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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.
#ifndef COMPONENTS_VARIATIONS_FIELD_TRIAL_SYNCER_H_
#define COMPONENTS_VARIATIONS_FIELD_TRIAL_SYNCER_H_
#include <string>
#include "base/macros.h"
#include "base/metrics/field_trial.h"
namespace base {
class CommandLine;
}
namespace variations {
// ChildProcessFieldTrialSyncer is a utility class that's responsible for
// syncing the "activated" state of field trials between browser and child
// processes. Specifically, when a field trial is activated in the browser, it
// also activates it in the child process and when a field trial is activated
// in the child process, it notifies the browser process to activate it.
class ChildProcessFieldTrialSyncer {
public:
// ChildProcessFieldTrialSyncer constructor taking an externally owned
// |observer| param that's responsible for sending IPCs to the browser process
// when a trial is activated. The |observer| must outlive this object.
explicit ChildProcessFieldTrialSyncer(
base::FieldTrialList::Observer* observer);
~ChildProcessFieldTrialSyncer();
// Initializes field trial state change observation and notifies the browser
// of any field trials that might have already been activated. Takes the
// switch name for single process mode as a parameter, since that's not
// visible to the component.
void InitFieldTrialObserving(const base::CommandLine& command_line,
const char* single_process_switch_name);
// Handler for messages from the browser process notifying the child process
// that a field trial was activated.
void OnSetFieldTrialGroup(const std::string& trial_name,
const std::string& group_name);
private:
base::FieldTrialList::Observer* const observer_;
DISALLOW_COPY_AND_ASSIGN(ChildProcessFieldTrialSyncer);
};
} // namespace variations
#endif // COMPONENTS_VARIATIONS_FIELD_TRIAL_SYNCER_H_
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