[ios] Added API to enable/disable web usage for WebState.

ios/web/test/web_test.mm

 // Copyright 2012 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/test/web_test.h"
 
 #include <utility>
 
 #include "base/base64.h"
 #include "base/memory/ptr_util.h"
@@ skipping 53 matching lines @@
 
 WebTestWithWebController::~WebTestWithWebController() {}
 
 static int s_html_load_count;
 
 void WebTestWithWebController::SetUp() {
   WebTest::SetUp();
   web_state_impl_.reset(new WebStateImpl(GetBrowserState()));
   web_state_impl_->GetNavigationManagerImpl().InitializeSession(nil, nil, NO,
                                                                 0);
+  web_state_impl_->SetWebUsageEnabled(true);
   webController_.reset(web_state_impl_->GetWebController());
 
-  [webController_ setWebUsageEnabled:YES];
   // Force generation of child views; necessary for some tests.
   [webController_ triggerPendingLoad];
   s_html_load_count = 0;
 }
 
 void WebTestWithWebController::TearDown() {
   web_state_impl_.reset();
   WebTest::TearDown();
 }
 
@@ skipping 110 matching lines @@
 void WebTestWithWebController::DidProcessTask(
     const base::PendingTask& pending_task) {
   processed_a_task_ = true;
 }
 
 bool WebTestWithWebController::ResetPageIfNavigationStalled(
     NSString* load_check) {
   NSString* inner_html = EvaluateJavaScriptAsString(
       @"(document && document.body && document.body.innerHTML) || 'undefined'");
   if ([inner_html rangeOfString:load_check].location == NSNotFound) {
-    [webController_ setWebUsageEnabled:NO];
-    [webController_ setWebUsageEnabled:YES];
+    web_state_impl_->SetWebUsageEnabled(false);
+    web_state_impl_->SetWebUsageEnabled(true);
     [webController_ triggerPendingLoad];
     return true;
   }
   return false;
 }
 
 NSString* WebTestWithWebController::CreateLoadCheck() {
   return [NSString stringWithFormat:@"<p style=\"display: none;\">%d</p>",
                                     s_html_load_count++];
 }
 
 }  // namespace web