[Extension DocServer] Update BranchUtility, README

chrome/common/extensions/docs/server2/README

 --------
 Overview
 
 This is a Google App Engine server which serves the documentation for Chrome
 apps and extensions. At time of this writing, the primary URL is:
 http://developer.chrome.com/.
 
 
 ---------------------
 Developing the Server
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      You may also specify --commit=<commitish> when running update_cache.py in
      order to update the cache from a specific commit. This may be a commit ID,
      or a partial commit ID, or a local branch ref, etc. To test local changes,
      you MUST commit them locally and use the local commit to update your cache.
 
   2. Once you have a cache (e.g. FOOCACHE) in the working directory of your
      dev server, visit the URL:
 
        http://localhost:8080/_update_cache/FOOCACHE
 
+     If you see errors about the FOOCACHE file not existing, the server may be
+     looking for the file in the root chromium directory (under src/), even if
+     you launched the server from the server2 directory. Try moving the FOOCACHE
+     file there.
+
      The server should take about a minute to fully populate its Datastore
      from the data in your FOOCACHE file. Now you have a working dev server!
 
 
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 Using Google Cloud Storage content providers with preview.py
 
   1. create a directory "[...]/server2/local_debug/gcs/<bucketname>" for every
      gcs bucket referenced in content_providers.json
 
   2. copy files to the respective local bucket directories. Preview.py has
      no access to the real Google Cloud Storage.
 
 
 --------------------
 Deploying the Server

[Devlin, 2016/08/17 00:44:32]

Ken, do you know if this process is still correct?

 
 You will need to have access to the http://chrome-apps-doc.appspot.com app.
 Contact kalman@chromium.org or rockot@chromium.org to obtain access.

[asargent_no_longer_on_chrome, 2016/08/17 18:16:32]

While you're in here, you could remove kalman@ from this line =)

[Devlin, 2016/08/17 21:11:32]

Done.  I didn't want to volunteer you/lazyboy/catmullings, so I've polyfilled
with "me or another extensions team member".

 
 Once you have access:
 
 1. Increment the version in app.yaml so we can roll back if the update breaks.
 
 2. Run build_server.py. This copies some depenencies from /third_party into the
    server directory so that they get uploaded to App Engine.
 
 3. Run appcfg.py (supplied with the App Engine SDK) to upload the server code:
 
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 consider the case where no new commits are landing in the chrome repository
 but a change was just pushed to one of the GCS providers (like say, the
 chromedocs-multidevice bucker). In this case, you may want to force an update
 of only the content_providers data.
 
   ./update_docs.sh --data-source=content_providers --force
 
 This will safely do the push for you, ensuring that the automated job
 does not collide with your own.