LocalSurfaceIdProvider to use default LSI

Previously, ParentLocalSurfaceIdAllocator would default to an invalid
LocalSurfaceId. A new LSI had to be explicitly allocated before the
normal behavior could use it.

With ParentLocalSurfaceIdAllocator now default initializing a valid LSI,
the various call sites no longer need to explicitly check for the
uninitialized state.

LocalSurfaceIdProvider is one of those call sites.

BUG=837030

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel
Change-Id: Ifec19249e74d2a705b54fec4d5d350ee435d87b0
Reviewed-on: https://chromium-review.googlesource.com/1036794
Commit-Queue: Chris Blume <cblume@chromium.org>
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555218}