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// Copyright (c) 2011 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 "content/browser/renderer_host/resource_dispatcher_host.h"
#include "chrome/browser/prerender/prerender_manager.h"
#include "chrome/common/chrome_switches.h"
namespace prerender {
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;
if (command_line.HasSwitch(switches::kPrerender)) {
const std::string switch_value =
command_line.GetSwitchValueASCII(switches::kPrerender);
if (switch_value == switches::kPrerenderSwitchValueAuto) {
#if defined(OS_CHROMEOS)
// Prerender is temporarily disabled on CrOS.
// http://crosbug.com/12483
prerender_option = PRERENDER_OPTION_DISABLED;
#else
prerender_option = PRERENDER_OPTION_AUTO;
#endif
} else if (switch_value == switches::kPrerenderSwitchValueDisabled) {
prerender_option = PRERENDER_OPTION_DISABLED;
} else if (switch_value.empty() ||
switch_value == switches::kPrerenderSwitchValueEnabled) {
// The empty string means the option was provided with no value, and that
// means enable.
prerender_option = PRERENDER_OPTION_ENABLED;
} else if (switch_value == switches::kPrerenderSwitchValuePrefetchOnly) {
prerender_option = PRERENDER_OPTION_PREFETCH_ONLY;
} else {
prerender_option = PRERENDER_OPTION_DISABLED;
LOG(ERROR) << "Invalid --prerender option received on command line: "
<< switch_value;
LOG(ERROR) << "Disabling prerendering!";
}
}
switch (prerender_option) {
case PRERENDER_OPTION_AUTO: {
const base::FieldTrial::Probability kPrefetchDivisor = 1000;
const base::FieldTrial::Probability kYesPrefetchProbability = 0;
const base::FieldTrial::Probability kPrerenderExp1Probability = 400;
const base::FieldTrial::Probability kPrerenderControl1Probability = 100;
const base::FieldTrial::Probability kPrerenderExp2Probability = 400;
const base::FieldTrial::Probability kPrerenderControl2Probability = 100;
scoped_refptr<base::FieldTrial> trial(
new base::FieldTrial("Prefetch", kPrefetchDivisor,
"ContentPrefetchDisabled", 2011, 6, 30));
const int kNoPrefetchGroup = trial->kDefaultGroupNumber;
const int kYesPrefetchGroup =
trial->AppendGroup("ContentPrefetchEnabled", kYesPrefetchProbability);
const int kPrerenderExperiment1Group =
trial->AppendGroup("ContentPrefetchPrerender1",
kPrerenderExp1Probability);
const int kPrerenderControl1Group =
trial->AppendGroup("ContentPrefetchPrerenderControl1",
kPrerenderControl1Probability);
const int kPrerenderExperiment2Group =
trial->AppendGroup("ContentPrefetchPrerender2",
kPrerenderExp2Probability);
const int kPrerenderControl2Group =
trial->AppendGroup("ContentPrefetchPrerenderControl2",
kPrerenderControl2Probability);
const int trial_group = trial->group();
if (trial_group == kYesPrefetchGroup) {
ResourceDispatcherHost::set_is_prefetch_enabled(true);
PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
} else if (trial_group == kNoPrefetchGroup) {
ResourceDispatcherHost::set_is_prefetch_enabled(false);
PrerenderManager::SetMode(
PrerenderManager::PRERENDER_MODE_DISABLED);
} else if (trial_group == kPrerenderExperiment1Group ||
trial_group == kPrerenderExperiment2Group) {
ResourceDispatcherHost::set_is_prefetch_enabled(true);
PrerenderManager::SetMode(
PrerenderManager::PRERENDER_MODE_EXPERIMENT_PRERENDER_GROUP);
} else if (trial_group == kPrerenderControl1Group ||
trial_group == kPrerenderControl2Group) {
ResourceDispatcherHost::set_is_prefetch_enabled(true);
PrerenderManager::SetMode(
PrerenderManager::PRERENDER_MODE_EXPERIMENT_CONTROL_GROUP);
} else {
NOTREACHED();
}
break;
}
case PRERENDER_OPTION_DISABLED:
ResourceDispatcherHost::set_is_prefetch_enabled(false);
PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
break;
case PRERENDER_OPTION_ENABLED:
ResourceDispatcherHost::set_is_prefetch_enabled(true);
PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_ENABLED);
break;
case PRERENDER_OPTION_PREFETCH_ONLY:
ResourceDispatcherHost::set_is_prefetch_enabled(true);
PrerenderManager::SetMode(PrerenderManager::PRERENDER_MODE_DISABLED);
break;
default:
NOTREACHED();
}
UMA_HISTOGRAM_ENUMERATION("Prerender.Sessions",
PrerenderManager::GetMode(),
PrerenderManager::PRERENDER_MODE_MAX);
}
} // namespace prerender
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