Implement <appview> skeleton.

chrome/browser/guest_view/app_view/app_view_guest.cc

+// 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 "chrome/browser/guest_view/app_view/app_view_guest.h"
+
+// static
+const char AppViewGuest::Type[] = "appview";
+
+AppViewGuest::AppViewGuest(content::BrowserContext* browser_context,
+                           int guest_instance_id)
+    : GuestView<AppViewGuest>(browser_context, guest_instance_id) {
+}
+
+AppViewGuest::~AppViewGuest() {
+}
+
+void AppViewGuest::CreateWebContents(
+    const std::string& embedder_extension_id,
+    int embedder_render_process_id,
+    const base::DictionaryValue& create_params,
+    const WebContentsCreatedCallback& callback) {
+  // TODO(fsamuel): Create a WebContents with the appropriate SiteInstance here.
+  // After the WebContents has been created, call the |callback|.
+  // callback.Run(new_web_contents);
+}
+
+void AppViewGuest::DidAttachToEmbedder() {
+  // This is called after the guest process has been attached to a host
+  // element. This means that the host element knows how to route input
+  // events to the guest, and the guest knows how to get frames to the
+  // embedder.
+  // TODO(fsamuel): Perform the initial navigation here.
+}