[iOS] Remove remaining uses of UTF8String.

Bug: 659649
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I8813d293c71b1403f18368c60fa0a2435193cac4
Reviewed-on: https://chromium-review.googlesource.com/1016286
Commit-Queue: Stepan Khapugin <[email protected]>
Reviewed-by: Stepan Khapugin <[email protected]>
Cr-Commit-Position: refs/heads/master@{#551626}
diff --git a/ios/net/nsurlrequest_util.mm b/ios/net/nsurlrequest_util.mm
index f09b7b5..37309a0 100644
--- a/ios/net/nsurlrequest_util.mm
+++ b/ios/net/nsurlrequest_util.mm
@@ -5,6 +5,7 @@
 #include "ios/net/nsurlrequest_util.h"
 
 #include "base/strings/stringprintf.h"
+#include "base/strings/sys_string_conversions.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -18,9 +19,11 @@
       request.mainDocumentURL.absoluteString;
   return base::StringPrintf(
       "request: %s request.mainDocURL: %s",
-      urlAbsoluteString ? urlAbsoluteString.UTF8String : "[nil]",
-      mainDocumentURLAbsoluteString ?
-          mainDocumentURLAbsoluteString.UTF8String : "[nil]");
+      urlAbsoluteString ? base::SysNSStringToUTF8(urlAbsoluteString).c_str()
+                        : "[nil]",
+      mainDocumentURLAbsoluteString
+          ? base::SysNSStringToUTF8(mainDocumentURLAbsoluteString).c_str()
+          : "[nil]");
 }
 
 }  // namespace net