IndexedDB: Implement back-end for IDBCursor.continuePrimaryKey()

Plumbing to allow a cursor to be walked on the secondary ordering
(primary key) of the store. (Not exposed to script without
a corresponding Blink change.)

BUG=284830

Review URL: https://codereview.chromium.org/23534040

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235501 0039d316-1c4b-4281-b951-d872f2087c98
Add a full screen virtual keyboard to virtual keyboard root window


BUG=310331
TEST=
1. add keyboard-usability-experiment flag
2. hook up an external screen
3. boot device
expected: a full screen keyboard on one of the screen

Review URL: https://codereview.chromium.org/47873003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235502 0039d316-1c4b-4281-b951-d872f2087c98
[rAc OSX] Remove some unnecessary code for size computations during init.

BUG=none
TEST=none
R=groby@chromium.org

Review URL: https://codereview.chromium.org/61733020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235503 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235503