[ios] Register test web schemes in WebTestSuite.

ios/web/test/web_test_suite.h

 // Copyright 2013 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.
 
 #ifndef IOS_WEB_TEST_WEB_TEST_SUITE_H_
 #define IOS_WEB_TEST_WEB_TEST_SUITE_H_
 
 #include "base/macros.h"
 #include "base/test/test_suite.h"
+#include "ios/web/public/test/scoped_testing_web_client.h"
 
 namespace web {
 
 class WebTestSuite : public base::TestSuite {
  public:
   WebTestSuite(int argc, char** argv);
   ~WebTestSuite() override;
 
  protected:
   void Initialize() override;
 
  private:
+  // Sets web client on construction and restores the original on destruction.
+  ScopedTestingWebClient web_client_;
 
   DISALLOW_COPY_AND_ASSIGN(WebTestSuite);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_TEST_WEB_TEST_SUITE_H_