Fix Files app popping up after opening the lid with a sd/usb device in.

This patch fixes a race between the resuming and mounting events causing failures in detecting remounting.
Since we may get the resuming event after mounting, we have to flip the remounting flag during suspending.
If we do so, then once the lid is open, we can detect that we are resuming immediately.

TEST=Tested manually on Butterfly.
BUG=311901

Review URL: https://codereview.chromium.org/77463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236208 0039d316-1c4b-4281-b951-d872f2087c98
Added flag that forces first-run UI to show every login.

Flag name is force-first-run-ui.

BUG=none

Review URL: https://codereview.chromium.org/77483002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236209 0039d316-1c4b-4281-b951-d872f2087c98
Cleanup: Fix a typo in string_split.h.

Review URL: https://codereview.chromium.org/77553002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236210 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236209
SVN changes up to revision 236210