Upstream "nsurl_util.{h,mm}" from Chrome on iOS repository.

url/BUILD.gn

Index: url/BUILD.gn
diff --git a/url/BUILD.gn b/url/BUILD.gn
index ec15c438d98eb55d128d34f9129a74aa666ffb04..5473cb7fc0d8a476a31b04ea88ece307c7a72906 100644
--- a/url/BUILD.gn
+++ b/url/BUILD.gn
@@ -87,6 +87,13 @@ component("url") {
       "url_canon_icu_alternatives_android.h",
     ]
   }
+
+  if (is_mac || is_ios) {
+    sources += [
+      "mac/url_conversions.h",
+      "mac/url_conversions.mm",
+    ]
+  }
 }
 
 # TODO(dpranke): crbug.com/360936. Get this to build and run on Android.
@@ -130,5 +137,11 @@ if (!is_android) {
         "//third_party/icu:icuuc",
       ]
     }
+
+    if (is_mac || is_ios) {
+      sources += [
+        "mac/url_conversions_unittest.mm",
+      ]
+    }
   }
 }