Add render-side manager for MediaSession

content/renderer/media/android/renderer_media_session_manager.cc

+// 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.
+
+#include "content/renderer/media/android/renderer_media_session_manager.h"
+
+#include "base/logging.h"
+#include "content/renderer/media/android/webmediasession_android.h"
+
+namespace content {
+
+const int kDefaultMediaSession = 0;  // ID of the default media session

[philipj_slow, 2015/11/16 14:06:21]

Perhaps append ID to this name?

[davve, 2015/11/16 14:34:26]

Done.

+
+RendererMediaSessionManager::RendererMediaSessionManager(
+    RenderFrame* render_frame)
+    : RenderFrameObserver(render_frame),
+      next_session_id_(kDefaultMediaSession + 1) {}
+
+RendererMediaSessionManager::~RendererMediaSessionManager() {
+  DCHECK(sessions_.empty())
+      << "RendererMediaSessionManager is owned by RenderFrameImpl and is "
+         "destroyed only after all media sessions are destroyed.";
+}
+
+int RendererMediaSessionManager::RegisterMediaSession(
+    WebMediaSessionAndroid* session) {
+  sessions_[next_session_id_] = session;
+  return next_session_id_++;

[philipj_slow, 2015/11/16 14:06:21]

Maybe CHECK that this doesn't overflow so that it just crashes if it ever does?
Would like to hear what the other reviewers say about that.

[davve, 2015/11/16 14:34:26]

Adding a check sounds good, but I'm also curious what other reviewers think.

+}
+
+void RendererMediaSessionManager::UnregisterMediaSession(int session_id) {
+  sessions_.erase(session_id);
+}
+
+}  // namespace content