app_shell: Extract extension runtime data from ExtensionService

This allows ExtensionHost to use the data when there is no ExtensionService, such as when running app_shell.

BUG=332982
TEST=Added unit test, existing extensions browser tests
TBR=msw@chromium.org for mechanical change to chrome/browser/ui/views/

Review URL: https://codereview.chromium.org/131743021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246449 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246449