[Sampling profiler] Enable new profile builder at 50%

Server-side handling of the 1% of startup profiles has been validated.
Increase to 50% of all profiles to provide equivalent data for
comparison and validation of profile sizes.

Bug: 851163
Change-Id: Ib34239b7179939857667b8de9633b57ce247494f
Reviewed-on: https://chromium-review.googlesource.com/c/1342857
Commit-Queue: Mike Wittman <wittman@chromium.org>
Reviewed-by: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609414}
2 files changed