Implement Physical Web listener registration

ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.h

 // Copyright 2016 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 IOS_CHROME_COMMON_PHYSICAL_WEB_IOS_CHROME_PHYSICAL_WEB_DATA_SOURCE_H_
 #define IOS_CHROME_COMMON_PHYSICAL_WEB_IOS_CHROME_PHYSICAL_WEB_DATA_SOURCE_H_
 
 #include "base/macros.h"
 #import "base/mac/scoped_nsobject.h"
-#include "components/physical_web/data_source/physical_web_data_source.h"
+#include "components/physical_web/data_source/physical_web_data_source_impl.h"
 
 namespace base {
 class ListValue;
 }
 class PhysicalWebListener;
 
 @class PhysicalWebScanner;
 
 // iOS implementation of PhysicalWebDataSource
-class IOSChromePhysicalWebDataSource : public PhysicalWebDataSource {
+class IOSChromePhysicalWebDataSource : public PhysicalWebDataSourceImpl {
  public:
   IOSChromePhysicalWebDataSource();
   ~IOSChromePhysicalWebDataSource() override;
 
   // Starts scanning for Physical Web URLs. If |network_request_enabled| is
   // true, discovered URLs will be sent to a resolution service.
   void StartDiscovery(bool network_request_enabled) override;
 
   // Stops scanning for Physical Web URLs and clears cached URL content.
   void StopDiscovery() override;
 
   // Returns a list of resolved URLs and associated page metadata. If network
   // requests are disabled, the list will be empty.
   std::unique_ptr<base::ListValue> GetMetadata() override;
 
   // Returns boolean |true| if network requests are disabled and there are one
   // or more discovered URLs that have not been sent to the resolution service.
   bool HasUnresolvedDiscoveries() override;
 
-  // Register for changes to Physical Web URLs and associated page metadata.
-  void RegisterListener(PhysicalWebListener* physical_web_listener) override;
-
-  // Unregister for changes to Physical Web URLs and associated page metadata.
-  void UnregisterListener(PhysicalWebListener* physical_web_listener) override;
-
  private:
   // Scanner for nearby Physical Web URL devices.
   base::scoped_nsobject<PhysicalWebScanner> scanner_;
 
   DISALLOW_COPY_AND_ASSIGN(IOSChromePhysicalWebDataSource);
 };
 
 #endif  // IOS_CHROME_COMMON_PHYSICAL_WEB_IOS_CHROME_PHYSICAL_WEB_DATA_SOURCE_H_