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

chrome/browser/net/dns_master.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.
 
 #include "chrome/browser/net/dns_master.h"
 
 #include <algorithm>
 #include <set>
 #include <sstream>
 
@@ skipping 17 matching lines @@
                 net::HostResolver* host_resolver,
                 const std::string& hostname)
       : ALLOW_THIS_IN_INITIALIZER_LIST(
           net_callback_(this, &LookupRequest::OnLookupFinished)),
         master_(master),
         hostname_(hostname),
         resolver_(host_resolver) {
   }
 
   bool Start() {
-    const int result = resolver_.Resolve(hostname_, 80, &addresses_,
-                                         &net_callback_);
+    // Port doesn't really matter.
+    net::HostResolver::RequestInfo resolve_info(hostname_, 80);
+
+    // Make a note that this is a speculative resolve request. This allows us
+    // to separate it from real navigations in the observer's callback, and
+    // lets the HostResolver know it can de-prioritize it.
+    resolve_info.set_is_speculative(true);
+
+    const int result = resolver_.Resolve(
+        resolve_info, &addresses_, &net_callback_);
     return (result == net::ERR_IO_PENDING);
   }
 
  private:
   void OnLookupFinished(int result) {
     master_->OnLookupFinished(this, hostname_, result == net::OK);
   }
 
   // HostResolver will call us using this callback when resolution is complete.
   net::CompletionCallbackImpl<LookupRequest> net_callback_;
@@ skipping 541 matching lines @@
     std::string hostname(rush_queue_.front());
     rush_queue_.pop();
     return hostname;
   }
   std::string hostname(background_queue_.front());
   background_queue_.pop();
   return hostname;
 }
 
 }  // namespace chrome_browser_net