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 30 matching lines @@
           "Prefetch", divisor, "ContentPrefetchPrefetchOff",
           2013, 6, 30, NULL));
   const int kPrefetchOnGroup = trial->AppendGroup("ContentPrefetchPrefetchOn",
                                                   prefetch_probability);
   PrerenderManager::SetIsPrefetchEnabled(trial->group() == kPrefetchOnGroup);
 }
 
 void SetupPrerenderFieldTrial() {
   base::FieldTrial::Probability divisor = 1000;
 
-  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 exp1_probability = 150;

[dominich, 2012/07/19 16:04:38]

I would very much like to remove half of these now that we're confident that
variance within each group is within acceptable bounds.

[gavinp, 2012/07/23 18:35:21]

I like that plan, but I figured a separate CL for cleaning this up makes more
sense. See http://codereview.chromium.org/10802062/ , which my upload rebases
on.

+  base::FieldTrial::Probability exp1_5min_ttl_probability = 67;
+  base::FieldTrial::Probability control1_probability = 150;
+  base::FieldTrial::Probability no_use1_probability = 67;
+  base::FieldTrial::Probability one_prerender1_probability = 66;

[dominich, 2012/07/19 16:04:38]

We should flip this around. have exp[12] be single prerender as it is now, and
add an experiment for multiple prerenders.

[gavinp, 2012/07/23 18:35:21]

Done.

 
-  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;
+  base::FieldTrial::Probability exp2_probability = 150;
+  base::FieldTrial::Probability exp2_5min_ttl_probability = 67;
+  base::FieldTrial::Probability control2_probability = 150;
+  base::FieldTrial::Probability no_use2_probability = 67;
+  base::FieldTrial::Probability one_prerender2_probability = 66;
 
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
-    exp1_probability = 490;
+    exp1_probability = 0;
     exp1_5min_ttl_probability = 5;
     control1_probability = 5;
     no_use1_probability = 0;
-    exp2_probability = 490;
+    one_prerender1_probability = 490;
+    exp2_probability = 0;
     exp2_5min_ttl_probability = 5;
     control2_probability = 5;
     no_use2_probability = 0;
+    one_prerender2_probability = 490;
   }
   CHECK_EQ(divisor, exp1_probability + exp1_5min_ttl_probability +
-           control1_probability + no_use1_probability + exp2_probability +
+           control1_probability + no_use1_probability +
+           one_prerender1_probability + exp2_probability +
            exp2_5min_ttl_probability + control2_probability +
-           no_use2_probability);
+           no_use2_probability + one_prerender2_probability);
   int experiment_1_group = -1;
   scoped_refptr<base::FieldTrial> trial(
       base::FieldTrialList::FactoryGetFieldTrial(
           "Prerender", divisor, "ContentPrefetchPrerender1",
           2013, 6, 30, &experiment_1_group));
 
   const int experiment_15_min_TTL_group =
       trial->AppendGroup("ContentPrefetchPrerenderExp5minTTL1",
                          exp1_5min_ttl_probability);
   const int control_1_group =
       trial->AppendGroup("ContentPrefetchPrerenderControl1",
                          control1_probability);
   const int no_use_1_group =
       trial->AppendGroup("ContentPrefetchPrerenderNoUse1",
                          no_use1_probability);
+  const int one_prerender_1_group =
+      trial->AppendGroup("ContentPrefetchPrerenderOne",
+                         one_prerender1_probability);
   const int experiment_2_group =
       trial->AppendGroup("ContentPrefetchPrerender2",
                          exp2_probability);
   const int experiment_25_min_TTL_group =
       trial->AppendGroup("ContentPrefetchPrerenderExp5minTTL2",
                          exp2_5min_ttl_probability);
   const int control_2_group =
       trial->AppendGroup("ContentPrefetchPrerenderControl2",
                          control2_probability);
   const int no_use_2_group =
       trial->AppendGroup("ContentPrefetchPrerenderNoUse2",
                          no_use2_probability);
+  const int one_prerender_2_group =
+      trial->AppendGroup("ContentPrefetchPrerenderOne",
+                         one_prerender2_probability);
   const int trial_group = trial->group();
   if (trial_group == experiment_1_group ||
       trial_group == experiment_2_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
   } else if (trial_group == experiment_15_min_TTL_group ||
              trial_group == experiment_25_min_TTL_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_5MIN_TTL_GROUP);
   } else if (trial_group == control_1_group ||
              trial_group == control_2_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP);
   } else if (trial_group == no_use_1_group ||
              trial_group == no_use_2_group) {
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP);
+  } else if (trial_group == one_prerender_1_group ||
+             trial_group == one_prerender_2_group) {
+    PrerenderManager::SetMode(
+        PrerenderManager::PRERENDER_MODE_EXPERIMENT_ONE_PRERENDER_GROUP);
   } else {
     NOTREACHED();
   }
 }
 
 }  // end namespace
 
 void ConfigureOmniboxPrerender();
 void ConfigureSpeculativePrefetching();
 
@@ skipping 141 matching lines @@
     if (switch_value == switches::kSpeculativeResourcePrefetchingLearning)
       return true;
   }
 
   const int group = base::FieldTrialList::FindValue(
       kSpeculativePrefetchingLearningTrialName);
   return group == g_speculative_prefetching_learning_default_group_number;
 }
 
 }  // namespace prerender