[chrome.displaySource] DisplaySourceConnectionDelegate::Connection interface

extensions/browser/api/display_source/display_source_event_router.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 EXTENSIONS_BROWSER_API_DISPLAY_SOURCE_DISPLAY_SOURCE_EVENT_ROUTER_H_
 #define EXTENSIONS_BROWSER_API_DISPLAY_SOURCE_DISPLAY_SOURCE_EVENT_ROUTER_H_
 
 #include "base/macros.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "extensions/browser/api/display_source/display_source_connection_delegate.h"
 #include "extensions/browser/event_router.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 // Observe listeners to 'onSinksUpdated' events.
+// This class initiates/stops listening for the available sinks
+// by the DisplaySourceConnectionDelegate, depending on whether
+// there are existing listeners to 'onSinksUpdated' event.
 class DisplaySourceEventRouter
     : public KeyedService,
       public EventRouter::Observer,
       public DisplaySourceConnectionDelegate::Observer {
  public:
   static DisplaySourceEventRouter* Create(
       content::BrowserContext* browser_context);
 
   ~DisplaySourceEventRouter() override;
 
  private:
   explicit DisplaySourceEventRouter(content::BrowserContext* browser_context);
 
   // KeyedService overrides:
   void Shutdown() override;
 
   // EventRouter::Observer overrides:
   void OnListenerAdded(const EventListenerInfo& details) override;
   void OnListenerRemoved(const EventListenerInfo& details) override;
 
   // DisplaySourceConnectionDelegate::Observer overrides:
   void OnSinksUpdated(const DisplaySourceSinkInfoList& sinks) override;
+  void OnConnectionError(int sink_id,
+                         DisplaySourceErrorType type,
+                         const std::string& description) override {}
 
  private:
   void StartOrStopListeningForSinksChanges();
 
   content::BrowserContext* browser_context_;
   bool listening_;
 
   DISALLOW_COPY_AND_ASSIGN(DisplaySourceEventRouter);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_DISPLAY_SOURCE_DISPLAY_SOURCE_EVENT_ROUTER_H_