[Mac] Factor out keyboard shortcut handling from ChromeEventProcessingWindow.

ui/views/examples/webview_example.h

 // Copyright (c) 2012 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 UI_VIEWS_EXAMPLES_WEBVIEW_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_WEBVIEW_EXAMPLE_H_
 
 #include "base/macros.h"
+#include "content/public/browser/web_contents_delegate.h"
+#include "ui/views/controls/webview/unhandled_keyboard_event_handler.h"
 #include "ui/views/examples/example_base.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace views {
 class WebView;
 
 namespace examples {
 
-class WebViewExample : public ExampleBase {
+class WebViewExample : public ExampleBase, public content::WebContentsDelegate {
  public:
   explicit WebViewExample(content::BrowserContext* browser_context);
   ~WebViewExample() override;
 
   // ExampleBase:
   void CreateExampleView(View* container) override;
 
+  // content::WebContentsDelegate:
+  void HandleKeyboardEvent(
+      content::WebContents* source,
+      const content::NativeWebKeyboardEvent& event) override;
+
  private:
   WebView* webview_;
   content::BrowserContext* browser_context_;
+  views::UnhandledKeyboardEventHandler unhandled_keyboard_event_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(WebViewExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_WEBVIEW_EXAMPLE_H_