Introduce WebViewGuestDelegate.

extensions/browser/guest_view/web_view/web_view_guest_delegate.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 "extensions/browser/guest_view/web_view/web_view_guest_delegate.h"
+
+namespace extensions {
+
+WebViewGuestDelegate::WebViewGuestDelegate() {
+}
+
+WebViewGuestDelegate::~WebViewGuestDelegate() {
+}
+
+double WebViewGuestDelegate::GetZoom() {
+  return 1.0;
+}
+
+GuestViewBase::Event* WebViewGuestDelegate::OnHandleContextMenu(
+    const content::ContextMenuParams& params) {
+  return NULL;
+}
+
+GuestViewBase::Event* WebViewGuestDelegate::OnSetZoom(
+    double zoom_factor,
+    const std::string& old_zoom_factor,
+    const std::string& new_zoom_factor,
+    const std::string& event_zoom_change) {
+  return NULL;
+}
+
+}  // namespace extensions