[cast_channel] Make CastSocketService a global leaky singleton

components/cast_channel/cast_socket_service.h

Index: components/cast_channel/cast_socket_service.h
diff --git a/components/cast_channel/cast_socket_service.h b/components/cast_channel/cast_socket_service.h
index bb465e920dc1f654035c25d6705c8136ceb391f3..d7dc8c29c98be27f3475eb72ef6810412fbb38b2 100644
--- a/components/cast_channel/cast_socket_service.h
+++ b/components/cast_channel/cast_socket_service.h
@@ -9,9 +9,9 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/singleton.h"
 #include "base/threading/thread_checker.h"
 #include "components/cast_channel/cast_socket.h"
-#include "components/keyed_service/core/refcounted_keyed_service.h"
 #include "content/public/browser/browser_thread.h"
 
 namespace cast_channel {
@@ -20,9 +20,9 @@ namespace cast_channel {
 // to underlying storage.
 // Instance of this class is created on the UI thread and destroyed on the IO
 // thread. All public API must be called from the IO thread.
-class CastSocketService : public RefcountedKeyedService {
+class CastSocketService {
  public:
-  CastSocketService();
+  static CastSocketService* GetInstance();
 
   // Returns a pointer to the Logger member variable.
   scoped_refptr<cast_channel::Logger> GetLogger();
@@ -77,24 +77,20 @@ class CastSocketService : public RefcountedKeyedService {
                          const CastSocket::OnOpenCallback& open_cb,
                          CastSocket::Observer* observer);
 
-  // Returns an observer corresponding to |id|.
-  CastSocket::Observer* GetObserver(const std::string& id);
-
-  // Adds |observer| to |socket_observer_map_| keyed by |id|. Return raw pointer
-  // of the newly added observer.
-  CastSocket::Observer* AddObserver(
-      const std::string& id,
-      std::unique_ptr<CastSocket::Observer> observer);
+  // Remove |observer| from each socket in |sockets_|
+  void RemoveObserver(CastSocket::Observer* observer);
 
   // Allow test to inject a mock cast socket.
   void SetSocketForTest(std::unique_ptr<CastSocket> socket_for_test);
 
- protected:
-  ~CastSocketService() override;
-
  private:
-  // RefcountedKeyedService implementation.
-  void ShutdownOnUIThread() override;
+  friend class CastSocketServiceTest;
+  friend class MockCastSocketService;
+  friend struct base::DefaultSingletonTraits<CastSocketService>;
+  friend struct std::default_delete<CastSocketService>;
+
+  CastSocketService();
+  virtual ~CastSocketService();
 
   // Used to generate CastSocket id.
   static int last_channel_id_;
@@ -102,13 +98,7 @@ class CastSocketService : public RefcountedKeyedService {
   // The collection of CastSocket keyed by channel_id.
   std::map<int, std::unique_ptr<CastSocket>> sockets_;
 
-  // Map of CastSocket::Observer keyed by observer id. For extension side
-  // observers, id is extension_id; For browser side observers, id is a hard
-  // coded string.
-  std::map<std::string, std::unique_ptr<CastSocket::Observer>>
-      socket_observer_map_;
-
-  scoped_refptr<cast_channel::Logger> logger_;
+  scoped_refptr<Logger> logger_;
 
   std::unique_ptr<CastSocket> socket_for_test_;