Rename DMC::SetMarkersActive() to SetTextMatchMarkersActive()

Rename DocumentMarkerController::SetMarkersActive() to
SetTextMatchMarkersActive(). The current name of this method is confusing since
only TextMatch markers can be active or inactive.

I'm also fixing a PossiblyHasMarkers() check to be more specific (checking for
TextMatch markers instead of all types).

BUG=707867

Review-Url: https://codereview.chromium.org/2897493002
Cr-Commit-Position: refs/heads/master@{#473099}
8 files changed