Rename DocumentMarkerController::RemoveMarkers() to RemoveMarkersInRange()

yosin pointed out that it's confusing to have so many methods named
RemoveMarkers():
https://codereview.chromium.org/2820633002#msg30

This is the first of several renaming CLs I'm going to upload

BUG=707867

Review-Url: https://codereview.chromium.org/2830213002
Cr-Commit-Position: refs/heads/master@{#466302}
6 files changed