Make three simultanious prerenders the default maximum in Canary and Dev only.

chrome/browser/prerender/prerender_field_trial.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/prerender/prerender_field_trial.h"
 
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
@@ skipping 34 matching lines @@
           2013, 6, 30, NULL));
   const int kPrefetchOnGroup = trial->AppendGroup("ContentPrefetchPrefetchOn",
                                                   prefetch_probability);
   PrerenderManager::SetIsPrefetchEnabled(trial->group() == kPrefetchOnGroup);
 }
 
 void SetupPrerenderFieldTrial() {
   const FieldTrial::Probability divisor = 1000;
 
   FieldTrial::Probability control_probability;
+  FieldTrial::Probability experiment_multi_prerender_probability;
   FieldTrial::Probability experiment_5min_ttl_probability;
   FieldTrial::Probability experiment_no_use_probability;
 
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
     // Use very conservatives and stable settings in beta and stable.
     const FieldTrial::Probability release_prerender_enabled_probability = 980;
     const FieldTrial::Probability release_control_probability = 10;
+    const FieldTrial::Probability
+        release_experiment_multi_prerender_probability = 0;
     const FieldTrial::Probability release_experiment_5min_ttl_probability = 10;
     const FieldTrial::Probability release_experiment_no_use_probability = 0;
     COMPILE_ASSERT(
         release_prerender_enabled_probability + release_control_probability +
+        release_experiment_multi_prerender_probability +
         release_experiment_5min_ttl_probability +
         release_experiment_no_use_probability == divisor,
         release_experiment_probabilities_must_equal_divisor);
 
     control_probability = release_experiment_5min_ttl_probability;
+    experiment_multi_prerender_probability =
+        release_experiment_multi_prerender_probability;
     experiment_5min_ttl_probability = release_control_probability;
     experiment_no_use_probability = release_experiment_no_use_probability;
   } else {
     // In testing channels, use more experiments and a larger control group to
     // improve quality of data.
-    const FieldTrial::Probability dev_prerender_enabled_probability = 333;
-    const FieldTrial::Probability dev_control_probability = 333;
-    const FieldTrial::Probability dev_experiment_5min_ttl_probability = 167;
-    const FieldTrial::Probability dev_experiment_no_use_probability = 167;
+    const FieldTrial::Probability dev_prerender_enabled_probability = 250;
+    const FieldTrial::Probability dev_control_probability = 250;
+    const FieldTrial::Probability
+        dev_experiment_multi_prerender_probability = 250;
+    const FieldTrial::Probability dev_experiment_5min_ttl_probability = 125;
+    const FieldTrial::Probability dev_experiment_no_use_probability = 125;
     COMPILE_ASSERT(dev_prerender_enabled_probability + dev_control_probability +
+                   dev_experiment_multi_prerender_probability +
                    dev_experiment_5min_ttl_probability +
                    dev_experiment_no_use_probability == divisor,
                    dev_experiment_probabilities_must_equal_divisor);
 
     control_probability = dev_experiment_5min_ttl_probability;
+    experiment_multi_prerender_probability =
+        dev_experiment_multi_prerender_probability;
     experiment_5min_ttl_probability = dev_control_probability;
     experiment_no_use_probability = dev_experiment_no_use_probability;
   }
 
   int prerender_enabled_group = -1;
   scoped_refptr<FieldTrial> trial(
       FieldTrialList::FactoryGetFieldTrial(
           "Prerender", divisor, "PrerenderEnabled",
           2013, 6, 30, &prerender_enabled_group));
   const int control_group =
       trial->AppendGroup("PrerenderControl",
                          control_probability);
+  const int experiment_multi_prerender_group =
+      trial->AppendGroup("PrerenderMulti",
+                         experiment_multi_prerender_probability);
   const int experiment_5_min_TTL_group =
       trial->AppendGroup("Prerender5minTTL",
                          experiment_5min_ttl_probability);
   const int experiment_no_use_group =
       trial->AppendGroup("PrerenderNoUse",
                          experiment_no_use_probability);
 
   const int trial_group = trial->group();
   if (trial_group == prerender_enabled_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
   } else if (trial_group == control_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP);
+  } else if (trial_group == experiment_multi_prerender_group) {
+    PrerenderManager::SetMode(
+        PrerenderManager::PRERENDER_MODE_EXPERIMENT_MULTI_PRERENDER_GROUP);
   } else if (trial_group == experiment_5_min_TTL_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP);
   } else if (trial_group == experiment_no_use_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP);
   } else {
     NOTREACHED();
   }
 }
@@ skipping 147 matching lines @@
     if (switch_value == switches::kSpeculativeResourcePrefetchingLearning)
       return true;
   }
 
   const int group = FieldTrialList::FindValue(
       kSpeculativePrefetchingLearningTrialName);
   return group == g_speculative_prefetching_learning_default_group_number;
 }
 
 }  // namespace prerender