[Mac] Flip the flag for multi-profiles to on by default.

[Mac] Flip the flag for multi-profiles to on by default.

This also changes ProfileManager::GetProfileInfoCache() to be GetProfileInfo()
and returning the ProfileInfoInterface, making it easier to mock out for testing.
In the few places that require the full ProfileInfoCache, GetMutableProfileInfo()
was added.

Because a handful of Mac unittests make calls into g_browser_process for the
ProfileManager, BrowserTestHelper was expanded to set that up with a
TestingProfile and a FakeProfileInfo so that tests continue to pass.

BUG=60105
TEST=Multi-profiles is on by default.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=97049

[Robert Sesek, 2011-08-15 21:08:11]

For after http://codereview.chromium.org/7647002/ lands.

[sail, 2011-08-15 21:11:40]

LGTM

[Robert Sesek, 2011-08-16 16:53:10]

sail: PTAL
mirandac: Changes done as we've discussed

+mark: BrowserTestHelper. You reviewed changes to it for shess & jrg. I wavered
between allays SetUpProfileManager() or making specific tests do it.

[Mark Mentovai, 2011-08-16 18:08:42]

LGTM. I only reviewed browser_test_helper.{cc,h} as requested.

[Miranda Callahan, 2011-08-16 19:18:31]

On 2011/08/16 18:08:42, Mark Mentovai wrote:
> LGTM. I only reviewed browser_test_helper.{cc,h} as requested.

LGTM!

[sail, 2011-08-16 20:17:33]

LGTM!

http://codereview.chromium.org/7648037/diff/6001/chrome/browser/ui/webui/ntp/...
File chrome/browser/ui/webui/ntp/new_tab_sync_setup_handler.cc (right):

http://codereview.chromium.org/7648037/diff/6001/chrome/browser/ui/webui/ntp/...
chrome/browser/ui/webui/ntp/new_tab_sync_setup_handler.cc:145:
g_browser_process->profile_manager()->GetMutableProfileInfo();
This doesn't have to be mutable if we move more of the ProfileInfoCache
interface to the parent class. We can do this later though.