Adding a field trial to enable speculative resource prefetching learning.

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"
 #include "chrome/browser/metrics/metrics_service.h"
 #include "chrome/browser/predictors/autocomplete_action_predictor.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/prerender/prerender_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
 
 namespace prerender {
 
 namespace {
 
 const char kOmniboxTrialName[] = "PrerenderFromOmnibox";
 int g_omnibox_trial_default_group_number = -1;
 
+const char kSpeculativePrefetchingLearningTrialName[] =
+    "SpeculativePrefetchingLearning";
+int g_speculative_prefetching_learning_default_group_number = -1;
+
 void SetupPrefetchFieldTrial() {
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
     return;
   }
 
   const base::FieldTrial::Probability divisor = 1000;
   const base::FieldTrial::Probability prefetch_probability = 500;
   scoped_refptr<base::FieldTrial> trial(
@@ skipping 79 matching lines @@
     PrerenderManager::SetMode(
         PrerenderManager::PRERENDER_MODE_EXPERIMENT_NO_USE_GROUP);
   } else {
     NOTREACHED();
   }
 }
 
 }  // end namespace
 
 void ConfigureOmniboxPrerender();
+void ConfigureSpeculativePrefetching();
 
 void ConfigurePrefetchAndPrerender(const CommandLine& command_line) {
   enum PrerenderOption {
     PRERENDER_OPTION_AUTO,
     PRERENDER_OPTION_DISABLED,
     PRERENDER_OPTION_ENABLED,
     PRERENDER_OPTION_PREFETCH_ONLY,
   };
 
   PrerenderOption prerender_option = PRERENDER_OPTION_AUTO;
@@ skipping 40 matching lines @@
       break;
     default:
       NOTREACHED();
   }
 
   UMA_HISTOGRAM_ENUMERATION("Prerender.Sessions",
                             PrerenderManager::GetMode(),
                             PrerenderManager::PRERENDER_MODE_MAX);
 
   ConfigureOmniboxPrerender();
+  ConfigureSpeculativePrefetching();
 }
 
 void ConfigureOmniboxPrerender() {
   // Field trial to see if we're enabled.
   const base::FieldTrial::Probability kDivisor = 100;
 
   base::FieldTrial::Probability kDisabledProbability = 10;
   chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
   if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
       channel == chrome::VersionInfo::CHANNEL_BETA) {
@@ skipping 28 matching lines @@
       return false;
 
     DCHECK(switch_value == switches::kPrerenderFromOmniboxSwitchValueAuto);
   }
 
   const int group = base::FieldTrialList::FindValue(kOmniboxTrialName);
   return group == base::FieldTrial::kNotFinalized ||
          group == g_omnibox_trial_default_group_number;
 }
 
+void ConfigureSpeculativePrefetching() {
+  // Field trial to see if we're enabled.
+  const base::FieldTrial::Probability kDivisor = 100;
+
+  base::FieldTrial::Probability kDisabledProbability = 99;
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (channel == chrome::VersionInfo::CHANNEL_STABLE ||
+      channel == chrome::VersionInfo::CHANNEL_BETA) {
+    kDisabledProbability = 100;
+  }
+  scoped_refptr<base::FieldTrial> speculative_prefetching_learning_trial(
+      base::FieldTrialList::FactoryGetFieldTrial(
+          kSpeculativePrefetchingLearningTrialName,
+          kDivisor,
+          "SpeculativePrefetchingLearningEnabled",
+          2012, 12, 30,
+          &g_speculative_prefetching_learning_default_group_number));
+  speculative_prefetching_learning_trial->AppendGroup(
+      "SpeculativePrefetchingDisabled",
+      kDisabledProbability);
+}
+
+bool IsSpeculativeResourcePrefetchingLearningEnabled(Profile* profile) {
+  if (!profile)
+    return false;
+
+  // Override any field trial groups if the user has set a command line flag.
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kSpeculativeResourcePrefetching)) {
+    const std::string switch_value =
+        CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kSpeculativeResourcePrefetching);
+
+    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