title: How Layer's Buffer is mapped to Framebuffer in Android SurfaceFlinger
body: <p>when Surface is created, there is a buffer associated with it, which is used to hold all canvas data related to this surface. And there could be multiple surafce created at a time in android application. </p>
  
  <p><strong>So my doubt it, as there is limited number of framebuffer like 3, how each surface's data is mapped to to final framebuffer</strong> which will be updated ? </p>