[ObjC ARC] Converts ios/web:ios_web_web_state_ui_unittests to ARC.

ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm

Index: ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm
diff --git a/ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm b/ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm
index d6988e898f382c4afe448d5ccd06143b919a92cd..85c77da7cccd543c327ecc6e29947aa1a4452ec4 100644
--- a/ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm
+++ b/ios/web/web_state/ui/crw_wk_navigation_states_unittest.mm
@@ -6,13 +6,16 @@
 
 #import <WebKit/WebKit.h>
 
-#import "base/mac/scoped_nsobject.h"
 #import "ios/web/web_state/navigation_context_impl.h"
 #include "net/http/http_response_headers.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 #include "url/gurl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 const char kTestUrl1[] = "https://test1.test/";
 const char kTestUrl2[] = "https://test2.test/";
@@ -30,10 +33,10 @@ class CRWWKNavigationStatesTest : public PlatformTest {
         states_([[CRWWKNavigationStates alloc] init]) {}
 
  protected:
-  base::scoped_nsobject<WKNavigation> navigation1_;
-  base::scoped_nsobject<WKNavigation> navigation2_;
-  base::scoped_nsobject<WKNavigation> navigation3_;
-  base::scoped_nsobject<CRWWKNavigationStates> states_;
+  WKNavigation* navigation1_;
+  WKNavigation* navigation2_;
+  WKNavigation* navigation3_;
+  CRWWKNavigationStates* states_;
 };
 
 // Tests |removeNavigation:| method.
@@ -103,7 +106,7 @@ TEST_F(CRWWKNavigationStatesTest, Context) {
       NavigationContextImpl::CreateNavigationContext(
           nullptr /*web_state*/, GURL(kTestUrl2),
           ui::PageTransition::PAGE_TRANSITION_GENERATED);
-  NSError* error = [[[NSError alloc] init] autorelease];
+  NSError* error = [[NSError alloc] init];
   context2->SetError(error);
   [states_ setContext:std::move(context2) forNavigation:navigation1_];
   EXPECT_FALSE([states_ contextForNavigation:navigation2_]);