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// Copyright 2016 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 "components/variations/child_process_field_trial_syncer.h"
#include <set>
#include <utility>
#include "base/base_switches.h"
#include "base/command_line.h"
#include "base/containers/contains.h"
#include "components/variations/variations_crash_keys.h"
namespace variations {
namespace {
ChildProcessFieldTrialSyncer* g_instance = nullptr;
} // namespace
// static
ChildProcessFieldTrialSyncer* ChildProcessFieldTrialSyncer::CreateInstance(
FieldTrialActivatedCallback activated_callback) {
DCHECK(!g_instance);
g_instance = new ChildProcessFieldTrialSyncer(std::move(activated_callback));
g_instance->Init();
return g_instance;
}
// static
void ChildProcessFieldTrialSyncer::DeleteInstanceForTesting() {
DCHECK(g_instance);
delete g_instance;
g_instance = nullptr;
// Revert the effect of calling variations::InitCrashKeys() in Init().
ClearCrashKeysInstanceForTesting(); // IN-TEST
}
ChildProcessFieldTrialSyncer::ChildProcessFieldTrialSyncer(
FieldTrialActivatedCallback activated_callback)
: activated_callback_(std::move(activated_callback)) {}
ChildProcessFieldTrialSyncer::~ChildProcessFieldTrialSyncer() = default;
void ChildProcessFieldTrialSyncer::Init() {
// Set up initial set of crash dump data for field trials in this process.
variations::InitCrashKeys();
// Listen for field trial activations to report them to the browser.
base::FieldTrialList::AddObserver(this);
// Some field trials may have been activated before this point. Notify the
// browser of these activations now. To detect these, take the set difference
// of currently active trials with the initially active trials.
base::FieldTrial::ActiveGroups initially_active_trials;
base::FieldTrialList::GetInitiallyActiveFieldTrials(
*base::CommandLine::ForCurrentProcess(), &initially_active_trials);
std::set<std::string> initially_active_trials_set;
for (const auto& entry : initially_active_trials) {
initially_active_trials_set.insert(std::move(entry.trial_name));
}
base::FieldTrial::ActiveGroups current_active_trials;
base::FieldTrialList::GetActiveFieldTrialGroups(¤t_active_trials);
for (const auto& trial : current_active_trials) {
if (!base::Contains(initially_active_trials_set, trial.trial_name))
activated_callback_.Run(trial.trial_name);
}
}
void ChildProcessFieldTrialSyncer::SetFieldTrialGroupFromBrowser(
const std::string& trial_name,
const std::string& group_name) {
DCHECK(!in_set_field_trial_group_from_browser_.Get());
in_set_field_trial_group_from_browser_.Set(true);
base::FieldTrial* trial =
base::FieldTrialList::CreateFieldTrial(trial_name, group_name);
// Ensure the trial is marked as "used" by calling group() on it if it is
// marked as activated.
trial->group();
in_set_field_trial_group_from_browser_.Set(false);
}
void ChildProcessFieldTrialSyncer::OnFieldTrialGroupFinalized(
const std::string& trial_name,
const std::string& group_name) {
// It is not necessary to notify the browser if this is invoked from
// SetFieldTrialGroupFromBrowser().
if (in_set_field_trial_group_from_browser_.Get())
return;
activated_callback_.Run(trial_name);
}
} // namespace variations
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