Fix minor issues in PPB_TrueTypeFont_Dev implementation.

1) PepperTrueTypeFontWin::GetTable needs to match behavior on Mac and Linux,
where we return success and copy 0 bytes if offset is off the end of a table.
2) Remove useless code from the message filter used by PepperTrueTypeFontListHost.

BUG=none

Review URL: https://codereview.chromium.org/27317003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228775 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228775
Add whitelist for extensions that can invoke feedback.

R=xiyuan@chromium.org
BUG=307328

Review URL: https://codereview.chromium.org/27370004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228776 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228776