Create ScreenOrientationListener and make it SDK-dependant.

This CL is adding a ScreenOrientationListener abstract class with one
implementation that is based on the current mechanism used for listening
to screen orientation changes. The other implementation is based on
DisplayListener but this API is only available from API Level 17.

BUG=342714, 346696

Review URL: https://codereview.chromium.org/179783003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255750 0039d316-1c4b-4281-b951-d872f2087c98
Remove --disable-local-accounts flag.

This code is stable for a while now, there's no longer any reason to
be able to quickly turn the feature off.

BUG=chromium:350298

Review URL: https://codereview.chromium.org/189163006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255751 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255751