[Presentation API / Media Router] Clean up default pres URL logic.

content/public/browser/presentation_service_delegate.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_PRESENTATION_SERVICE_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_PRESENTATION_SERVICE_DELEGATE_H_
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/presentation_session.h"
 #include "content/public/browser/presentation_session_message.h"
 
 namespace content {
 
 class PresentationScreenAvailabilityListener;
 
+using PresentationSessionStartedCallback =
+    base::Callback<void(const PresentationSessionInfo&)>;
+using PresentationSessionErrorCallback =
+    base::Callback<void(const PresentationError&)>;
 using SessionStateChangedCallback =
     base::Callback<void(const PresentationSessionInfo&,
                         PresentationSessionState)>;
 
 // Param #0: a vector of messages that are received.
 // Param #1: tells the callback handler that it may reuse strings or buffers
 //           in the messages contained within param #0.
 using PresentationSessionMessageCallback = base::Callback<
     void(const ScopedVector<content::PresentationSessionMessage>&, bool)>;
 
 // An interface implemented by embedders to handle presentation API calls
 // forwarded from PresentationServiceImpl.
 class CONTENT_EXPORT PresentationServiceDelegate {
  public:
   // Observer interface to listen for changes to PresentationServiceDelegate.
   class CONTENT_EXPORT Observer {
    public:
     // 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() {}
   };
 
-  using PresentationSessionSuccessCallback =
-      base::Callback<void(const PresentationSessionInfo&)>;
-  using PresentationSessionErrorCallback =
-      base::Callback<void(const PresentationError&)>;
   using SendMessageCallback = base::Callback<void(bool)>;
 
   virtual ~PresentationServiceDelegate() {}
 
   // Registers an observer associated with frame with |render_process_id|
   // and |render_frame_id| with this class to listen for updates.
   // 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,
@@ skipping 27 matching lines @@
 
   // Resets the presentation state for the frame given by |render_process_id|
   // and |render_frame_id|.
   // This unregisters all listeners associated with the given frame, and clears
   // the default presentation URL and ID set for the frame.
   virtual void Reset(
       int render_process_id,
       int render_frame_id) = 0;
 
   // Sets the default presentation URL for frame given by |render_process_id|
-  // and |render_frame_id|.
+  // and |render_frame_id|. When the default presentation is started on this
+  // frame, |callback| will be invoked with the corresponding
+  // PresentationSessionInfo object.
   // If |default_presentation_url| is empty, the default presentation URL will
-  // be cleared.
+  // be cleared and the previously registered callback (if any) will be removed.
   virtual void SetDefaultPresentationUrl(
       int render_process_id,
       int render_frame_id,
-      const std::string& default_presentation_url) = 0;
+      const std::string& default_presentation_url,
+      const PresentationSessionStartedCallback& callback) = 0;

[mark a. foltz, 2015/10/20 20:15:25]

success_cb for consistency?

[imcheng, 2015/10/24 00:41:19]

Since there's no error_cb, I don't think we should call it success_cb.

 
   // Starts a new presentation session. The presentation id of the session will
   // be the default presentation ID if any or a generated one otherwise.
   // Typically, the embedder will allow the user to select a screen to show
   // |presentation_url|.
   // |render_process_id|, |render_frame_id|: ID of originating frame.
   // |presentation_url|: URL of the presentation.
   // |success_cb|: Invoked with session info, if presentation session started
   // successfully.
   // |error_cb|: Invoked with error reason, if presentation session did not
   // start.
   virtual void StartSession(
       int render_process_id,
       int render_frame_id,
       const std::string& presentation_url,
-      const PresentationSessionSuccessCallback& success_cb,
+      const PresentationSessionStartedCallback& success_cb,
       const PresentationSessionErrorCallback& error_cb) = 0;
 
   // Joins an existing presentation session. Unlike StartSession(), this
   // does not bring a screen list UI.
   // |render_process_id|, |render_frame_id|: ID for originating frame.
   // |presentation_url|: URL of the presentation.
   // |presentation_id|: The ID of the presentation to join.
   // |success_cb|: Invoked with session info, if presentation session joined
   // successfully.
   // |error_cb|: Invoked with error reason, if joining failed.
   virtual void JoinSession(
       int render_process_id,
       int render_frame_id,
       const std::string& presentation_url,
       const std::string& presentation_id,
-      const PresentationSessionSuccessCallback& success_cb,
+      const PresentationSessionStartedCallback& success_cb,
       const PresentationSessionErrorCallback& error_cb) = 0;
 
   // Close an existing presentation session.
   // |render_process_id|, |render_frame_id|: ID for originating frame.
   // |presentation_id|: The ID of the presentation to close.
   virtual void CloseSession(int render_process_id,
                             int render_frame_id,
                             const std::string& presentation_id) = 0;
 
   // Listen for messages for a presentation session.
@@ skipping 25 matching lines @@
   // there is a state change.
   virtual void ListenForSessionStateChange(
       int render_process_id,
       int render_frame_id,
       const SessionStateChangedCallback& state_changed_cb) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_PRESENTATION_SERVICE_DELEGATE_H_