabledAdvisor);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, SingleLookupTestWithEnabledAdvisor);
   FRIEND_TEST_ALL_PREFIXES(PredictorTest, TestSimplePreconnectAdvisor);
+  FRIEND_TEST_ALL_PREFIXES(PredictorTest, NoProxyService);
+  FRIEND_TEST_ALL_PREFIXES(PredictorTest, ProxyDefinitelyEnabled);
+  FRIEND_TEST_ALL_PREFIXES(PredictorTest, ProxyDefinitelyNotEnabled);
+  FRIEND_TEST_ALL_PREFIXES(PredictorTest, ProxyMaybeEnabled);
   friend class WaitForResolutionHelper;  // For testing.
 
   class LookupRequest;
 
   // A simple priority queue for handling host names.
   // Some names that are queued up have |motivation| that requires very rapid
   // handling.  For example, a sub-resource name lookup MUST be done before the
   // actual sub-resource is fetched.  In contrast, a name that was speculatively
   // noted in a page has to be resolved before the user "gets around to"
   // clicking on a link.  By tagging (with a motivation) each push we make into
@@ skipping 163 matching lines @@
   // If it does not process all the URLs in that vector, it posts a task to
   // continue with them shortly (i.e., it yeilds and continues).
   void IncrementalTrimReferrers(bool trim_all_now);
 
   // If a proxy advisor is defined, let it know that |url| will be prefetched or
   // preconnected to.
   void AdviseProxyOnIOThread(const GURL& url,
                              UrlInfo::ResolutionMotivation motivation,
                              bool is_preconnect);
 
+  // If we can determine immediately (i.e. synchronously) that requests to this
+  // URL would likely go through a proxy, then return true.  Otherwise, return
+  // false. This is used to avoid issuing DNS requests when a fixed proxy
+  // configuration is in place, which improves efficiency, and is also important
+  // if the unproxied DNS may contain incorrect entries.
+  bool WouldLikelyProxyURL(const GURL& url);
+
   // Applies the HSTS redirect for |url|, if any.
   GURL GetHSTSRedirectOnIOThread(const GURL& url);
 
   // ------------- End IO thread methods.
 
   scoped_ptr<InitialObserver> initial_observer_;
 
   // Reference to URLRequestContextGetter from the Profile which owns the
   // predictor. Used by Preconnect.
   scoped_refptr<net::URLRequestContextGetter> url_request_context_getter_;
@@ skipping 37 matching lines @@
   // The host resolver we warm DNS entries for.
   net::HostResolver* host_resolver_;
 
   // The TransportSecurityState instance we query HSTS redirects from.
   net::TransportSecurityState* transport_security_state_;
 
   // The SSLConfigService we query SNI support from (used in querying HSTS
   // redirects).
   net::SSLConfigService* ssl_config_service_;
 
+  // The ProxyService, used to determine whether preresolve is useful.
+  net::ProxyService* proxy_service_;
+
   // Are we currently using preconnection, rather than just DNS resolution, for
   // subresources and omni-box search URLs.
   // This is false if and only if disabled by a command line switch.
   const bool preconnect_enabled_;
 
   // Most recent suggestion from Omnibox provided via AnticipateOmniboxUrl().
   std::string last_omnibox_host_;
 
   // The time when the last preresolve was done for last_omnibox_host_.
   base::TimeTicks last_omnibox_preresolve_;
@@ skipping 43 matching lines @@
   virtual void ShutdownOnUIThread() OVERRIDE;
  private:
   // These member functions return True for unittests.
   virtual bool CanPrefetchAndPrerender() const OVERRIDE;
   virtual bool CanPreresolveAndPreconnect() const OVERRIDE;
 };
 
 }  // namespace chrome_browser_net
 
 #endif  // CHROME_BROWSER_NET_PREDICTOR_H_