Use CanonicalCookie::FromStorage in CanonicalCookieFromSystemCookie.

This change is part of a larger cleanup effort to make the bare
CanonicalCookie constructor private. The factory method, FromStorage,
is used for loading cookies that have already entered the user agent's
storage model into a CanonicalCookie.

Bug: 1102874
Change-Id: Iaef8b2773e596c72073dc8bce61f6fd8253d0a66
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2504089Reviewed-by: Lily Chen <chlily@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Dylan Cutler <dylancutler@google.com>
Cr-Commit-Position: refs/heads/master@{#821748}

ios/net/cookies/system_cookie_util.mm

@@ -89,7 +89,7 @@ net::CanonicalCookie CanonicalCookieFromSystemCookie(
       same_site = net::CookieSameSite::NO_RESTRICTION;
   }
 
-  return net::CanonicalCookie(
+  return *std::move(net::CanonicalCookie::FromStorage(
       base::SysNSStringToUTF8([cookie name]),
       base::SysNSStringToUTF8([cookie value]),
       base::SysNSStringToUTF8([cookie domain]),
@@ -98,7 +98,7 @@ net::CanonicalCookie CanonicalCookieFromSystemCookie(
       base::Time(), [cookie isSecure], [cookie isHTTPOnly], same_site,
       // When iOS begins to support 'Priority' attribute, pass it
       // through here.
-      net::COOKIE_PRIORITY_DEFAULT);
+      net::COOKIE_PRIORITY_DEFAULT, net::CookieSourceScheme::kUnset));
 }
 
 void ReportGetCookiesForURLResult(SystemCookieStoreType store_type,