Add a browsertest suite for net predictor

chrome/browser/net/predictor.cc

 // 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.
 
 #include "chrome/browser/net/predictor.h"
 
 #include <algorithm>
 #include <cmath>
 #include <set>
 #include <sstream>
@@ skipping 223 matching lines @@
   if (!CanPreresolveAndPreconnect())
     return;
 
   std::string host = url.HostNoBrackets();
   bool is_new_host_request = (host != last_omnibox_host_);
   last_omnibox_host_ = host;
 
   UrlInfo::ResolutionMotivation motivation(UrlInfo::OMNIBOX_MOTIVATED);
   base::TimeTicks now = base::TimeTicks::Now();
 
-  if (preconnect_enabled_) {
+  if (PreconnectEnabled()) {
     if (preconnectable && !is_new_host_request) {
       ++consecutive_omnibox_preconnect_count_;
       // The omnibox suggests a search URL (for which we can preconnect) after
       // one or two characters are typed, even though such typing often (1 in
       // 3?) becomes a real URL.  This code waits till is has more evidence of a
       // preconnectable URL (search URL) before forming a preconnection, so as
       // to reduce the useless preconnect rate.
       // Perchance this logic should be pushed back into the omnibox, where the
       // actual characters typed, such as a space, can better forcast whether
       // we need to search/preconnect or not.  By waiting for at least 4
@@ skipping 43 matching lines @@
       BrowserThread::IO,
       FROM_HERE,
       base::Bind(&Predictor::Resolve, base::Unretained(this),
                  CanonicalizeUrl(url), motivation));
 }
 
 void Predictor::PreconnectUrlAndSubresources(const GURL& url,
     const GURL& first_party_for_cookies) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI) ||
          BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (!predictor_enabled_ || !preconnect_enabled_ ||
-      !url.is_valid() || !url.has_host())
+  if (!predictor_enabled_ || !PreconnectEnabled() || !url.is_valid() ||
+      !url.has_host())
     return;
   if (!CanPreresolveAndPreconnect())
     return;
 
   UrlInfo::ResolutionMotivation motivation(UrlInfo::EARLY_LOAD_MOTIVATED);
   const int kConnectionsNeeded = 1;
   PreconnectUrl(CanonicalizeUrl(url), first_party_for_cookies, motivation,
                 kConnectionsNeeded, kAllowCredentialsOnPreconnectByDefault);
   PredictFrameSubresources(url.GetWithEmptyPath(), first_party_for_cookies);
 }
@@ skipping 145 matching lines @@
 void Predictor::LearnFromNavigation(const GURL& referring_url,
                                     const GURL& target_url) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!predictor_enabled_ || !CanPreresolveAndPreconnect())
     return;
   DCHECK_EQ(referring_url, Predictor::CanonicalizeUrl(referring_url));
   DCHECK_NE(referring_url, GURL::EmptyGURL());
   DCHECK_EQ(target_url, Predictor::CanonicalizeUrl(target_url));
   DCHECK_NE(target_url, GURL::EmptyGURL());
 
+  if (observer_)
+    observer_->OnLearnFromNavigation(referring_url, target_url);
   referrers_[referring_url].SuggestHost(target_url);
   // Possibly do some referrer trimming.
   TrimReferrers();
 }
 
 //-----------------------------------------------------------------------------
 // This section supports the about:dns page.
 
 void Predictor::PredictorGetHtmlInfo(Predictor* predictor,
                                      std::string* output) {
@@ skipping 486 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK_EQ(url.GetWithEmptyPath(), url);
   Referrers::iterator it = referrers_.find(url);
   if (referrers_.end() == it) {
     // Only when we don't know anything about this url, make 2 connections
     // available.  We could do this completely via learning (by prepopulating
     // the referrer_ list with this expected value), but it would swell the
     // size of the list with all the "Leaf" nodes in the tree (nodes that don't
     // load any subresources).  If we learn about this resource, we will instead
     // provide a more carefully estimated preconnection count.
-    if (preconnect_enabled_) {
+    if (PreconnectEnabled()) {
       PreconnectUrlOnIOThread(url, first_party_for_cookies,
                               UrlInfo::SELF_REFERAL_MOTIVATED,
                               kAllowCredentialsOnPreconnectByDefault, 2);
     }
     return;
   }
 
   Referrer* referrer = &(it->second);
   referrer->IncrementUseCount();
   const UrlInfo::ResolutionMotivation motivation =
       UrlInfo::LEARNED_REFERAL_MOTIVATED;
   for (Referrer::iterator future_url = referrer->begin();
        future_url != referrer->end(); ++future_url) {
     SubresourceValue evalution(TOO_NEW);
     double connection_expectation = future_url->second.subresource_use_rate();
     UMA_HISTOGRAM_CUSTOM_COUNTS("Net.PreconnectSubresourceExpectation",
                                 static_cast<int>(connection_expectation * 100),
                                 10, 5000, 50);
     future_url->second.ReferrerWasObserved();
-    if (preconnect_enabled_ &&
+    if (PreconnectEnabled() &&
         connection_expectation > kPreconnectWorthyExpectedValue) {
       evalution = PRECONNECTION;
       future_url->second.IncrementPreconnectionCount();
       int count = static_cast<int>(std::ceil(connection_expectation));
       if (url.host_piece() == future_url->first.host_piece())
         ++count;
       PreconnectUrlOnIOThread(future_url->first, first_party_for_cookies,
                               motivation,
                               kAllowCredentialsOnPreconnectByDefault, count);
     } else if (connection_expectation > kDNSPreresolutionWorthyExpectedValue) {
@@ skipping 197 matching lines @@
   url::Replacements<char> replacements;
   const char kNewScheme[] = "https";
   replacements.SetScheme(kNewScheme, url::Component(0, strlen(kNewScheme)));
   return url.ReplaceComponents(replacements);
 }
 
 // ---------------------- End IO methods. -------------------------------------
 
 //-----------------------------------------------------------------------------
 
+bool Predictor::PreconnectEnabled() const {
+  base::AutoLock lock(preconnect_enabled_lock_);
+  return preconnect_enabled_;
+}
+
+void Predictor::SetPreconnectEnabledForTest(bool preconnect_enabled) {
+  base::AutoLock lock(preconnect_enabled_lock_);
+  preconnect_enabled_ = preconnect_enabled;
+}
+
 Predictor::HostNameQueue::HostNameQueue() {
 }
 
 Predictor::HostNameQueue::~HostNameQueue() {
 }
 
 void Predictor::HostNameQueue::Push(const GURL& url,
     UrlInfo::ResolutionMotivation motivation) {
   switch (motivation) {
     case UrlInfo::STATIC_REFERAL_MOTIVATED:
@@ skipping 118 matching lines @@
 }
 
 void SimplePredictor::ShutdownOnUIThread() {
   SetShutdown(true);
 }
 
 bool SimplePredictor::CanPrefetchAndPrerender() const { return true; }
 bool SimplePredictor::CanPreresolveAndPreconnect() const { return true; }
 
 }  // namespace chrome_browser_net