Redefine (u)int{8,16,32} as (u)int{8,16,32}_t.

We can now do this since we have stdint.h everywhere.

Leave the 64-bit types for now since they require more investigation.

Delete schar, since it's unused in Chromium.

R=brettw@chromium.org
BUG=138542

Review URL: https://codereview.chromium.org/117323010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243143 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243143