Fix issue with doclava download when building varying revisions

Fix issue with doclava download when building varying revisions

If the expanded directory does not exist, delete the tarball
otherwise if the tarball exists and the SHA1 hash matches,
download_from_google_storage will not download and
extract, and any tools depending on the expanded directory will fail.

[pauljensen, 2016-04-19 16:49:56]

pauljensen@chromium.org changed reviewers:
+ agrieve@chromium.org

[pauljensen, 2016-04-19 16:49:57]

Andrew, PTAL. Thank you!

[agrieve, 2016-04-19 17:06:07]

On 2016/04/19 16:49:57, pauljensen wrote:
> Andrew, PTAL. Thank you!

lgtm

[agrieve, 2016-04-19 17:08:00]

On 2016/04/19 17:06:07, agrieve wrote:
> On 2016/04/19 16:49:57, pauljensen wrote:
> > Andrew, PTAL. Thank you!
> 
> lgtm

Actually, not lgtm. I think probably the fix should go in
download_from_google_storage:
https://code.google.com/p/chromium/codesearch#chromium/tools/depot_tools/down...

--extract isn't used much, and this will likely bite the next person that tries
to use it as well.

[pauljensen, 2016-04-19 17:35:56]

On 2016/04/19 17:08:00, agrieve wrote:
> On 2016/04/19 17:06:07, agrieve wrote:
> > On 2016/04/19 16:49:57, pauljensen wrote:
> > > Andrew, PTAL. Thank you!
> > 
> > lgtm
> 
> Actually, not lgtm. I think probably the fix should go in
> download_from_google_storage:
>
https://code.google.com/p/chromium/codesearch#chromium/tools/depot_tools/down...
> 
> --extract isn't used much, and this will likely bite the next person that
tries
> to use it as well.

I started https://codereview.chromium.org/1904483002