Remove the implementation of multiple-profile sampling

The reasons for this change are:
1) this functionality is never used;
2) it's redundant as ThreadProfiler supports periodic sampling.

This change reduces the code complexity and makes the upcoming code
refactoring to support profiling task execution much easier.

Bug: 851163
Change-Id: I16fc0cfeb1fbb7d9ff9522f92b4162ed65367e44
Reviewed-on: https://chromium-review.googlesource.com/1093473
Reviewed-by: Mike Wittman <wittman@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566203}
15 files changed