Make MediaSession a runtime-enabled feature on Desktop.

content/browser/media/android/media_session.cc

Index: content/browser/media/android/media_session.cc
diff --git a/content/browser/media/android/media_session.cc b/content/browser/media/android/media_session.cc
deleted file mode 100644
index 17321058233891f393d93ea690ec112ea1af0eee..0000000000000000000000000000000000000000
--- a/content/browser/media/android/media_session.cc
+++ /dev/null
@@ -1,362 +0,0 @@
-// Copyright 2015 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 "content/browser/media/android/media_session.h"
-
-#include "base/android/context_utils.h"
-#include "base/android/jni_android.h"
-#include "content/browser/media/android/media_session_observer.h"
-#include "content/browser/web_contents/web_contents_impl.h"
-#include "content/public/browser/web_contents.h"
-#include "content/public/browser/web_contents_delegate.h"
-#include "jni/MediaSession_jni.h"
-#include "media/base/android/media_player_android.h"
-
-namespace content {
-
-using MediaSessionSuspendedSource =
-    MediaSessionUmaHelper::MediaSessionSuspendedSource;
-
-DEFINE_WEB_CONTENTS_USER_DATA_KEY(MediaSession);
-
-MediaSession::PlayerIdentifier::PlayerIdentifier(MediaSessionObserver* observer,
-                                                 int player_id)
-    : observer(observer),
-      player_id(player_id) {
-}
-
-bool MediaSession::PlayerIdentifier::operator==(
-    const PlayerIdentifier& other) const {
-  return this->observer == other.observer && this->player_id == other.player_id;
-}
-
-size_t MediaSession::PlayerIdentifier::Hash::operator()(
-    const PlayerIdentifier& player_identifier) const {
-  size_t hash = BASE_HASH_NAMESPACE::hash<MediaSessionObserver*>()(
-      player_identifier.observer);
-  hash += BASE_HASH_NAMESPACE::hash<int>()(player_identifier.player_id);
-  return hash;
-}
-
-// static
-bool content::MediaSession::RegisterMediaSession(JNIEnv* env) {
-  return RegisterNativesImpl(env);
-}
-
-// static
-MediaSession* MediaSession::Get(WebContents* web_contents) {
-  MediaSession* session = FromWebContents(web_contents);
-  if (!session) {
-    CreateForWebContents(web_contents);
-    session = FromWebContents(web_contents);
-    session->Initialize();
-  }
-  return session;
-}
-
-MediaSession::~MediaSession() {
-  DCHECK(players_.empty());
-  DCHECK(audio_focus_state_ == State::INACTIVE);
-}
-
-bool MediaSession::AddPlayer(MediaSessionObserver* observer,
-                             int player_id,
-                             Type type) {
-  observer->OnSetVolumeMultiplier(player_id, volume_multiplier_);
-
-  // If the audio focus is already granted and is of type Content, there is
-  // nothing to do. If it is granted of type Transient the requested type is
-  // also transient, there is also nothing to do. Otherwise, the session needs
-  // to request audio focus again.
-  if (audio_focus_state_ == State::ACTIVE &&
-      (audio_focus_type_ == Type::Content || audio_focus_type_ == type)) {
-    players_.insert(PlayerIdentifier(observer, player_id));
-    return true;
-  }
-
-  State old_audio_focus_state = audio_focus_state_;
-  State audio_focus_state = RequestSystemAudioFocus(type) ? State::ACTIVE
-                                                          : State::INACTIVE;
-  SetAudioFocusState(audio_focus_state);
-  audio_focus_type_ = type;
-
-  if (audio_focus_state_ != State::ACTIVE)
-    return false;
-
-  // The session should be reset if a player is starting while all players are
-  // suspended.
-  if (old_audio_focus_state != State::ACTIVE)
-    players_.clear();
-
-  players_.insert(PlayerIdentifier(observer, player_id));
-  UpdateWebContents();
-
-  return true;
-}
-
-void MediaSession::RemovePlayer(MediaSessionObserver* observer,
-                                int player_id) {
-  auto it = players_.find(PlayerIdentifier(observer, player_id));
-  if (it != players_.end())
-    players_.erase(it);
-
-  AbandonSystemAudioFocusIfNeeded();
-}
-
-void MediaSession::RemovePlayers(MediaSessionObserver* observer) {
-  for (auto it = players_.begin(); it != players_.end();) {
-    if (it->observer == observer)
-      players_.erase(it++);
-    else
-      ++it;
-  }
-
-  AbandonSystemAudioFocusIfNeeded();
-}
-
-void MediaSession::OnSuspend(JNIEnv* env,
-                             const JavaParamRef<jobject>& obj,
-                             jboolean temporary) {
-  // TODO(mlamouri): this check makes it so that if a MediaSession is paused and
-  // then loses audio focus, it will still stay in the Suspended state.
