Added AddDownload communication path and observers

content/public/browser/background_fetch_client.h

 // Copyright 2017 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_BACKGROUND_FETCH_CLIENT_H_
 #define CONTENT_PUBLIC_BROWSER_BACKGROUND_FETCH_CLIENT_H_
 
 #include <string>
 
 #include "content/common/content_export.h"
@@ skipping 22 matching lines @@
     virtual void ResumeDownload(const std::string& registration_id) = 0;
 
    protected:
     virtual ~Delegate() {}
   };
 
   // The client will maintain a weak reference to |delegate|. The provider must
   // reset the delegate back to a `nullptr` when it's being destructed.
   virtual void SetDelegate(Delegate* delegate) = 0;
 
+  // Notify the client that a Background Fetch download has started, including
+  // all information needed to display a notification of the download.
+  virtual void AddDownload(const std::string& registration_id,
+                           const std::string& title,
+                           int64_t total_download_size) = 0;
+
  protected:
   virtual ~BackgroundFetchClient() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BACKGROUND_FETCH_CLIENT_H_