Roll src/third_party/devtools-frontend/src a0840e9a2f6a..9b547ca554d8 (3 commits)

https://chromium.googlesource.com/devtools/devtools-frontend.git/+log/a0840e9a2f6a..9b547ca554d8

git log a0840e9a2f6a..9b547ca554d8 --date=short --first-parent --format='%ad %ae %s'
2020-01-15 devtools-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com Update DevTools DEPS.
2020-01-15 tmathmeyer@chromium.org Rolled MediaTable into EventDisplayTable
2020-01-14 anubmat@microsoft.com DevTools: Fix a zooming issue in timeline panel details view

Created with:
  gclient setdep -r src/third_party/devtools-frontend/src@9b547ca554d8

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/devtools-frontend-chromium
Please CC devtools-waterfall-sheriff-onduty@grotations.appspotmail.com 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: chromium:794255,chromium:963183
Tbr: devtools-waterfall-sheriff-onduty@grotations.appspotmail.com
Change-Id: Ie045c54d34fb92990d3804a26cf7dd1493bacf73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2001567Reviewed-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@{#731861}

DEPS

@@ -252,7 +252,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling devtools-frontend
   # and whatever else without interference from each other.
-  'devtools_frontend_revision': 'a0840e9a2f6a2c7c2f5e423350ca7657df07b14b',
+  'devtools_frontend_revision': '9b547ca554d8858398fd454f652d0a7e6b07af2b',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling libprotobuf-mutator
   # and whatever else without interference from each other.