Adding new profile accessing functions for primary and active users. This is a first step towards getting rid of GetDefaultProfile.

The removal will be in several steps:
1. Add new functions which describe what they actually get.
2. Have a fixit for all code which looks at all invocations, getting rid of calls what is possible.
3. Remove GetDefaultProfile
4. (Post M33:) Architectural changes to remove the UserManager and / or change the Profile usage into a Browser context user, "somewhere in ash".

BUG=322682
TEST=none
R=dpolukhin@chromium.org, oshima@chromium.org, rlp@chromium.org

Review URL: https://codereview.chromium.org/98783008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239573 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239573
Revert/Fix "Disable PnaclHeaderTest.TestHasPnaclHeader."

This reverts r236737.

The test was failing consistently because of a DCHECK added
in 236651, which was then reverted in 236693, but re-applied
at 236805 after this test was disabled. The issue is that
this test uses EmbeddedTestServer in a way that violated the
DCHECK (http://crbug.com/321422). We have to wait till after
SetUp to start the server now (perhaps the example usage
comments in embedded_test_server.h should no longer recommend
calling InitializeAndWaitUntilReady() in SetUp?).

Also, the dtor automatically does ShutdownAndWaitUntilComplete,
so no longer need to put that under TearDown().

BUG=315328
R=ncbray@chromium.org, oshima@chromium.org

Review URL: https://codereview.chromium.org/83073010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239575 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239575