-  // See https://crbug.com/539998
-  if (audio_focus_state_ != State::ACTIVE)
-    return;
-
-  OnSuspendInternal(SuspendType::SYSTEM,
-                    temporary ? State::SUSPENDED : State::INACTIVE);
-
-}
-
-void MediaSession::OnResume(JNIEnv* env, const JavaParamRef<jobject>& obj) {
-  if (audio_focus_state_ != State::SUSPENDED)
-    return;
-
-  OnResumeInternal(SuspendType::SYSTEM);
-}
-
-void MediaSession::RecordSessionDuck(JNIEnv* env,
-                                     const JavaParamRef<jobject>& obj) {
-  uma_helper_.RecordSessionSuspended(
-      MediaSessionSuspendedSource::SystemTransientDuck);
-}
-
-void MediaSession::OnPlayerPaused(MediaSessionObserver* observer,
-                                  int player_id) {
-  // If a playback is completed, BrowserMediaPlayerManager will call
-  // OnPlayerPaused() after RemovePlayer(). This is a workaround.
-  // Also, this method may be called when a player that is not added
-  // to this session (e.g. a silent video) is paused. MediaSession
-  // should ignore the paused player for this case.
-  if (!players_.count(PlayerIdentifier(observer, player_id)))
-    return;
-
-  // If there is more than one observer, remove the paused one from the session.
-  if (players_.size() != 1) {
-    RemovePlayer(observer, player_id);
-    return;
-  }
-
-  // Otherwise, suspend the session.
-  DCHECK(!IsSuspended());
-  OnSuspendInternal(SuspendType::CONTENT, State::SUSPENDED);
-}
-void MediaSession::OnSetVolumeMultiplier(JNIEnv *env, jobject obj,
-                                         jdouble volume_multiplier) {
-  OnSetVolumeMultiplierInternal(volume_multiplier);
-}
-
-void MediaSession::Resume() {
-  DCHECK(IsSuspended());
-
-  // Request audio focus again in case we lost it because another app started
-  // playing while the playback was paused.
-  State audio_focus_state = RequestSystemAudioFocus(audio_focus_type_)
-                                ? State::ACTIVE
-                                : State::INACTIVE;
-  SetAudioFocusState(audio_focus_state);
-
-  if (audio_focus_state_ != State::ACTIVE)
-    return;
-
-  OnResumeInternal(SuspendType::UI);
-}
-
-void MediaSession::Suspend() {
-  DCHECK(!IsSuspended());
-
-  OnSuspendInternal(SuspendType::UI, State::SUSPENDED);
-}
-
-void MediaSession::Stop() {
-  DCHECK(audio_focus_state_ != State::INACTIVE);
-
-  if (audio_focus_state_ != State::SUSPENDED)
-    OnSuspendInternal(SuspendType::UI, State::SUSPENDED);
-
-  DCHECK(audio_focus_state_ == State::SUSPENDED);
-  players_.clear();
-  AbandonSystemAudioFocusIfNeeded();
-}
-
-bool MediaSession::IsSuspended() const {
-  // TODO(mlamouri): should be == State::SUSPENDED.
-  return audio_focus_state_ != State::ACTIVE;
-}
-
-bool MediaSession::IsControllable() const {
-  // Only content type media session can be controllable unless it is inactive.
-  return audio_focus_state_ != State::INACTIVE &&
-         audio_focus_type_ == Type::Content;
-}
-
-void MediaSession::ResetJavaRefForTest() {
-  j_media_session_.Reset();
-}
-
-bool MediaSession::IsActiveForTest() const {
-  return audio_focus_state_ == State::ACTIVE;
-}
-
-MediaSession::Type MediaSession::audio_focus_type_for_test() const {
-  return audio_focus_type_;
-}
-
-MediaSessionUmaHelper* MediaSession::uma_helper_for_test() {
-  return &uma_helper_;
-}
-
-void MediaSession::RemoveAllPlayersForTest() {
-  players_.clear();
-  AbandonSystemAudioFocusIfNeeded();
-}
-
-void MediaSession::OnSuspendInternal(SuspendType type, State new_state) {
-  DCHECK(new_state == State::SUSPENDED || new_state == State::INACTIVE);
-  // UI suspend cannot use State::INACTIVE.
