Support both preconnection, and pre-resolution for subresources...

chrome/browser/io_thread.cc

 // Copyright (c) 2010 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/io_thread.h"
 #include "base/command_line.h"
 #include "base/leak_tracker.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_thread.h"
@@ skipping 318 matching lines @@
 
   chrome_browser_net::EnablePredictor(prefetching_enabled);
 
   predictor_ = new chrome_browser_net::Predictor(
       globals_->host_resolver,
       max_dns_queue_delay,
       max_concurrent,
       preconnect_enabled);
   predictor_->AddRef();
 
-  // TODO(jar): Until connection notification and DNS observation handling are
-  // properly combined into a learning model, we'll only use one observation
-  // mechanism or the other.
-  if (preconnect_enabled) {
-    DCHECK(!speculative_interceptor_);
-    speculative_interceptor_ = new chrome_browser_net::ConnectInterceptor;
-  } else {
-    DCHECK(!prefetch_observer_);
-    prefetch_observer_ = chrome_browser_net::CreateResolverObserver();
-    globals_->host_resolver->AddObserver(prefetch_observer_);
-  }
+  // Speculative_interceptor_ is used to predict subresource usage.
+  DCHECK(!speculative_interceptor_);
+  speculative_interceptor_ = new chrome_browser_net::ConnectInterceptor;
+
+  // TODO(jar): We can completely replace prefetch_observer with
+  // speculative_interceptor.
+  // Prefetch_observer is used to monitor initial resolutions.
+  DCHECK(!prefetch_observer_);
+  prefetch_observer_ = chrome_browser_net::CreateResolverObserver();
+  globals_->host_resolver->AddObserver(prefetch_observer_);
 
   FinalizePredictorInitialization(
       predictor_, prefetch_observer_, startup_urls, referral_list);
 }
 
 void IOThread::ChangedToOnTheRecordOnIOThread() {
   DCHECK(ChromeThread::CurrentlyOn(ChromeThread::IO));
 
   if (predictor_) {
     // Destroy all evidence of our OTR session.
     predictor_->Predictor::DiscardAllResults();
   }
 
   // Clear the host cache to avoid showing entries from the OTR session
   // in about:net-internals.
   if (globals_->host_resolver->GetAsHostResolverImpl()) {
     net::HostCache* host_cache =
         globals_->host_resolver.get()->GetAsHostResolverImpl()->cache();
     if (host_cache)
       host_cache->clear();
   }
   // Clear all of the passively logged data.
   // TODO(eroman): this is a bit heavy handed, really all we need to do is
   //               clear the data pertaining to off the record context.
   globals_->net_log->passive_collector()->Clear();
 }