Yeah, they were used for our Google Cloud Print integration and Chrome to Mobile.
It seems like I added the following third_party directories:
apache-mime4j
guava
httpcomponents-client
httpcomponents-core
jarjar

I'll put up a patch to delete them.

I have this CL out for review: https://codereview.chromium.org/2642403002/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b85b9eb8d1d91ccc172f53eec3e277eab60c47ce

commit b85b9eb8d1d91ccc172f53eec3e277eab60c47ce
Author: nyquist <nyquist@chromium.org>
Date: Fri Jan 20 19:20:19 2017

Remove unnecessary third party dependencies

The CL https://codereview.chromium.org/11421224 added several
third party dependencies required for the feature Chrome to Mobile.

As the feature has been removed, this CL deals with removing
the dependencies that the CL added. The action taken for each new
dependency is listed below:

- apache-mime4j: Removed from .gitignore and DEPS.
- guava: Was deleted in https://codereview.chromium.org/602203003,
         but was later added back in
         https://codereview.chromium.org/2041583002. However, as its
         uses are now only related to tests, the 'testonly = true' flag
         has been added to its BUILD.gn file.
- httpcomponents-client: Removed from .gitignore and DEPS.
- httpcomponents-core: Removed from .gitignore and DEPS.
- jarjar: Removed from .gitignore as
          https://codereview.chromium.org/2072873003 only deleted the
          DEPS entry.

BUG= 682983 

Review-Url: https://codereview.chromium.org/2642403002
Cr-Commit-Position: refs/heads/master@{#445123}

[modify] https://crrev.com/b85b9eb8d1d91ccc172f53eec3e277eab60c47ce/.gitignore
[modify] https://crrev.com/b85b9eb8d1d91ccc172f53eec3e277eab60c47ce/DEPS
[modify] https://crrev.com/b85b9eb8d1d91ccc172f53eec3e277eab60c47ce/third_party/guava/BUILD.gn