Add a Physical Web data source

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 8f28f90ce857792e00dd7d513c5d1e28635c1a20..c147bc29bca7b3785ab8b5817e0fec4374e99c7b 100644
--- a/ios/chrome/common/physical_web/physical_web_scanner.h
+++ b/ios/chrome/common/physical_web/physical_web_scanner.h
@@ -7,7 +7,11 @@
 
 #import <Foundation/Foundation.h>
 
-@class PhysicalWebDevice;
+#include <memory>
+
+namespace base {
+class ListValue;
+}
 
 @protocol PhysicalWebScannerDelegate;
 
@@ -43,6 +47,11 @@
 // Returns a list of physical web devices (PhysicalWebDevice).
 - (NSArray*)devices;
 
+// 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<base::ListValue>)metadata;
+
 @end
 
 @protocol PhysicalWebScannerDelegate<NSObject>