Do not build more iOS 13 specific code for cronet in system_cookie_util.mm

Bug: 1027274
Change-Id: I6013524cc2864f53d7d3f88f9ed7c21cbb87e6bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1930092
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Reviewed-by: Zhongyi Shi <zhongyi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#717962}

ios/net/cookies/system_cookie_util.mm

@@ -165,6 +165,9 @@ NSHTTPCookie* SystemCookieFromCanonicalCookie(
     [properties setObject:expiry forKey:NSHTTPCookieExpires];
   }
 
+// TODO(crbug.com/1027279): Remove this once Cronet can have
+// iOS 13 symbols.
+#if !BUILDFLAG(CRONET_BUILD)
   if (@available(iOS 13, *)) {
     // In iOS 13 sameSite property in NSHTTPCookie is used to specify the
     // samesite policy.
@@ -185,6 +188,7 @@ NSHTTPCookie* SystemCookieFromCanonicalCookie(
     }
     properties[NSHTTPCookieSameSitePolicy] = same_site;
   }
+#endif
 
   if (cookie.IsSecure())
     [properties setObject:@"Y" forKey:NSHTTPCookieSecure];