Add field trial to extend prerender expiration to 5 minutes.

Review URL: http://codereview.chromium.org/9463026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@124777 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/prerender/prerender_field_trial.cc

@@ -43,30 +43,41 @@ void SetupPrefetchFieldTrial() {
 
 void SetupPrerenderFieldTrial() {
   base::FieldTrial::Probability divisor = 1000;
-  base::FieldTrial::Probability exp1_probability = 200;
-  base::FieldTrial::Probability control1_probability = 200;
-  base::FieldTrial::Probability no_use1_probability = 100;
-  base::FieldTrial::Probability exp2_probability = 200;
-  base::FieldTrial::Probability control2_probability = 200;
-  base::FieldTrial::Probability no_use2_probability = 100;
+
+  base::FieldTrial::Probability exp1_probability = 166;
+  base::FieldTrial::Probability exp1_5min_ttl_probability = 83;
+  base::FieldTrial::Probability control1_probability = 166;
+  base::FieldTrial::Probability no_use1_probability = 83;
+
+  base::FieldTrial::Probability exp2_probability = 167;
+  base::FieldTrial::Probability exp2_5min_ttl_probability = 84;
+  base::FieldTrial::Probability control2_probability = 167;
+  base::FieldTrial::Probability no_use2_probability = 84;
+
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
-    exp1_probability = 495;
+    exp1_probability = 490;
+    exp1_5min_ttl_probability = 5;
     control1_probability = 5;
     no_use1_probability = 0;
-    exp2_probability = 495;
+    exp2_probability = 490;
+    exp2_5min_ttl_probability = 5;
     control2_probability = 5;
     no_use2_probability = 0;
   }
-  CHECK_EQ(divisor, exp1_probability + control1_probability +
-           no_use1_probability + exp2_probability +
-           control2_probability + no_use2_probability);
+  CHECK_EQ(divisor, exp1_probability + exp1_5min_ttl_probability +
+           control1_probability + no_use1_probability + exp2_probability +
+           exp2_5min_ttl_probability + control2_probability +
+           no_use2_probability);
   scoped_refptr<base::FieldTrial> trial(
       new base::FieldTrial("Prerender", divisor,
                            "ContentPrefetchPrerender1", 2012, 6, 30));
 
   const int kExperiment1Group = trial->kDefaultGroupNumber;
+  const int kExperiment15minTTLGroup =
+      trial->AppendGroup("ContentPrefetchPrerenderExp5minTTL1",
+                         exp1_5min_ttl_probability);
   const int kControl1Group =
       trial->AppendGroup("ContentPrefetchPrerenderControl1",
                          control1_probability);
@@ -76,6 +87,9 @@ void SetupPrerenderFieldTrial() {
   const int kExperiment2Group =
       trial->AppendGroup("ContentPrefetchPrerender2",
                          exp2_probability);
+  const int kExperiment25minTTLGroup =
+      trial->AppendGroup("ContentPrefetchPrerenderExp5minTTL2",
+                         exp2_5min_ttl_probability);
   const int kControl2Group =
       trial->AppendGroup("ContentPrefetchPrerenderControl2",
                          control2_probability);
@@ -87,6 +101,10 @@ void SetupPrerenderFieldTrial() {
       trial_group == kExperiment2Group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
+  } else if (trial_group == kExperiment15minTTLGroup ||
+             trial_group == kExperiment25minTTLGroup) {
+    PrerenderManager::SetMode(
+        PrerenderManager::PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP);
   } else if (trial_group == kControl1Group ||
              trial_group == kControl2Group) {
     PrerenderManager::SetMode(

chrome/browser/prerender/prerender_manager.cc

@@ -415,7 +415,7 @@ bool PrerenderManager::MaybeUsePrerenderedPage(WebContents* web_contents,
   if (!prerender_contents->load_start_time().is_null()) {
     histograms_->RecordTimeUntilUsed(GetCurrentTimeTicks() -
                                      prerender_contents->load_start_time(),
-                                     config_.max_age);
+                                     GetMaxAge());
   }
 
   histograms_->RecordPerSessionCount(++prerenders_per_session_count_);
@@ -591,10 +591,7 @@ void PrerenderManager::SetMode(PrerenderManagerMode mode) {
 
