Reland r56483 - Monitor network change in GoogleURLTracker

Reland r56483 - Monitor network change in GoogleURLTracker

It changes to fetch https://www.google.com/searchdomaincheck?format=domain&type=chrome
instead of checking http://www.google.com/ redirection.

Also show infobar if google domain has been changed to new domain and ask
user to switch new domain.

Fix Win IO Perf regressions:
- GoogleURLTracker::RequestServerCheck() is not called in headless mode
 (CHROME_HEADLESS=1) nor in Chrome Frame (--chrome-frame).

Fix leaks in TestingProfile::CreateRequestContext(): 52562
- Add TestURLFetcher::set_request_context() do nothing, because TestURLFetcher
 might miss to release core_->request_context_getter_.

Fix GoogleURLTracker observer removal DCHECK: 52608
- call RemoveAll(), instead of calling Remove()s

BUG=48688, 15141, 52477, 52562, 52608
TEST=unit_tests passes

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=56811

[Peter Kasting, 2010-08-19 17:55:10]

LGTM