Add information for checking in large files in adding_to_third_party.md

docs/adding_to_third_party.md

 # Adding third_party Libraries
 
 [TOC]
 
 Using third party code can save time and is consistent with our values - no need
 to reinvent the wheel! We put all code that isn't written by Chromium developers
 into src/third_party (even if you end up modifying just a few functions). We do
 this to make it easy to track license compliance, security patches, and supply
 the right credit and attributions. It also makes it a lot easier for other
 projects that embed our code to track what is Chromium licensed and what is
@@ skipping 85 matching lines @@
 developers that don't need your code. When all platforms really do need the
 code, checking it in to src/third_party allows some slight improvements over
 DEPS._
 
 As for specifying the path where the library is fetched, a path like
 `src/third_party/<project_name>/src` is highly recommended so that you can put
 the file like OWNERS or README.chromium at `third_party/<project_name>`. If you
 have a wrong path in DEPS and want to change the path of the existing library in
 DEPS, please ask the infrastructure team before committing the change.
 
+### Checking in large files
+_Accessible to Googlers only. Non-Googlers can email one of the people in
+third_party/OWNERS for help._
+
+See [Moving large files to Google Storage](https://sites.google.com/a/google.com/chrome-infrastructure/platform/git-conversion/moving-large-files-to-google-storage?pli=1)

[agrieve, 2016/12/16 20:29:00]

nit: wrap internal link in a shortener via https://goo.gl/

[F, 2016/12/16 21:28:42]

Done.

+
 ## Setting up ignore
 
 If your code is synced via DEPS, you should add the new directory to Chromium's
 `.gitignore`. This is necessary because Chromium's main git repository already
 contains
 [src/third_party](http://src.chromium.org/viewvc/chrome/trunk/src/third_party/)
 and the project synced via DEPS is nested inside of it and its files regarded as
 untracked. That is, anyone running `git status` from `src/` would see a clutter.
 Your project's files are tracked by your repository, not Chromium's, so make
 sure the directory is listed in Chromium's `.gitignore`.
@@ skipping 69 matching lines @@
 
 * Missing license file
     * Make sure that the license file is present. It should be called 'LICENSE',
       or otherwise README.chromium file must point to it explicitly.
 * The following files contain a third-party license but are not in a listed
   third-party directory...
     * Check if it's a false positive (e.g. 'copyright' word used in a string
       literal), if so, update
       [src/tools/copyright_scanner/third_party_files_whitelist.txt](https://code.google.com/p/chromium/codesearch#chromium/src/tools/copyright_scanner/third_party_files_whitelist.txt)
       file. Otherwise, please move the code into third_party.