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

content/browser/web_contents/web_contents_android.cc

Index: content/browser/web_contents/web_contents_android.cc
diff --git a/content/browser/web_contents/web_contents_android.cc b/content/browser/web_contents/web_contents_android.cc
index 054aaffdaf89e1223c51cbe97b0bc4d8f44091b4..49f504e8f2dae1f8b384d5e895f78b9de75d6197 100644
--- a/content/browser/web_contents/web_contents_android.cc
+++ b/content/browser/web_contents/web_contents_android.cc
@@ -11,6 +11,7 @@
 #include "base/android/jni_string.h"
 #include "base/command_line.h"
 #include "base/containers/hash_tables.h"
+#include "base/memory/ptr_util.h"
 #include "base/json/json_writer.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
@@ -21,6 +22,8 @@
 #include "content/browser/frame_host/interstitial_page_impl.h"
 #include "content/browser/media/android/browser_media_player_manager.h"
 #include "content/browser/media/android/media_web_contents_observer_android.h"
+#include "content/browser/media/session/media_session.h"
+#include "content/browser/media/session/media_session_delegate_android.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/devtools_messages.h"
@@ -613,19 +616,11 @@ void WebContentsAndroid::RequestAccessibilitySnapshot(
       snapshot_callback);
 }
 
-void WebContentsAndroid::ResumeMediaSession(JNIEnv* env,
-                                            const JavaParamRef<jobject>& obj) {
-  web_contents_->ResumeMediaSession();
-}
-
-void WebContentsAndroid::SuspendMediaSession(JNIEnv* env,
-                                             const JavaParamRef<jobject>& obj) {
-  web_contents_->SuspendMediaSession();
-}
-
-void WebContentsAndroid::StopMediaSession(JNIEnv* env,
-                                          const JavaParamRef<jobject>& obj) {
-  web_contents_->StopMediaSession();
+void WebContentsAndroid::AddMediaSessionDelegate(JNIEnv* env,
+                                                 const JavaParamRef<jobject>& obj,
+                                                 const JavaParamRef<jobject>& j_delegate) {
+  MediaSessionDelegateAndroid::CreateAndRegister(

[whywhat, 2016/10/20 15:38:33]

perhaps the delegates could be owned by WebContents?

[Zhiqiang Zhang (Slow), 2016/10/20 16:22:32]

I prefer not to pollute WebContents. Actually MediaSession has the same lifetime
as WebContents.

[whywhat, 2016/10/20 18:21:16]

Can we just own MSO in MediaSession and avoid using the observer pattern at all
then? You just register MSO with MS, it owns it and calls its methods. We don't
have cases of MSOs that are not owned by MS or that are owned but don't want to
observe the events right? If we do, I'll have to think more, perhaps :)

+      env, MediaSession::Get(web_contents()), j_delegate);
 }
 
 ScopedJavaLocalRef<jstring> WebContentsAndroid::GetEncoding(