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

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 5c4e5c861717cf32055d922dbe1507a0d8c95c75..ba0bf99d56bfddcb0da9e3790d335432d6d99c09 100644
--- a/content/public/browser/presentation_service_delegate.h
+++ b/content/public/browser/presentation_service_delegate.h
@@ -19,6 +19,10 @@ 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&,
                         PresentationConnectionState)>;
@@ -39,21 +43,10 @@ class CONTENT_EXPORT PresentationServiceDelegate {
     // 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() {}
@@ -101,13 +94,16 @@ class CONTENT_EXPORT PresentationServiceDelegate {
       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;
 
   // Starts a new presentation session. The presentation id of the session will
   // be the default presentation ID if any or a generated one otherwise.
@@ -123,7 +119,7 @@ class CONTENT_EXPORT PresentationServiceDelegate {
       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
@@ -139,7 +135,7 @@ class CONTENT_EXPORT PresentationServiceDelegate {
       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.