Use username_hash instead of email as directory name

Previously, email was used as directory name to save user's
custom wallpaper. It is not safe as email may contain special
characters.

After this CL, username_hash will be used as directory name.
And previously saved custom wallpaper will be migrated to new
directory among user login.


BUG=287020

Review URL: https://codereview.chromium.org/23480087

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226140 0039d316-1c4b-4281-b951-d872f2087c98
cros: Remove SwapJank64vs32Parrot experiment

Based on the data from M30 we should be able to switch from 32-bit to 64-bit
builds without hurting the user experience.

BUG=256360
TEST=compiles

Review URL: https://codereview.chromium.org/23514042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226141 0039d316-1c4b-4281-b951-d872f2087c98
Remove accessibility-developer-tools from DEPS

To be submitted after https://codereview.chromium.org/23830003/

BUG=

Review URL: https://codereview.chromium.org/23548013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226142 0039d316-1c4b-4281-b951-d872f2087c98
Update .DEPS.git

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226143 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226142
SVN changes up to revision 226143