Update depot_tools to latest revision.

BUG=chromium:1006774
TEST=NONE

Change-Id: I60cdf9d5cda54b0051ae225267f4b7eea55efc80
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/manifest/+/1819873
Commit-Queue: Min Chen <minch@chromium.org>
Tested-by: Min Chen <minch@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>

full.xml

@@ -431,7 +431,7 @@ Your sources have been sync'd successfully.
     -->
   <project path="chromium/tools/depot_tools"
            name="chromium/tools/depot_tools"
-           revision="84d26ae3c93d2f359972788366805f5d23996441"
+           revision="3841eaa164c2f34c8ea969d462a3151b10151780"
            remote="chromium"
            groups="minilayout,firmware,buildtools,labtools" />
   <project path="src/chromium/src/buildtools"