Adds a unittest for the inline autocompletion in Omnibox.

This test checks if the OmniboxEditModel updates the inline autocomplete text in the OmniboxView.

BUG=310407
TEST=Added AutocompleteEditTest.InlineAutocompleteText in unit_tests.

Review URL: https://codereview.chromium.org/97503003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239438 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239438