[ObjC ARC] Converts ios/chrome/browser/web:eg_tests to ARC.

ios/chrome/browser/web/cache_egtest.mm

Index: ios/chrome/browser/web/cache_egtest.mm
diff --git a/ios/chrome/browser/web/cache_egtest.mm b/ios/chrome/browser/web/cache_egtest.mm
index 9704f1575058de099733f1476c31ee2132b8d091..90c3926ba147d77369648864ec0836b91c3e0786 100644
--- a/ios/chrome/browser/web/cache_egtest.mm
+++ b/ios/chrome/browser/web/cache_egtest.mm
@@ -4,7 +4,6 @@
 
 #import <EarlGrey/EarlGrey.h>
 
-#import "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "components/content_settings/core/browser/host_content_settings_map.h"
@@ -26,6 +25,10 @@
 #include "ios/web/public/test/response_providers/html_response_provider.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using chrome_test_util::WebViewContainingText;
 using web::test::HttpServer;
 
@@ -157,8 +160,8 @@ class ScopedBlockPopupsPref {
 // Reloads the web view and waits for the loading to complete.
 // TODO(crbug.com/638674): Evaluate if this can move to shared code
 - (void)reloadPage {
-  base::scoped_nsobject<GenericChromeCommand> reloadCommand(
-      [[GenericChromeCommand alloc] initWithTag:IDC_RELOAD]);
+  GenericChromeCommand* reloadCommand =
+      [[GenericChromeCommand alloc] initWithTag:IDC_RELOAD];
   chrome_test_util::RunCommandWithActiveViewController(reloadCommand);
 
   [ChromeEarlGrey waitForPageToFinishLoading];
@@ -167,8 +170,8 @@ class ScopedBlockPopupsPref {
 // Navigates back to the previous webpage.
 // TODO(crbug.com/638674): Evaluate if this can move to shared code.
 - (void)goBack {
-  base::scoped_nsobject<GenericChromeCommand> backCommand(
-      [[GenericChromeCommand alloc] initWithTag:IDC_BACK]);
+  GenericChromeCommand* backCommand =
+      [[GenericChromeCommand alloc] initWithTag:IDC_BACK];
   chrome_test_util::RunCommandWithActiveViewController(backCommand);
 
   [ChromeEarlGrey waitForPageToFinishLoading];