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

ios/web/web_state/web_state_observer_bridge_unittest.mm

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/public/web_state/web_state_observer_bridge.h"
 
-#import "base/mac/scoped_nsobject.h"
 #include "base/memory/ptr_util.h"
 #include "ios/web/public/favicon_url.h"
 #import "ios/web/public/test/fakes/crw_test_web_state_observer.h"
 #import "ios/web/public/test/fakes/test_web_state.h"
 #import "ios/web/public/web_state/web_state_observer_bridge.h"
 #import "ios/web/web_state/navigation_context_impl.h"
 #include "net/http/http_response_headers.h"
 #include "testing/platform_test.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 namespace {
 const char kRawResponseHeaders[] =
     "HTTP/1.1 200 OK\0"
     "Content-Length: 450\0"
     "Connection: keep-alive\0";
 }  // namespace
 
 // Test fixture to test WebStateObserverBridge class.
 class WebStateObserverBridgeTest : public PlatformTest {
  protected:
   WebStateObserverBridgeTest()
       : observer_([[CRWTestWebStateObserver alloc] init]),
         bridge_(base::MakeUnique<WebStateObserverBridge>(&test_web_state_,
-                                                         observer_.get())),
+                                                         observer_)),
         response_headers_(new net::HttpResponseHeaders(
             std::string(kRawResponseHeaders, sizeof(kRawResponseHeaders)))) {}
 
   web::TestWebState test_web_state_;
-  base::scoped_nsobject<CRWTestWebStateObserver> observer_;
+  CRWTestWebStateObserver* observer_;
   std::unique_ptr<WebStateObserverBridge> bridge_;
   scoped_refptr<net::HttpResponseHeaders> response_headers_;
 };
 
 // Tests |webState:didPruneNavigationItemsWithCount:| forwarding.
 TEST_F(WebStateObserverBridgeTest, NavigationItemsPruned) {
   ASSERT_FALSE([observer_ navigationItemsPrunedInfo]);
 
   bridge_->NavigationItemsPruned(1);
 
@@ skipping 228 matching lines @@
 // Tests |webState:webStateDidStartLoading:| forwarding.
 TEST_F(WebStateObserverBridgeTest, DidStartLoading) {
   ASSERT_FALSE([observer_ startLoadingInfo]);
 
   bridge_->DidStartLoading();
   ASSERT_TRUE([observer_ startLoadingInfo]);
   EXPECT_EQ(&test_web_state_, [observer_ startLoadingInfo]->web_state);
 }
 
 }  // namespace web