`availableFrameCount` tracks the number of frames that is avilable on the
`SurfaceTexture`, but haven't been used (by `updateTexImage()`) yet. Thus
semantically this counter should only be decremented after calling
`updateTexImage()`, not before it.
Also reworded `getPendingFrameCount()` javadoc, "external texture" is an
internal state that is not publicised anywhere.
PiperOrigin-RevId: 488765174
Public methods may only refer to public types in their signature. This
change ensures that by switching to a public supertype everywhere.
PiperOrigin-RevId: 485568625
Make it easier to support use of RGBA_101012 rather than RGBA_8888 for EGL
contexts, displays, and surfaces.
This tangentially supports adding HDR tests, by slightly simplifying the color
selection logic we'd have to add in HDR tests.
PiperOrigin-RevId: 482219428
