Enable lost URL detection in the Physical Web scanner

ios/chrome/common/physical_web/physical_web_request.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 IOS_CHROME_COMMON_PHYSICAL_WEB_PHYSICAL_WEB_REQUEST_H_
 #define IOS_CHROME_COMMON_PHYSICAL_WEB_PHYSICAL_WEB_REQUEST_H_
 
 #import <Foundation/Foundation.h>
 
 #import "ios/chrome/common/physical_web/physical_web_types.h"
 
 // This class will perform a metadata service web request to expand the given
 // URL and return the metadata of the web page such as the title.
 
 @interface PhysicalWebRequest : NSObject
 
 // Initializes a metadata service web request with information about the
 // physical web device.
 - (instancetype)initWithDevice:(PhysicalWebDevice*)device
     NS_DESIGNATED_INITIALIZER;
 
 - (instancetype)init NS_UNAVAILABLE;
 
+// Returns the URL sent in the query to the Physical Web service.
+- (NSURL*)requestURL;
+
 // Starts the request and call the given |block| when finished.
 // |block| should not be nil.
 // If an error occurred, the block will be called with a non-nil error.
 // When no error occurred, the result will be available in a PhysicalWebDevice
 // data structure.
 - (void)start:(physical_web::RequestFinishedBlock)block;
 
 // Cancels the request.
 - (void)cancel;
 
 @end
 
 #endif  // IOS_CHROME_COMMON_PHYSICAL_WEB_PHYSICAL_WEB_REQUEST_H_