Add native event testing to chromeos::EventRewriter unit tests.
Most tests (not having state) are converted to a table-driven form,
so that multiple test operations can be done on the same test data.
Additional tests based on X11 native events are done on these cases.
The fallback X11 keycode to keysym mapping is expanded, because the
X server used by some automated tests does not support some of the
keycodes used by ChromeOS top-row special keys.
R=sadrul@chromium.org
Review URL: https://codereview.chromium.org/
270633012
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@272428 0039d316-1c4b-4281-b951-d872f2087c98