This adds a plugin selection policy for selecting which plugin is
allowed for a particular domain.

It is only used on ChromeOS.  It reads from a file that is installed
in a known location on ChromeOS, and uses that as it's policy.

When there are multiple plugins supporting the same mime-type, the
appropriate plugin file to load is now selected based on policy.

BUG=http://crosbug.com/7403
TEST=ran new unit test, tested on device.

Review URL: http://codereview.chromium.org/3717005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@62679 0039d316-1c4b-4281-b951-d872f2087c98
12 files changed