Move NativeWebKeyboardEvent to the content namespace.

chrome/browser/extensions/extension_host_mac.h

Index: chrome/browser/extensions/extension_host_mac.h
===================================================================
--- chrome/browser/extensions/extension_host_mac.h	(revision 137859)
+++ chrome/browser/extensions/extension_host_mac.h	(working copy)
@@ -17,9 +17,10 @@
                    const GURL& url, content::ViewType host_type) :
       ExtensionHost(extension, site_instance, url, host_type) {}
   virtual ~ExtensionHostMac();
+
  private:
   virtual void UnhandledKeyboardEvent(
-      const NativeWebKeyboardEvent& event) OVERRIDE;
+      const content::NativeWebKeyboardEvent& event) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionHostMac);
 };