[PresentationAPI] Added on-session-message handler.

content/renderer/presentation/presentation_session_client.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_RENDERER_PRESENTATION_PRESENTATION_SESSION_CLIENT_H_
 #define CONTENT_RENDERER_PRESENTATION_PRESENTATION_SESSION_CLIENT_H_
 
 #include "base/compiler_specific.h"
 #include "content/common/content_export.h"
 #include "content/common/presentation/presentation_service.mojom.h"
 #include "third_party/WebKit/public/platform/modules/presentation/WebPresentationSessionClient.h"
 
 namespace content {
 
 // PresentationSessionClient is passed to the Blink layer if presentation
 // session has been created successfully. Owned by the callback.
 class CONTENT_EXPORT PresentationSessionClient
     : public NON_EXPORTED_BASE(blink::WebPresentationSessionClient) {
  public:
   explicit PresentationSessionClient(
         presentation::PresentationSessionInfoPtr session_info);
+  explicit PresentationSessionClient(const mojo::String& url,
+                                     const mojo::String& id);
   ~PresentationSessionClient() override;
 
   // WebPresentationSessionClient implementation.
   virtual blink::WebString getUrl();
   virtual blink::WebString getId();
 
  private:
   blink::WebString url_;
   blink::WebString id_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_PRESENTATION_PRESENTATION_SESSION_CLIENT_H_