Rename Chromoting string resource IDs from IDR_ to IDS_.

This makes the names consistent with other string resources in Chrome,
and is needed for localizing the Android client.

Review URL: https://codereview.chromium.org/140683010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247303 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247303