Start removing support for in-process NPAPI plugins. This was a debugging mode and was only supported by non-Aura Windows code.

BUG=330735
R=avi@chromium.org

Review URL: https://codereview.chromium.org/111613005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@242552 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 242552