Add gclient hook to download SDK extras on bots.

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index 6fe932dbcc62b48cafdde3aee18b9c2cff508d8d..a9e04f42ccad066c1bcd45d5b17dc549a5afe7c9 100644
--- a/DEPS
+++ b/DEPS
@@ -550,6 +550,15 @@ hooks = [
     ],
   },
   {
+    # This downloads SDK extras and puts them in the
+    # third_party/android_tools/sdk/extras directory on the bots. Developers
+    # need to manually install these packages and accept the ToS.
+    'name': 'sdkextras',
+    'pattern': '.',
+    'action': ['python', 'src/build/download_sdk_extras.py',

[nyquist, 2014/11/25 20:08:26]

Would this overwrite what's already in the checkout in sdk/extras on the build
after this lands?

[navabi, 2014/11/25 20:40:49]

Yes it will. Because it uses rsync, so it will sync the local directory to what
is in the google storage bucket.

+               'google_google_play_services_21.0.0'],

[nyquist, 2014/11/26 04:34:51]

does this directory structure have to be flattened?
could we instead checkout everything here under each branch somehow?

so you'd have one directory for 2171, and one for master, etc.?
and then the folder structure within there would be correct?

if you do that you don't have to be worried about keeping everything in the
external repo.

[navabi, 2014/11/26 18:52:35]

Sorry Tommy, but I don't know what you mean.

The directory structure does not and is not flattened. The contents of
google_google_play_services_21.0.0 is google/google_play_services/<otherstuff>.
Maybe I am misunderstanding you, but flattened to me means all the contents is
one directory.

I'm not sure what you mean by one directory for 2171 and one for master.

And when you say "external repo", are you referring to the google storage bucket
as a repo?

[nyquist, 2014/11/26 19:15:51]

Sorry. Okay; my thought was keeping a folder in the bucket named 'master' and
'2171'. In that folder you would have the full extras directory, including
google/google_play_services/<otherstuff>.

However, thinking about it, to ensure we have consistent builds, what you are
proposing might be better. At that point you also definitely do not want to
delete anything using rsync.

One thing comes up then though; if you 'roll' google play services to some new
version after 21, how would you clean up old files in
third_party/android_tools/sdk/extras/google/google_play_services?
There might be files that are removed in the newer version, that with this
approach might stick around.

+  },
+  {
     # Downloads the Debian Wheezy sysroot to chrome/installer/linux if needed.
     # This sysroot updates at about the same rate that the chrome build deps
     # change. This script is a no-op except for linux users who are doing