Convert //ios/web_view/internal to ARC.

ios/web_view/internal/criwv_web_view.mm

Index: ios/web_view/internal/criwv_web_view.mm
diff --git a/ios/web_view/internal/criwv_web_view.mm b/ios/web_view/internal/criwv_web_view.mm
index 2317387915ba38a8be867bf595237e17d20346e8..df2e9ea46dda5024b312324eb51bc0dc88d087ff 100644
--- a/ios/web_view/internal/criwv_web_view.mm
+++ b/ios/web_view/internal/criwv_web_view.mm
@@ -12,6 +12,7 @@
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/public/referrer.h"
+#import "ios/web/public/web_state/js/crw_js_injection_receiver.h"
 #import "ios/web/public/web_state/ui/crw_web_delegate.h"
 #import "ios/web/public/web_state/web_state.h"
 #import "ios/web/public/web_state/web_state_delegate_bridge.h"
@@ -26,8 +27,11 @@
 #include "ui/base/page_transition_types.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface CRIWVWebView ()<CRWWebStateDelegate, CRWWebStateObserver> {
-  id<CRIWVWebViewDelegate> _delegate;
   CRIWVWebViewConfiguration* _configuration;
   std::unique_ptr<web::WebState> _webState;
   std::unique_ptr<web::WebStateDelegateBridge> _webStateDelegate;