default.xml: Add lint libraries to project.

We can now use "cros lint" here.

BUG=None
TEST=Local sync.

Change-Id: Ib53e945c03246e909c1015fbdc7970da81c3858c
Reviewed-on: https://chromium-review.googlesource.com/308060
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Matthew Sartori <msartori@chromium.org>
diff --git a/default.xml b/default.xml
index 9101401..67f9e1c 100644
--- a/default.xml
+++ b/default.xml
@@ -13,4 +13,9 @@
 
   <project path="chromite" name="chromiumos/chromite" />
   <project path="chromite/config" name="chromiumos/chromite/abuildbot_config" />
+
+  <!-- To get requirements for cros lint -->
+  <project path="chromium/tools/depot_tools"
+           name="chromium/tools/depot_tools"
+           revision="b6795643ec0305ba2ff862fcd0f450756aa5e58c" />
 </manifest>