Files.app: Enable VolumeManager to find a volume by using any paths.

Currently VolumeManager can find a volume by using only mount paths.  But after
introducing the multiprofile functionality, mount paths cannot be expected in
advance. This CL enables the getVolume method of VolumeManager to find a volume by
using any paths.

BUG=302090
TEST=manually

Review URL: https://codereview.chromium.org/64753005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236746 0039d316-1c4b-4281-b951-d872f2087c98
Move PolicyBundle into components/policy/.

This facilitates the refactoring of chrome/browser/policy into a layered
component.

Depends on https://codereview.chromium.org/78763002/

BUG=271392

Review URL: https://codereview.chromium.org/78823004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236747 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236747