Match only prefixes of histogram names.

Fix the bug that HistogramTester::GetTotalCountsForPrefix returns histograms
which contain the query string as substrings, not as prefixes.

Additionally, omit explicit base:: namespace here and there, because the files
are already in this namespace.

BUG=659977

Review-Url: https://codereview.chromium.org/2628843002
Cr-Commit-Position: refs/heads/master@{#443620}


CrOS-Libchrome-Original-Commit: 63e22b6fcb629ebccc0f257de04bc8e7f4ef247c
3 files changed
tree: 1d0024c536e51a178fdffdc6916a2912839d9831
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. device/
  6. ipc/
  7. mojo/
  8. testing/
  9. third_party/
  10. ui/