importer: Cleanup the names of files and classes under ui/cocoa/importer directory.

- Match the names of the files with the current pattern used in the ui/gtk/importer directory.

BUG=None
TEST=existing unit_tests

Review URL: http://codereview.chromium.org/6628039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@77073 0039d316-1c4b-4281-b951-d872f2087c98
12 files changed