[MediaRouter] Adds GetPresentationServiceDelegate impl to ChromeContentBrowserClient

chrome/browser/media/router/presentation_service_delegate_impl.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 CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SERVICE_DELEGATE_IMPL_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SERVICE_DELEGATE_IMPL_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 28 matching lines @@
 // Router to handle presentation API calls forwarded from
 // PresentationServiceImpl. In addition, it also
 // provides default presentation URL that is required for creating
 // browser-initiated sessions.
 // It is scoped to the lifetime of a WebContents, and is managed by the
 // associated WebContents.
 class PresentationServiceDelegateImpl
     : public content::WebContentsUserData<PresentationServiceDelegateImpl>,
       public content::PresentationServiceDelegate {
  public:
+  // Retrieves the instance of PresentationServiceDelegateImpl that was attached
+  // to the specified WebContents.  If no instance was attached, creates one,
+  // and attaches it to the specified WebContents.
+  static PresentationServiceDelegateImpl* GetOrCreateForWebContents(
+      content::WebContents* web_contents);
+
   ~PresentationServiceDelegateImpl() override;
 
   // content::PresentationServiceDelegate implementation.
   void AddObserver(
       int render_process_id,
       int render_frame_id,
       content::PresentationServiceDelegate::Observer* observer) override;
   void RemoveObserver(int render_process_id, int render_frame_id) override;
   bool AddScreenAvailabilityListener(
       int render_process_id,
@@ skipping 105 matching lines @@
   scoped_ptr<PresentationFrameManager> frame_manager_;
 
   base::WeakPtrFactory<PresentationServiceDelegateImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PresentationServiceDelegateImpl);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_SERVICE_DELEGATE_IMPL_H_