DisplayDevices are now keyed of the wp<IBinder> the client uses.
DisplayID has now become DisplayType which is just used to identify
physical displays (as opposed to virtual displays such as wifi displays).
Change-Id: I0c5968f2c902dcd699a7e0afacf833ff070c12ea
Use only display tokens in the API to refer to new displays.
Don't require the caller to specify the display when creating
a surface (since in general a surface could be shown on
any display).
This is intended to be a minimum change just to update the API.
Note that SurfaceFlinger still uses DisplayID in a few places
internally that might cause some features not to work properly
when there are multiple displays (LayerScreenshot, for example).
Change-Id: I3d91eec2da406eefd97bcd53655d403ad865a7e6
