Added an annotation to label Integration tests.


An IntegrationTest label will be required for tests that may require
a greater timeout value than LargeTest allows. These tests will run
against real instances of other services (e.g. Search). They may use
command-line flags to change the backends that are being tested against.

BUG=None

Review URL: https://codereview.chromium.org/407173002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284821 0039d316-1c4b-4281-b951-d872f2087c98