Pass params by const & and use "CPU instead of "Cpu" naming. Also
prefer "ContextVk *contextVk" to "ContextVk *context".

Bug: angleproject:2464
Change-Id: I887de5b2e5494d14f0e9c7db269eb63744f2a3cf
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1771499Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>