Refactor ActivityStatus to not store current

- Refactor ActivityStatus to expose application level visibility over activity visbility.
- Add a listener for the visibility of the Application (are any Activities visible?)

BUG=341231
NOTRY=true

Review URL: https://codereview.chromium.org/159173002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252679 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: e5c934a20f125922bbe2916402648fbd532c73d7
20 files changed
tree: 2984f3a505f2a4acc1960c294070203f8dbb4121
  1. base/
  2. build/
  3. components/
  4. dbus/
  5. ipc/
  6. mojo/
  7. testing/
  8. third_party/
  9. ui/