Add unittest to test CWVWebView.

ios/web_view/test/chrome_web_view_test.h

+// 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.
+
+#ifndef IOS_WEB_VIEW_TEST_CHROME_WEB_VIEW_TEST_H_
+#define IOS_WEB_VIEW_TEST_CHROME_WEB_VIEW_TEST_H_
+
+#include "testing/platform_test.h"
+
+@class CWVWebView;
+@class NSURL;
+
+class ChromeWebViewTest : public PlatformTest {
+ protected:
+  ChromeWebViewTest();
+  ~ChromeWebViewTest() override;
+
+  // Loads |URL| in |web_view|.

[Eugene But (OOO till 7-30), 2017/05/19 18:39:49]

Please document that this method waits until URL is loaded.

[michaeldo, 2017/05/23 16:20:52]

Done.

+  void LoadURL(CWVWebView* web_view, NSURL* URL);
+
+  // Waits until |web_view| stops loading.

[Eugene But (OOO till 7-30), 2017/05/19 18:39:49]

Please document what happens on timeout.

[michaeldo, 2017/05/23 16:20:52]

Done.

+  void WaitForPageLoadCompletion(CWVWebView* web_view);
+
+  // PlatformTest methods.
+  void SetUp() override;
+  void TearDown() override;
+};
+
+#endif  // IOS_WEB_VIEW_TEST_CHROME_WEB_VIEW_TEST_H_