Roll src/third_party/depot_tools 7f9e1a2dc019..6865d13248b3 (3 commits)

https://chromium.googlesource.com/chromium/tools/depot_tools.git/+log/7f9e1a2dc019..6865d13248b3

git log 7f9e1a2dc019..6865d13248b3 --date=short --first-parent --format='%ad %ae %s'
2019-12-10 agable@chromium.org Update git-drover to use branch CQ
2019-12-10 recipe-mega-autoroller@chops-service-accounts.iam.gserviceaccount.com Roll recipe dependencies (trivial).
2019-12-10 iannucci@chromium.org Roll python 2 and 3 to versions matching the fleet.

Created with:
  gclient setdep -r src/third_party/depot_tools@6865d13248b3

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/depot-tools-chromium-autoroll
Please CC agable@chromium.org on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

Bug: None
Tbr: agable@chromium.org
Change-Id: I0ec868c0fafe146b21b6adf7b9009b74c3895408
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1960996Reviewed-by: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#723605}

DEPS

@@ -886,7 +886,7 @@ deps = {
   },
 
   'src/third_party/depot_tools':
-    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '7f9e1a2dc0194ba6cb2a5c1bf4cfa730744b0d3e',
+    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '6865d13248b39c0f70e124e7cfe8fd7097f1652a',
 
   'src/third_party/devtools-frontend/src':
     Var('chromium_git') + '/devtools/devtools-frontend' + '@' + Var('devtools_frontend_revision'),