Route LayerTreeHostImplClient::SetNeedsRedrawOnImplThread() through LayerTreeHostImpl::SetNeedsRedraw()

This CL replaces all the direct calls on
LayerTreeHostImplClient::SetNeedsRedrawOnImplThread() within LayerTreeHostImpl
with LayerTreeHostImpl::SetNeedsRedraw(). So we have a central place to
track when the needs redraw is set.

BUG=246034
TEST=No functional change.

Review URL: https://codereview.chromium.org/95823002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237863 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237863