Revert of Move preferred scrollbar style preference change listening from renderer to browser, 3 of 3. (https://codereview.chromium.org/136333009/)

Reason for revert:
This seems to be causing a mac_rel failure and is blocking blink roll.

see here: http://build.chromium.org/p/tryserver.chromium/builders/mac_rel/builds/215993/steps/content_browsertests/logs/stdio


Original issue's description:
> Move preferred scrollbar style preference change listening from renderer to browser, 3 of 3.
> 
> This removes the preferred style listener from Blink, now that the browser
> sends the value when it changes over IPC.
> 
> BUG=306348
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=165714

TBR=jamesr@chromium.org,thakis@chromium.org,rsesek@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=306348

Review URL: https://codereview.chromium.org/147193002

git-svn-id: svn://svn.chromium.org/blink/trunk@165774 bbb929c8-8fbe-4397-9dbb-9b2b20218538