Move SplitString util into activity_replay_unittest.cc

The test for SplitString causes crashes deep within the C++ standard
library when the address sanitizer is enabled. Since it's only used in
one (disabled-by-default) test method, just move it into that file so
that it's no longer considered "production" code that needs test
coverage.

Ideally, if we still need this "test" (which appears to actually be code
for an old developer tool, tools/replay_log) and the ability to pass the
--only_honor flag, we'd refactor SplitString to use C++ std::string
methods, but since I'm not sure the replay_log tool will actually run at
the moment, I don't think it's worth investing the time unless we decide
we want it. I've filed https://issuetracker.google.com/326088876 to
track this issue.

BUG=b:318520168
TEST=cros_sdk env FEATURES="test" emerge-${BOARD} chromeos-base/gestures

Change-Id: I24632c2a78fcdba3fed27eadb981f0af5bb737e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/gestures/+/5318730
Commit-Queue: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Sean O'Brien <seobrien@chromium.org>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>
Tested-by: Harry Cutts <hcutts@chromium.org>
4 files changed