Cancel any pending speech recognitions when the dispatcher host terminates.

I have not added a new test for this because the existing test is flaky and
didn't seem right to add another flaky test like that. Instead I've added a TODO
to add a browser test for this case once the flaky test has been fixed.

BUG=none
TEST=manual

Review URL: http://codereview.chromium.org/6358007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@71956 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed