Change the way lazy background pages shutdown.

The browser process now keeps a generic count of activity from the lazy background page. This will be used for all types of activity, such as outstanding events, resource requests, and API calls.

BUG=81752
TEST=no

Review URL: https://chromiumcodereview.appspot.com/9447042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@123821 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed