Allow hash migration for unloaded profiles.

This augments the current capacity to seed unloaded profiles to also be able to go through the migration path from the old hashes to the new ones for profiles that have yet to migrate.

This introduces a PrefHashStore version which will begin at 2 (0 being the absence of hashes and 1 being the presence of the old hashes).

R=jwd@chromium.org, robertshield@chromium.org
TBR=sky (chrome_browser_main.cc -- see comment #22)

Review URL: https://codereview.chromium.org/164463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251700 0039d316-1c4b-4281-b951-d872f2087c98
Use subprocess.call instead of os.system in DownloadSDK8.

subprocess.call handles pathnames containing spaces better.

R=scottmg@chromium.org
BUG=343904
TEST=run toolchain.py in a user account name containing a
space, such as "John Smith".

Review URL: https://codereview.chromium.org/168233002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251701 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 251700
SVN changes up to revision 251701