Pass Physical Web metadata through a struct

ios/chrome/common/physical_web/physical_web_scanner.h

Index: ios/chrome/common/physical_web/physical_web_scanner.h
diff --git a/ios/chrome/common/physical_web/physical_web_scanner.h b/ios/chrome/common/physical_web/physical_web_scanner.h
index 8873f3bf23535af4f0ffdf76930ed982b6a99c9f..354fdfc9c9cfd361b2ef71bd80d5700bf7ffe6f1 100644
--- a/ios/chrome/common/physical_web/physical_web_scanner.h
+++ b/ios/chrome/common/physical_web/physical_web_scanner.h
@@ -8,11 +8,17 @@
 #import <Foundation/Foundation.h>
 
 #include <memory>
+#include <vector>
 
 namespace base {
 class ListValue;
 }
 
+namespace physical_web {
+struct Metadata;
+using MetadataList = std::vector<Metadata>;
+}
+
 @protocol PhysicalWebScannerDelegate;
 
 // This class will scan for physical web devices.
@@ -57,6 +63,11 @@ class ListValue;
 // returned.
 - (std::unique_ptr<base::ListValue>)metadata;
 
+// Returns the metadata for all resolved physical web URLs. The returned value
+// will never be nil; if no metadata has been received then an empty list is
+// returned.
+- (std::unique_ptr<physical_web::MetadataList>)metadataList;
+
 @end
 
 @protocol PhysicalWebScannerDelegate<NSObject>