[ios] Implemented -[ShellEarlGrey loadURL:].

ios/web/public/test/earl_grey/js_test_util.h

Index: ios/web/public/test/earl_grey/js_test_util.h
diff --git a/ios/web/public/test/earl_grey/js_test_util.h b/ios/web/public/test/earl_grey/js_test_util.h
new file mode 100644
index 0000000000000000000000000000000000000000..b1a26f5c35155d45ed222a8a3844ec14e177f0a7
--- /dev/null
+++ b/ios/web/public/test/earl_grey/js_test_util.h
@@ -0,0 +1,30 @@
+// 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.
+
+#ifndef IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_
+#define IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_
+
+#import <Foundation/Foundation.h>
+
+#import "ios/web/public/web_state/web_state.h"
+
+namespace web {
+
+// Waits until the Window ID has been injected and the page is thus ready to
+// respond to JavaScript injection. Fails on timeout or if unrecoverable error

[baxley, 2016/09/14 15:43:26]

Should we clarify that it fails with a GREYAssert, so the caller knows what to
expect?

[Eugene But (OOO till 7-30), 2016/09/14 16:25:29]

Done.

+// (such as no web view) occurs.
+void WaitUntilWindowIdInjected(WebState* web_state);
+
+// Executes |javascript| on the given |web_state|, and waits until execution is
+// completed. If |out_error| is not nil, it is set to the error resulting from
+// the execution, if one occurs. The return value is the result of the
+// JavaScript execution. If the script execution is timed out, then this method
+// fails.

[baxley, 2016/09/14 15:43:26]

Similar to the last comment, do you think it's good to mention GREYAssert (if
that's what the implementation does, based on my other comment)

[Eugene But (OOO till 7-30), 2016/09/14 16:25:29]

Done.

+id ExecuteJavaScript(WebState* web_state,
+                     NSString* javascript,
+                     NSError** out_error);
+
+}  // namespace web
+
+#endif  // IOS_WEB_PUBLIC_TEST_EARL_GREY_JS_TEST_UTIL_H_