掌握PPAPI架构

要理解PPAPI插件的设计，先仔细阅读下面这些文章：

• Chromium's Process Models
• Chromium's Multi-Process Architecture
• Chromium's Plugin System
• Pepper Plugin System Implementation

理解了架构设计，再看代码层面的文档：

• [Important concepts for working with PPAPI](https://code.google.com/p/ppapi/wiki/Co