Remove all things guava.

This removes the last files regarding guava since
http://crbug.com/380688 has now been addressed.

TBR=darin@chromium.org
BUG=412673

Review URL: https://codereview.chromium.org/602203003

Cr-Commit-Position: refs/heads/master@{#296796}

third_party/guava/OWNERS

-nyquist@chromium.org
-yfriedman@chromium.org

third_party/guava/README.chromium

-Name: Guava: Google Core Libraries for Java 1.6+
-Short Name: guava-libraries
-URL: https://code.google.com/p/guava-libraries/
-Version: NONE
-License: Apache 2.0
-License File: COPYING
-Security Critical: no
-
-Description:
-The Guava project contains several of Google's core libraries.
-
-This file and the COPYING license file are currently just a placeholders,
-as guava was removed in: https://codereview.chromium.org/574103002/.
-Because DEPS are not automatically removed on all bots, this file needs to stay
-around until they do, to make the android_aosp bot happy, since it has a
-requirement for license information for all directories in third_party. The
-current COPYING file is a copy of the one from the guava repository.
-See http://crbug.com/380688 for details.
-TODO(nyquist): Remove this file when http://crbug.com/380688 has been fixed.
-
-Local Modifications:
-None.