Make MediaSession a runtime-enabled feature on Desktop.

content/browser/media/session/media_session_delegate_android.cc

+// 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 "content/browser/media/session/media_session_delegate_android.h"
+
+#include "base/android/context_utils.h"
+#include "base/android/jni_android.h"
+#include "jni/MediaSessionDelegate_jni.h"
+
+namespace content {
+
+// static
+bool MediaSessionDelegateAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+MediaSessionDelegateAndroid::MediaSessionDelegateAndroid(
+    MediaSession* media_session)
+    : media_session_(media_session) {
+}
+
+MediaSessionDelegateAndroid::~MediaSessionDelegateAndroid() = default;
+
+void MediaSessionDelegateAndroid::Initialize() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+  j_media_session_delegate_.Reset(Java_MediaSessionDelegate_create(
+      env,
+      base::android::GetApplicationContext(),
+      reinterpret_cast<intptr_t>(this)));
+}
+
+bool MediaSessionDelegateAndroid::RequestAudioFocus(MediaSession::Type type) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+  return Java_MediaSessionDelegate_requestAudioFocus(
+      env, j_media_session_delegate_.obj(),
+      type == MediaSession::Type::Transient);
+}
+
+void MediaSessionDelegateAndroid::AbandonAudioFocus() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+  Java_MediaSessionDelegate_abandonAudioFocus(
+      env, j_media_session_delegate_.obj());
+}
+
+void MediaSessionDelegateAndroid::OnSuspend(
+    JNIEnv*, const JavaParamRef<jobject>&, 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 (!media_session_->IsActive())
+    return;
+
+  if (temporary) {
+    media_session_->Suspend(MediaSession::SuspendType::SYSTEM);
+  } else {
+    media_session_->Stop(MediaSession::SuspendType::SYSTEM);
+  }
+}
+
+void MediaSessionDelegateAndroid::OnResume(
+    JNIEnv*, const JavaParamRef<jobject>&) {
+  if (!media_session_->IsReallySuspended())
+    return;
+
+  media_session_->Resume(MediaSession::SuspendType::SYSTEM);
+}
+
+void MediaSessionDelegateAndroid::OnSetVolumeMultiplier(
+    JNIEnv*, jobject, jdouble volume_multiplier) {
+  media_session_->SetVolumeMultiplier(volume_multiplier);
+}
+
+void MediaSessionDelegateAndroid::RecordSessionDuck(
+    JNIEnv*, const JavaParamRef<jobject>&) {
+  media_session_->RecordSessionDuck();
+}
+
+// static
+scoped_ptr<MediaSessionDelegate> MediaSessionDelegate::Create(
+    MediaSession* media_session) {
+  MediaSessionDelegateAndroid* delegate =
+      new MediaSessionDelegateAndroid(media_session);
+  delegate->Initialize();
+  return scoped_ptr<MediaSessionDelegate>(delegate);
+}
+
+}  // namespace content