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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/media/media_power_experiment_manager.h"
#include <memory>
#include <utility>
#include "base/feature_list.h"
#include "base/functional/callback_helpers.h"
#include "base/no_destructor.h"
#include "base/task/sequenced_task_runner.h"
#include "media/base/media_switches.h"
namespace content {
MediaPowerExperimentManager::MediaPowerExperimentManager()
: task_runner_(base::SequencedTaskRunner::GetCurrentDefault()) {}
MediaPowerExperimentManager::~MediaPowerExperimentManager() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}
void MediaPowerExperimentManager::PlayerStarted(const MediaPlayerId& player_id,
ExperimentCB cb) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
players_[player_id] = std::move(cb);
CheckExperimentState();
}
void MediaPowerExperimentManager::PlayerStopped(
const MediaPlayerId& player_id,
NotificationMode notification_mode) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// If we're supposed to skip notification, then clear the current player if
// it matches |player_id|, so that CheckExperimentState doesn't notify it.
if (notification_mode == NotificationMode::kSkip &&
current_experiment_player_ && *current_experiment_player_ == player_id) {
current_experiment_player_.reset();
current_experiment_cb_ = ExperimentCB();
// Note that there will be no incoming player; there's exactly one and we're
// removing it.
}
players_.erase(player_id);
CheckExperimentState();
}
void MediaPowerExperimentManager::CheckExperimentState() {
// See if an experiment should be running.
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
std::optional<MediaPlayerId> new_experiment_player;
if (players_.size() == 1)
new_experiment_player = players_.begin()->first;
// If there's a current experiment running, and it's not the same as the
// incoming one (if any), then stop it and clear the current player.
if (current_experiment_player_ &&
(!new_experiment_player ||
*current_experiment_player_ != *new_experiment_player)) {
task_runner_->PostTask(FROM_HERE,
base::BindOnce(current_experiment_cb_, false));
current_experiment_player_.reset();
current_experiment_cb_ = ExperimentCB();
}
// If there's an incoming player that's not currently running, then notify it
// and remember the current player.
if (!current_experiment_player_ && new_experiment_player) {
current_experiment_player_ = std::move(new_experiment_player);
// We cache the callback so that, when this player is stopped, we can
// notify it. Otherwise, it's removed from the map by the time we're here.
current_experiment_cb_ = players_.find(*current_experiment_player_)->second;
task_runner_->PostTask(FROM_HERE,
base::BindOnce(current_experiment_cb_, true));
}
}
// static
MediaPowerExperimentManager* MediaPowerExperimentManager::Instance() {
// Return nullptr unless an experiment is enabled that needs us.
if (base::FeatureList::IsEnabled(media::kMediaPowerExperiment)) {
static base::NoDestructor<MediaPowerExperimentManager> s_manager;
return s_manager.get();
}
return nullptr;
}
} // namespace content
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