Split chromeos::CertLoader

CertLoader does both TPM token initialization and certificate loading
from the cert database. This extracts token initializetion in a separate
class.

BUG=315343

Review URL: https://codereview.chromium.org/132313004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246154 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246154
Avoid vector copy by passing as a const-reference.

This issue has been found by a linter.

R=gcasto@chromium.org

BUG=

Review URL: https://codereview.chromium.org/132333004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246156 0039d316-1c4b-4281-b951-d872f2087c98
Updates to hosting docs inline with policy changes

More specifically, Windows stable/beta users cannot download
extensions from local .crx. It has to be via Chrome Web
Store or else via Windows registry.

BUG=315154

Review URL: https://codereview.chromium.org/132433007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246157 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246156
SVN changes up to revision 246157