Refactor TestDataSource from being instantated to being passed in.

This is required by a future CL in this chain where we need to share a
data source between multiple Perfetto services.

Bug: 966047
Change-Id: I2e91c62b0fc7604ae2476b7201e7b53160e99651
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1625121
Commit-Queue: Stephen Nusko <nuskos@chromium.org>
Auto-Submit: Stephen Nusko <nuskos@chromium.org>
Reviewed-by: Eric Seckler <eseckler@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662660}
6 files changed