Roll src/third_party/depot_tools/ 31e7d56c2..81b26429c (6 commits)

https://chromium.googlesource.com/chromium/tools/depot_tools.git/+log/31e7d56c28f1..81b26429c8f6

$ git log 31e7d56c2..81b26429c --date=short --no-merges --format='%ad %ae %s'
2018-04-02 bpastene depot_tools: Kick the recipe roller.
2018-04-02 agable Revert "Remove Rietveld support from presubmit"
2018-04-02 ehmaldonado bot_update: Don't patch if gerrit_repo or gerrit_ref are empty/None.
2018-04-02 agable Disallow TBRs to OWNERS files
2018-04-02 agable git-cl-try: document auth_config for buildbucket
2018-04-02 agable Remove Rietveld support from presubmit

Created with:
  roll-dep src/third_party/depot_tools
BUG=chromium:828154,chromium:770408,chromium:643346,chromium:688115,chromium:770408


The AutoRoll server is located here: https://depot-tools-chromium-roll.skia.org

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

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=agable@chromium.org

Change-Id: I830e86112dda7d11bdca0537ab8879e1a8d745b2
Reviewed-on: https://chromium-review.googlesource.com/991085
Commit-Queue: depot-tools-chromium-autoroll <depot-tools-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Reviewed-by: depot-tools-chromium-autoroll <depot-tools-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#547578}

DEPS

@@ -433,7 +433,7 @@ deps = {
   },
 
   'src/third_party/depot_tools':
-    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '31e7d56c28f1e98b7b4954469233e231e9505467',
+    Var('chromium_git') + '/chromium/tools/depot_tools.git' + '@' + '81b26429c8f61bb4ae22edf4c7de0febbdf47467',
 
   'src/third_party/devtools-node-modules':
     Var('chromium_git') + '/external/github.com/ChromeDevTools/devtools-node-modules' + '@' + Var('devtools_node_modules_revision'),