Skip TestingBrowserProcess creation in browser_tests

Introduce ChromeUnitTestSuite, move unit test stub service creation there.

Previously we created a TestingBrowserProcess at browser_test startup, then
destroyed it before creating a real BrowserProcessImpl. This caused the
ExtensionsBrowserClient to be created twice and caused problems with
notification observers on a NotificationService that was deleted.

BUG=326182
TEST=unit_tests, browser_tests

Review URL: https://codereview.chromium.org/107333002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239527 0039d316-1c4b-4281-b951-d872f2087c98
Cast: Updating tests

1. Cast Sender app: Switching from Sleep to a delayed task on a designated thread.
2. Properly setting audio closure to make sure that the frame is alive for the required duration.

Can only be committed after: https://chromiumcodereview.appspot.com/106183005/ 

BUG=323703

Review URL: https://codereview.chromium.org/108403004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239528 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239527
[cr tool] Fixing init with no arguments failing

BUG=313727

Review URL: https://codereview.chromium.org/110453002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239529 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239529