Pass Physical Web metadata through a struct

components/physical_web/data_source/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 COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_
 #define COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_
 
 #include <memory>
+#include <string>
+#include <vector>
+#include "base/time/time.h"
+#include "url/gurl.h"
 
 namespace base {
 class ListValue;
 }
 
 namespace physical_web {
 
 class PhysicalWebListener;
 
 // Dictionary keys for reading Physical Web URL metadata.
+// TODO(cco3): Remove these when we are no longer dependent.
 extern const char kDescriptionKey[];
 extern const char kDistanceEstimateKey[];
 extern const char kGroupIdKey[];
 extern const char kIconUrlKey[];
 extern const char kResolvedUrlKey[];
 extern const char kScanTimestampKey[];
 extern const char kScannedUrlKey[];
 extern const char kTitleKey[];
 
+// Metadata struct for associating data with Physical Web URLs.
+struct Metadata {

[mattreynolds, 2016/12/09 00:10:03]

We should comment on which fields are optional. IIRC, at the PWS level the
scanned_url and resolved_url are required, and at least one of title or
description is required. On iOS we only set scanned_url, resolved_url, icon_url,
title, and description.

distance_estimate should probably be optional, maybe we should document it as
returning -1.0 when no distance estimate is available? (what do we do now?)

icon_url is definitely optional, group_id and scan_timestamp should be required
(but currently aren't).

+  Metadata();
+  Metadata(const Metadata& other);
+  ~Metadata();
+  // The URL broadcasted by the beacon and scanned by the client device.
+  GURL scanned_url;
+  // The URL that the scanned_url redirects to.
+  // This is the URL that users should be directed to.
+  GURL resolved_url;
+  // The favicon URL.
+  GURL icon_url;
+  // The title of the web page.
+  std::string title;
+  // The description of the web page.
+  std::string description;
+  // An identifier that associates multiple resolved URLs.  If two URLs have
+  // the same group id, only one should be shown (typically, the one with the
+  // smallest distance estimate).
+  std::string group_id;
+  // The estimated distance between the user and the Physical Web device (e.g.,
+  // beacon) in meters.
+  double distance_estimate;
+  // The timestamp corresponding to when this URL was last scanned.
+  base::Time scan_timestamp;
+};
+
+using MetadataList = std::vector<Metadata>;
+
 // Helper class for accessing Physical Web metadata and controlling the scanner.
 class PhysicalWebDataSource {
  public:
   virtual ~PhysicalWebDataSource() {}
 
   // Starts scanning for Physical Web URLs. If |network_request_enabled| is
   // true, discovered URLs will be sent to a resolution service.
   virtual void StartDiscovery(bool network_request_enabled) = 0;
 
   // Stops scanning for Physical Web URLs and clears cached URL content.
   virtual void StopDiscovery() = 0;
 
   // Returns a list of resolved URLs and associated page metadata. If network
   // requests are disabled or if discovery is not active, the list will be
   // empty. The method can be called at any time to receive the current metadata
   // list.
+  virtual std::unique_ptr<MetadataList> GetMetadataList() = 0;
+
+  // Returns a list of resolved URLs and associated page metadata. If network
+  // requests are disabled or if discovery is not active, the list will be
+  // empty. The method can be called at any time to receive the current metadata
+  // list.
+  // DEPRECATED
+  // TODO(cco3): Remove this when we are no longer dependent on it.
   virtual std::unique_ptr<base::ListValue> GetMetadata() = 0;
 
   // 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.
   // The method can be called at any time to check for unresolved discoveries.
   // If discovery is inactive or network requests are enabled, it will always
   // return false.
   virtual bool HasUnresolvedDiscoveries() = 0;
 
   // Register for changes to Physical Web URLs and associated page metadata.
   virtual void RegisterListener(PhysicalWebListener* physical_web_listener) = 0;
 
   // Unregister for changes to Physical Web URLs and associated page metadata.
   virtual void UnregisterListener(
       PhysicalWebListener* physical_web_listener) = 0;
 };
 
 }  // namespace physical_web
 
 #endif  // COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_