it's safer this way because this object owns an
EGLSurface which cannot be easily reference-counted.
it also gives us the ability to sub-class it, which
we might want to do soon.
Change-Id: I07358bb052dc5a13b4f2196b2c2b6e6e94c4bb4f
- fix typo drawForSreenshot misspelled
- get rid of DisplayDeviceBase
- removed unused or unneeded code
- always pass a DisplayDevice to Layer methods that are called
on a per-display basis (to make it clear that this could be
called more than once per composition).
Change-Id: Id948b7e09fe5c06db0e42d40d6ed75dd095c7f44