Revert of [Presentation API] Implement ondefaultsessionstart in PSImpl.

content/public/browser/presentation_service_delegate.h

Index: content/public/browser/presentation_service_delegate.h
diff --git a/content/public/browser/presentation_service_delegate.h b/content/public/browser/presentation_service_delegate.h
index fd82045e669888a756a16a85336eed7f723fb7fd..817cd282a8f246eac8ac6a2e7bda0ccba940f5f7 100644
--- a/content/public/browser/presentation_service_delegate.h
+++ b/content/public/browser/presentation_service_delegate.h
@@ -23,13 +23,6 @@
     // Called when the PresentationServiceDelegate is being destroyed.
     virtual void OnDelegateDestroyed() = 0;
 
-    // Called when the default presentation has been started outside of a
-    // Presentation API context (e.g., browser action). This will not be called
-    // if the session was created as a result of Presentation API's
-    // StartSession()/JoinSession().
-    virtual void OnDefaultPresentationStarted(
-        const PresentationSessionInfo& session) = 0;
-
    protected:
     virtual ~Observer() {}
   };
@@ -41,19 +34,12 @@
 
   virtual ~PresentationServiceDelegate() {}
 
-  // Registers an observer associated with frame with |render_process_id|
-  // and |render_frame_id| with this class to listen for updates.
+  // Registers an observer with this class to listen for updates to this class.
   // This class does not own the observer.
-  // It is an error to add an observer if there is already an observer for that
-  // frame.
-  virtual void AddObserver(int render_process_id,
-                           int render_frame_id,
-                           Observer* observer) = 0;
-
-  // Unregisters the observer associated with the frame with |render_process_id|
-  // and |render_frame_id|.
-  // The observer will no longer receive updates.
-  virtual void RemoveObserver(int render_process_id, int render_frame_id) = 0;
+  // It is an error to add an observer if it has already been added before.
+  virtual void AddObserver(Observer* observer) = 0;
+  // Unregisters an observer with this class.
+  virtual void RemoveObserver(Observer* observer) = 0;
 
   // Registers |listener| to continuously listen for
   // availability updates for a presentation URL, originated from the frame