Move some method impls from DocumentMarkerController.cpp to final place

In https://codereview.chromium.org/2896703003, I'm splitting off some code in
some DocumentMarkerController methods into new methods in
TextMatchMarkerListImpl, but leaving the implementations of the new methods in
DocumentMarkerController.cpp to make that CL smaller. In this CL, I'm moving
these implementations to their final location in TextMatchMarkerListImpl.cpp.

I'm also combining the static method UpdateMarkerRenderedRect() in
DocumentMarkerController into
TextMatchMarkerListImpl::UpdateMarkerRenderedRectIfNeeded().

BUG=707867

Review-Url: https://codereview.chromium.org/2900573002
Cr-Commit-Position: refs/heads/master@{#474599}
2 files changed