Merge to XFA: Make checkdeps --resolve-dotdot succeed.

This is just a straight-forward, partial merge. It does not
actually make checkdeps succeed.

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1419373005 .

(cherry picked from commit 79f5a32175293620abe456554e10efb7c3f4e7c6)

Review URL: https://codereview.chromium.org/1409153007 .
diff --git a/DEPS b/DEPS
index 56d303c..bf1e65b 100644
--- a/DEPS
+++ b/DEPS
@@ -34,6 +34,8 @@
 }
 
 include_rules = [
+  # Basic stuff that everyone can use.
+  # Note: public is not here because core cannot depend on public.
   '+testing',
   '+third_party/base',
 ]