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

chrome/browser/net/predictor.h

Index: chrome/browser/net/predictor.h
diff --git a/chrome/browser/net/predictor.h b/chrome/browser/net/predictor.h
index 85b8d1894cd031b11c8304931530d0df54cfec86..d9df615d670efc33b0cc4c9546e1b3f460dfa031 100644
--- a/chrome/browser/net/predictor.h
+++ b/chrome/browser/net/predictor.h
@@ -49,6 +49,7 @@ class WaitableEvent;
 namespace net {
 class HostResolver;
 class SSLConfigService;
+class ProxyService;
 class TransportSecurityState;
 class URLRequestContextGetter;
 }
@@ -318,6 +319,10 @@ class Predictor {
   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;
@@ -501,6 +506,13 @@ class Predictor {
                              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);
 
@@ -558,6 +570,9 @@ class Predictor {
   // 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.