libcc/src/third_party/crashpad/README.chromium will have a line Revision: with a checksum
Clone Google's crashpad (https://chromium.googlesource.com/crashpad/crashpad)
git clone https://chromium.googlesource.com/crashpad/crashpadCheck out the branch with the revision checksum:
git checkout <revision checksum>Add electron's crashpad fork as a remote
git remote add electron https://github.com/electron/crashpadCheck out a new branch for the update
git checkout -b electron-crashpad-vA.B.C.DA.B.C.D is the Chromium version found in libcc/VERSION
  and will be something like 62.0.3202.94Make a checklist of the Electron patches that need to be applied
  with git log --oneline
For each patch:
In electron-crashpad-vA.B.C.D, cherry-pick the patch's checksum
git cherry-pick <checksum>Make sure it builds then add, commit, and push work to electron's crashpad fork
git push electron electron-crashpad-vA.B.C.Dcd vendor/crashpadgit fetchgit checkout electron-crashpad-v62.0.3202.94script/update.pyscript/build.py -c D --target=crashpad_clientscript/build.py -c D --target=crashpad_handlergit add vendor/crashpadgit push origin upgrade-to-chromium-62