Mojo: Add hooks for dispatchers to serialize themselves.

Reland (committed r253869, reverted r253876; win64 breakage).

R=yzshen@chromium.org

Review URL: https://codereview.chromium.org/182163002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253947 0039d316-1c4b-4281-b951-d872f2087c98
Extend scope of the accessibility watchlist to cover braille, liblouis and chromevox changes.

TEST=watchlist.py on some existing files including the new patterns.

R=dmazzoni@chromium.org
BUG=none

Review URL: https://codereview.chromium.org/183703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253948 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253948