Mojo: Support camel cased types in generator

BUG=315193
TEST=None
R=darin@chromium.org, darin

Review URL: https://codereview.chromium.org/60863002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233279 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233279