Upstream the iOS web_shell and supporting code

ios/web/shell/shell_main_delegate.mm

Index: ios/web/shell/shell_main_delegate.mm
diff --git a/ios/web/shell/shell_main_delegate.mm b/ios/web/shell/shell_main_delegate.mm
new file mode 100644
index 0000000000000000000000000000000000000000..97db23d059521eadf3048e9741fdac69ed41cd55
--- /dev/null
+++ b/ios/web/shell/shell_main_delegate.mm
@@ -0,0 +1,22 @@
+// Copyright 2014 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.
+
+#include "ios/web/shell/shell_main_delegate.h"
+
+#include "ios/web/shell/shell_web_client.h"
+
+namespace web {
+
+ShellMainDelegate::ShellMainDelegate() {
+}
+
+ShellMainDelegate::~ShellMainDelegate() {
+}
+
+void ShellMainDelegate::BasicStartupComplete() {
+  web_client_.reset(new ShellWebClient());
+  web::SetWebClient(web_client_.get());
+}
+
+}  // namespace web