-  DCHECK(type == SuspendType::SYSTEM || new_state == State::SUSPENDED);
-
-  switch (type) {
-    case SuspendType::UI:
-      uma_helper_.RecordSessionSuspended(MediaSessionSuspendedSource::UI);
-      break;
-    case SuspendType::SYSTEM:
-      switch (new_state) {
-        case State::SUSPENDED:
-          uma_helper_.RecordSessionSuspended(
-              MediaSessionSuspendedSource::SystemTransient);
-          break;
-        case State::INACTIVE:
-          uma_helper_.RecordSessionSuspended(
-              MediaSessionSuspendedSource::SystemPermanent);
-          break;
-        case State::ACTIVE:
-          NOTREACHED();
-          break;
-      }
-      break;
-    case SuspendType::CONTENT:
-      uma_helper_.RecordSessionSuspended(MediaSessionSuspendedSource::CONTENT);
-      break;
-  }
-
-  SetAudioFocusState(new_state);
-  suspend_type_ = type;
-
-  if (type != SuspendType::CONTENT) {
-    // SuspendType::CONTENT happens when the suspend action came from
-    // the page in which case the player is already paused.
-    // Otherwise, the players need to be paused.
-    for (const auto& it : players_)
-      it.observer->OnSuspend(it.player_id);
-  }
-
-  UpdateWebContents();
-}
-
-void MediaSession::OnResumeInternal(SuspendType type) {
-  if (type == SuspendType::SYSTEM && suspend_type_ != type)
-    return;
-
-  SetAudioFocusState(State::ACTIVE);
-
-  for (const auto& it : players_)
-    it.observer->OnResume(it.player_id);
-
-  UpdateWebContents();
-}
-
-void MediaSession::OnSetVolumeMultiplierInternal(double volume_multiplier) {
-  volume_multiplier_ = volume_multiplier;
-  for (const auto& it : players_)
-    it.observer->OnSetVolumeMultiplier(it.player_id, volume_multiplier_);
-}
-
-MediaSession::MediaSession(WebContents* web_contents)
-    : WebContentsObserver(web_contents),
-      audio_focus_state_(State::INACTIVE),
-      audio_focus_type_(Type::Transient),
-      volume_multiplier_(media::MediaPlayerAndroid::kDefaultVolumeMultiplier) {
-}
-
-void MediaSession::Initialize() {
-  JNIEnv* env = base::android::AttachCurrentThread();
-  DCHECK(env);
-  j_media_session_.Reset(Java_MediaSession_createMediaSession(
-      env,
-      base::android::GetApplicationContext(),
-      reinterpret_cast<intptr_t>(this)));
-}
-
-bool MediaSession::RequestSystemAudioFocus(Type type) {
-  // During tests, j_media_session_ might be null.
-  if (j_media_session_.is_null())
-    return true;
-
-  JNIEnv* env = base::android::AttachCurrentThread();
-  DCHECK(env);
-  bool result = Java_MediaSession_requestAudioFocus(env, j_media_session_.obj(),
-                                                    type == Type::Transient);
-  uma_helper_.RecordRequestAudioFocusResult(result);
-  return result;
-}
-
-void MediaSession::AbandonSystemAudioFocusIfNeeded() {
-  if (audio_focus_state_ == State::INACTIVE || !players_.empty())
-    return;
-
-  // During tests, j_media_session_ might be null.
-  if (!j_media_session_.is_null()) {
-    JNIEnv* env = base::android::AttachCurrentThread();
-    DCHECK(env);
-    Java_MediaSession_abandonAudioFocus(env, j_media_session_.obj());
-  }
-
-  SetAudioFocusState(State::INACTIVE);
-  UpdateWebContents();
-}
-
-void MediaSession::UpdateWebContents() {
-  static_cast<WebContentsImpl*>(web_contents())->OnMediaSessionStateChanged();
-}
-
-void MediaSession::SetAudioFocusState(State audio_focus_state) {
-  if (audio_focus_state == audio_focus_state_)
-    return;
-
-  audio_focus_state_ = audio_focus_state;
-  switch (audio_focus_state_) {
-    case State::ACTIVE:
-      uma_helper_.OnSessionActive();
-      break;
-    case State::SUSPENDED:
-      uma_helper_.OnSessionSuspended();
-      break;
-    case State::INACTIVE:
-      uma_helper_.OnSessionInactive();
-      break;
-  }
-}
-
-}  // namespace content