Hook up RendererMediaSessionManager with browser side

content/renderer/media/android/webmediasession_android.h

Index: content/renderer/media/android/webmediasession_android.h
diff --git a/content/renderer/media/android/webmediasession_android.h b/content/renderer/media/android/webmediasession_android.h
index b27d51a5cee2be13e7b7d54c40ca6e7ea49a9cd1..d7f0b080615b993eca2fdc5f47a47fe3f83a7e09 100644
--- a/content/renderer/media/android/webmediasession_android.h
+++ b/content/renderer/media/android/webmediasession_android.h
@@ -5,6 +5,8 @@
 #ifndef CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIASESSION_ANDROID_H_
 #define CONTENT_RENDERER_MEDIA_ANDROID_WEBMEDIASESSION_ANDROID_H_
 
+#include <map>
+
 #include "base/macros.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/modules/mediasession/WebMediaSession.h"
@@ -21,9 +23,23 @@ class CONTENT_EXPORT WebMediaSessionAndroid : public blink::WebMediaSession {
   void activate(blink::WebMediaSessionActivateCallback*) override;
   void deactivate(blink::WebMediaSessionDeactivateCallback*) override;
 
+  void OnDidActivate(int activation_id, bool success);
+  void OnDidDeactivate(int deactivation_id);
+
+  int session_id() const { return session_id_; }
+
  private:
   RendererMediaSessionManager* const session_manager_;
   int session_id_;
+  int next_action_id_;
+
+  struct SessionAction {
+    SessionAction() : activate(nullptr), deactivate(nullptr) {}
+    blink::WebMediaSessionActivateCallback* activate;
+    blink::WebMediaSessionDeactivateCallback* deactivate;
+  };
+
+  std::map<int, SessionAction> actions_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaSessionAndroid);
 };