Link MediaSessionTabHelper with native MediaSession [CL is going to be split]

content/browser/media/session/media_session_delegate_android.cc

Index: content/browser/media/session/media_session_delegate_android.cc
diff --git a/content/browser/media/session/media_session_delegate_android.cc b/content/browser/media/session/media_session_delegate_android.cc
new file mode 100644
index 0000000000000000000000000000000000000000..312cdff058e4bdf4a0acef22732baacf5a15f904
--- /dev/null
+++ b/content/browser/media/session/media_session_delegate_android.cc
@@ -0,0 +1,115 @@
+// 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 "base/android/scoped_java_ref.h"
+#include "content/browser/media/session/media_session.h"
+#include "content/common/android/media_metadata_android.h"
+#include "jni/MediaSessionDelegate_jni.h"
+
+using base::android::JavaParamRef;
+
+namespace content {
+
+// static
+bool MediaSessionDelegateAndroid::Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+// static
+void MediaSessionDelegateAndroid::CreateAndConnect(
+    MediaSession* session,
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& j_delegate) {
+  MediaSessionDelegateAndroid* delegate =
+      new MediaSessionDelegateAndroid(session, env, j_delegate);
+  session->PassObserverOwnership(
+      std::unique_ptr<MediaSessionDelegateAndroid>(delegate));
+  Java_MediaSessionDelegate_onMediaSessionConnected(

[whywhat, 2016/10/21 18:28:14]

I think "connect/disconnect" terms are misused and overloaded here. IIUC, this
is about notifying the Java and native parts about being created/destroyed so
they clean up the corresponding referenced.

These might go away with my comment above.

+      env, j_delegate, reinterpret_cast<intptr_t>(delegate));
+}
+
+MediaSessionDelegateAndroid::MediaSessionDelegateAndroid(
+    MediaSession* session,
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& j_delegate)
+    : MediaSessionObserver(session), j_delegate_(env, j_delegate) {}
+
+MediaSessionDelegateAndroid::~MediaSessionDelegateAndroid() {
+  MediaSessionDisconnected();
+}
+
+void MediaSessionDelegateAndroid::MediaSessionDisconnected() {
+  MediaSessionObserver::MediaSessionDisconnected();
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  ScopedJavaLocalRef<jobject> j_delegate_local = j_delegate_.get(env);
+  if (j_delegate_local.is_null()) return;
+
+  Java_MediaSessionDelegate_onMediaSessionDisconnected(env, j_delegate_local);
+}
+
+void MediaSessionDelegateAndroid::MediaSessionStateChanged(bool is_controllable,
+                                                           bool is_active) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  ScopedJavaLocalRef<jobject> j_delegate_local = j_delegate_.get(env);
+  if (j_delegate_local.is_null()) return;
+
+  Java_MediaSessionDelegate_mediaSessionStateChanged(
+      env, j_delegate_local, is_controllable, is_active);
+}
+
+void MediaSessionDelegateAndroid::MediaSessionMetadataChanged(
+    const base::Optional<MediaMetadata>& metadata) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  ScopedJavaLocalRef<jobject> j_delegate_local = j_delegate_.get(env);
+  if (j_delegate_local.is_null()) return;
+
+  base::android::ScopedJavaLocalRef<jobject> j_metadata;
+  if (metadata.has_value()) {
+    j_metadata =
+        MediaMetadataAndroid::CreateJavaObject(env, metadata.value());
+  }
+  Java_MediaSessionDelegate_mediaSessionMetadataChanged(
+      env, j_delegate_local.get(env), j_metadata);
+}
+
+void MediaSessionDelegateAndroid::ResumeMediaSession(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj) {
+  if (session())
+    session()->Resume(MediaSession::SuspendType::UI);
+}
+
+void MediaSessionDelegateAndroid::SuspendMediaSession(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj) {
+  if (session())
+    session()->Suspend(MediaSession::SuspendType::UI);
+}
+
+void MediaSessionDelegateAndroid::StopMediaSession(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj) {
+  if (session())
+    session()->Stop(MediaSession::SuspendType::UI);
+}
+
+void MediaSessionDelegateAndroid::DisconnectMediaSession(
+    JNIEnv* env,
+    const JavaParamRef<jobject>& obj) {
+  // Will destroy this and send `onMediaSessionDisconnected` to Java.
+  if (session())
+    session()->RemoveObserver(this);
+}
+
+}  // namespace content