 // static
 bool PrerenderManager::IsPrerenderingPossible() {
-  return GetMode() == PRERENDER_MODE_ENABLED ||
-         GetMode() == PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP ||
-         GetMode() == PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP ||
-         GetMode() == PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP;
+  return GetMode() != PRERENDER_MODE_DISABLED;
 }
 
 // static
@@ -724,10 +721,14 @@ DictionaryValue* PrerenderManager::GetAsValue() const {
   dict_value->SetBoolean("enabled", enabled_);
   dict_value->SetBoolean("omnibox_enabled", IsOmniboxEnabled(profile_));
   // If prerender is disabled via a flag this method is not even called.
+  std::string enabled_note;
   if (IsControlGroup())
-    dict_value->SetString("disabled_reason", "(Disabled for testing)");
+    enabled_note += "(Control group: Not actually prerendering) ";
   if (IsNoUseGroup())
-    dict_value->SetString("disabled_reason", "(Not using prerendered pages)");
+    enabled_note += "(No-use group: Not swapping in prerendered pages) ";
+  if (GetMode() == PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP)
+    enabled_note += "(5 min TTL group: Extended prerender eviction to 5 mins) ";
+  dict_value->SetString("enabled_note", enabled_note);
   return dict_value;
 }
 
@@ -984,10 +985,15 @@ void PrerenderManager::PostCleanupTask() {
                  weak_factory_.GetWeakPtr()));
 }
 
+base::TimeDelta PrerenderManager::GetMaxAge() const {
+  return (GetMode() == PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP ?
+      base::TimeDelta::FromSeconds(300) : config_.max_age);
+}
+
 bool PrerenderManager::IsPrerenderElementFresh(const base::Time start) const {
   DCHECK(CalledOnValidThread());
   base::Time now = GetCurrentTime();
-  return (now - start < config_.max_age);
+  return (now - start < GetMaxAge());
 }
 
 void PrerenderManager::DeleteOldEntries() {

chrome/browser/prerender/prerender_manager.h

@@ -69,6 +69,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
     PRERENDER_MODE_ENABLED,
     PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP,
     PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP,
+    PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP,
     PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP,
     PRERENDER_MODE_MAX
   };
@@ -317,6 +318,7 @@ class PrerenderManager : public base::SupportsWeakPtr<PrerenderManager>,
   // automatically be cancelled.
   void PostCleanupTask();
 
+  base::TimeDelta GetMaxAge() const;
   bool IsPrerenderElementFresh(const base::Time start) const;
   void DeleteOldEntries();
   virtual base::Time GetCurrentTime() const;

chrome/browser/prerender/prerender_manager_unittest.cc

@@ -292,8 +292,8 @@ TEST_F(PrerenderManagerTest, ExpireTest) {
   EXPECT_TRUE(prerender_manager()->AddSimplePrerender(url));
   EXPECT_EQ(null, prerender_manager()->next_prerender_contents());
   EXPECT_TRUE(prerender_contents->has_started());
-  prerender_manager()->AdvanceTime(prerender_manager()->config().max_age
-                                   + base::TimeDelta::FromSeconds(1));
+  prerender_manager()->AdvanceTime(prerender_manager()->GetMaxAge() +
+                                   base::TimeDelta::FromSeconds(1));
   ASSERT_EQ(null, prerender_manager()->GetEntry(url));
 }
 

chrome/browser/resources/net_internals/prerender_view.js

@@ -57,9 +57,9 @@ var PrerenderView = (function() {
       if (prerenderInfo && ('enabled' in prerenderInfo)) {
         this.prerenderEnabledSpan_.textContent =
             prerenderInfo.enabled.toString();
-        if (prerenderInfo.disabled_reason) {
+        if (prerenderInfo.enabled_note) {
           this.prerenderEnabledSpan_.textContent +=
-              ' ' + prerenderInfo.disabled_reason;
+              ' ' + prerenderInfo.enabled_note;
         }
       }