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

content/browser/media/session/media_session_delegate_android.h

+// 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 CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_
+#define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_
+
+#include <jni.h>
+
+#include "base/android/jni_weak_ref.h"
+#include "content/browser/media/session/media_session_observer.h"
+
+namespace content {
+
+// The class for listening to MediaSession messages and perform actions on the
+// MediaSession. This method is the native counterpart of Java

[whywhat, 2016/10/20 22:56:53]

s/method/class

[Zhiqiang Zhang (Slow), 2016/10/21 13:43:52]

Done.

+// MediaSessionDelegate. A native object its linked Java object must notify each

[whywhat, 2016/10/20 22:56:53]

s/A native object its linked/The native and the/

[Zhiqiang Zhang (Slow), 2016/10/21 13:43:52]

Done.

+// other when any of them is destroyed.
+class MediaSessionDelegateAndroid : public MediaSessionObserver {
+ public:
+  static bool Register(JNIEnv* env);
+
+  // Create a native MediaSessionDelegate object, start observe |media_session|,
+  // and link it to the |j_delegate| (its Java counterpart).
+  static void CreateAndConnect(
+      MediaSession* media_session,
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& j_delegate);
+
+  ~MediaSessionDelegateAndroid() override;
+
+  // MediaSessionObserver implementations
+  void MediaSessionDisconnected() override;
+  void MediaSessionStateChanged(bool is_controllable,
+                                bool is_suspended) override;
+  void MediaSessionMetadataChanged(
+      const base::Optional<MediaMetadata>& metadata) override;
+
+  // Resume the connected MediaSession.
+  void ResumeMediaSession(JNIEnv* env,
+                          const base::android::JavaParamRef<jobject>& obj);
+  // Suspend the connected MediaSession.
+  void SuspendMediaSession(JNIEnv* env,
+                           const base::android::JavaParamRef<jobject>& obj);
+  // Stop the connected MediaSession.
+  void StopMediaSession(JNIEnv* env,
+                        const base::android::JavaParamRef<jobject>& obj);
+  // Disconnect the connected MediaSession.
+  void DisconnectMediaSession(JNIEnv* env,
+                              const base::android::JavaParamRef<jobject>& obj);
+
+ private:
+  // Create a MediaSessionDelegateAndroid object and start observing
+  // |media_session|. Does not tell |j_delegate| to connect this object.
+  MediaSessionDelegateAndroid(
+      MediaSession* media_session,
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& j_delegate);
+
+  // The linked Java counterpart.
+  JavaObjectWeakGlobalRef j_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaSessionDelegateAndroid);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_DELEGATE_ANDROID_H_