[ObjC ARC] Converts parts of ios/web/webstate to ARC.

ios/web/web_state/ui/web_view_js_utils.mm

Index: ios/web/web_state/ui/web_view_js_utils.mm
diff --git a/ios/web/web_state/ui/web_view_js_utils.mm b/ios/web/web_state/ui/web_view_js_utils.mm
index 5036d489eb371de273863e7c89db989c77bab6ca..2ce156893861254bda746f6c36cbca1a37f39000 100644
--- a/ios/web/web_state/ui/web_view_js_utils.mm
+++ b/ios/web/web_state/ui/web_view_js_utils.mm
@@ -14,6 +14,10 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/values.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 
 // Converts result of WKWebView script evaluation to base::Value, parsing
@@ -30,7 +34,7 @@ std::unique_ptr<base::Value> ValueResultFromWKResult(id wk_result,
     return result;
   }
 
-  CFTypeID result_type = CFGetTypeID(wk_result);
+  CFTypeID result_type = CFGetTypeID((__bridge CFTypeRef)wk_result);
   if (result_type == CFStringGetTypeID()) {
     result.reset(new base::StringValue(base::SysNSStringToUTF16(wk_result)));
     DCHECK(result->IsType(base::Value::TYPE_STRING));