Use the URL passed to navigator.share().

third_party/WebKit/public/platform/modules/webshare/webshare.mojom

Index: third_party/WebKit/public/platform/modules/webshare/webshare.mojom
diff --git a/third_party/WebKit/public/platform/modules/webshare/webshare.mojom b/third_party/WebKit/public/platform/modules/webshare/webshare.mojom
index b96ec30b05e779597ad41a62a8717fb9ac14b05d..db5c1cd7c0b40c850889fe1cd9ff2280f7138b4c 100644
--- a/third_party/WebKit/public/platform/modules/webshare/webshare.mojom
+++ b/third_party/WebKit/public/platform/modules/webshare/webshare.mojom
@@ -5,11 +5,13 @@
 [JavaPackage="org.chromium.mojom.webshare"]
 module blink.mojom;
 
+import "url/mojo/url.mojom";
+
 interface ShareService {
   // The web contents has requested to send a share text action. Returns null on
   // success, or an error message on failure.
   // TODO(mgiuca): Return an error enum, instead of a string (so the actual
   // error messages are generated in a single place, rather than many service
   // handlers).
-  Share(string title, string text) => (string? error);
+  Share(string title, string text, url.mojom.Url url) => (string? error);
 };