Hook up RendererMediaSessionManager with browser side

content/common/media/media_session_messages_android.h

Index: content/common/media/media_session_messages_android.h
diff --git a/content/common/media/media_session_messages_android.h b/content/common/media/media_session_messages_android.h
new file mode 100644
index 0000000000000000000000000000000000000000..304f88c9527616cfa53c2b6e0108eca270677e94
--- /dev/null
+++ b/content/common/media/media_session_messages_android.h
@@ -0,0 +1,36 @@
+// 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.
+
+// IPC messages for the Media Session API.
+// Multiply-included message file, hence no include guard.
+
+#include "base/basictypes.h"
+#include "content/common/android/gin_java_bridge_errors.h"
+#include "content/common/content_export.h"
+#include "ipc/ipc_message_macros.h"
+
+#undef IPC_MESSAGE_EXPORT
+#define IPC_MESSAGE_EXPORT CONTENT_EXPORT
+#define IPC_MESSAGE_START MediaSessionMsgStart
+
+// Messages for notifying the render process of media session status -------
+
+IPC_MESSAGE_ROUTED3(MediaSessionMsg_DidActivate,
+                    int /* session_id */,
+                    int /* request_id */,
+                    bool /* success */)

[mlamouri (slow - plz ping), 2015/12/07 18:14:52]

Just note that we could make |request_id| map to the right |session_id|. I think
what you have here is fine given that we don't reuse |session_id| in the same
process.

[davve, 2015/12/08 10:21:23]

Acknowledged.

+
+IPC_MESSAGE_ROUTED2(MediaSessionMsg_DidDeactivate,
+                    int /* session_id */,
+                    int /* request_id */)
+
+// Messages for controlling the media session in browser process ----------
+
+IPC_MESSAGE_ROUTED2(MediaSessionHostMsg_Activate,
+                    int /* session_id */,
+                    int /* request_id */)
+
+IPC_MESSAGE_ROUTED2(MediaSessionHostMsg_Deactivate,
+                    int /* session_id */,
+                    int /* request_id */)