[ObjC ARC] Converts ios/web/public/test:test to ARC.

ios/web/public/test/web_test_with_web_state.mm

 // Copyright 2016 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/test/web_test_with_web_state.h"
 
 #include "base/run_loop.h"
 #include "base/strings/sys_string_conversions.h"
 #import "base/test/ios/wait_util.h"
 #import "ios/web/navigation/navigation_manager_impl.h"
 #include "ios/web/public/web_state/url_verification_constants.h"
 #include "ios/web/public/web_state/web_state_observer.h"
 #import "ios/web/web_state/ui/crw_web_controller.h"
 #import "ios/web/web_state/web_state_impl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace {
 // Returns CRWWebController for the given |web_state|.
 CRWWebController* GetWebController(web::WebState* web_state) {
   web::WebStateImpl* web_state_impl =
       static_cast<web::WebStateImpl*>(web_state);
   return web_state_impl->GetWebController();
 }
 }  // namespace
 
 namespace web {
@@ skipping 94 matching lines @@
   } while (activitySeen);
   messageLoop->RemoveTaskObserver(this);
 }
 
 void WebTestWithWebState::WaitForCondition(ConditionBlock condition) {
   base::test::ios::WaitUntilCondition(condition, true,
                                       base::TimeDelta::FromSeconds(10));
 }
 
 id WebTestWithWebState::ExecuteJavaScript(NSString* script) {
-  __block base::scoped_nsprotocol<id> executionResult;
+  __block id executionResult;
   __block bool executionCompleted = false;
   [GetWebController(web_state())
       executeJavaScript:script
       completionHandler:^(id result, NSError* error) {
-        executionResult.reset([result copy]);
+        executionResult = [result copy];
         executionCompleted = true;
       }];
   base::test::ios::WaitUntilCondition(^{
     return executionCompleted;
   });
-  return [[executionResult retain] autorelease];
+  return executionResult;
 }
 
 void WebTestWithWebState::DestroyWebState() {
   web_state_.reset();
 }
 
 std::string WebTestWithWebState::BaseUrl() const {
   web::URLVerificationTrustLevel unused_level;
   return web_state()->GetCurrentURL(&unused_level).spec();
 }
 
 web::WebState* WebTestWithWebState::web_state() {
   return web_state_.get();
 }
 
 const web::WebState* WebTestWithWebState::web_state() const {
   return web_state_.get();
 }
 
 void WebTestWithWebState::WillProcessTask(const base::PendingTask&) {
   // Nothing to do.
 }
 
 void WebTestWithWebState::DidProcessTask(const base::PendingTask&) {
   processed_a_task_ = true;
 }
 
 }  // namespace web