Retires FakeInputMethod and introduces InputMethodMinimal.

FakeInputMethod is no longer used except for Ozone, and Ozone needs the minimal input feature, at least as a fallback.  Retires FakeInputMethod and introduces InputMethodMinimal.

BUG=312211
TEST=none

Review URL: https://codereview.chromium.org/102643006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238649 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238649