The current value of kDefaultDescriptorPoolMaxSets is 2048, which
allocates too much memory on a Pixel device, causing Android's low
memory killer to terminate dEQP (leading to a test failure). This change
reduces the value of kDefaultDescriptorPoolMaxSets to 128 to reduce the
memory usage during the test. We suspect a later change may be required
to dynamically grow the descriptor pools and update the recycling
behavior.

This change also exposed a bug in the ANGLERenderTest where the swap()
call was being skipped for null devices. This was causing code that
ANGLE requires to clean up and re-use resources to be skipped. Enabling
the swap() call fixes this issue as well as improves performance for
the test overall. This does make comparing old performance values to new
difficult (if not entirely incorrect), so take care when doing so.

dEQP-EGL.functional.multicontext.non_shared_clear

Bug: angleproject:3056
Bug: angleproject:3135
Change-Id: Ibdfd3a5eb436a7ba4e45002ebef5809afe777af1
Reviewed-on: https://chromium-review.googlesource.com/c/1470830
Commit-Queue: Tim Van Patten <timvp@google.com>
Reviewed-by: Tobin Ehlis <tobine@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>