Now we actually use the vsync signal to trigger work. Previously, we'd hit the
pipeline depth limit too early and fall back to swap buffers-triggered
rendering.
Also, rename Vsync to VSync on recommendation from jamesr.
Instead of using back pressure from swap buffers to drive the engine, this
patch using the vsync signal from the Android framework. We still respect
back pressure from swap buffers if we get too far ahead.
This patch contains some minor improvements to the network service:
- We now cache the connection to the network service so we don't need to spin
it up for each request.
- We now manage the lifetime of NetworkServiceImpl in the same way as other
services.
Also, update the workbench sky_tools dependency to the latest version.
