Rerun compare-chromium-versions in all PRs after a chromium major ver…

…sion update on their target branch

.github/workflows/rerun-compare-chromium-versions.yml

@@ -0,0 +1,47 @@
+name: Rerun Compare Chromium versions
+
+on:
+  pull_request:
+    branches:
+      - master
+      - '[0-9]+.[0-9]+.x'
+    paths:
+      - package.json
+    types:
+      - closed
+
+jobs:
+  rerun-compare-chromium-versions:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    env:
+      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      PR_SHA: ${{ github.event.pull_request.head.sha }}
+      TARGET_SHA: ${{ github.event.pull_request.base.sha }}
+    steps:
+      - run: |
+          shopt -s inherit_errexit
+          set -eEo pipefail
+
+          chromium_ver() { curl -fsS "https://raw.githubusercontent.com/${GITHUB_REPOSITORY:?}/${1:?}/package.json"|jq -r .config.projects.chrome.tag; }
+
+          pr_ver="$(chromium_ver "${PR_SHA:?}")"
+          target_ver="$(chromium_ver "${TARGET_SHA:?}")"
+
+          echo "::notice::PR branch: ${pr_ver:?}, target branch: ${target_ver:?}"
+
+          if [[ "${pr_ver%%.*}" != "${target_ver%%.*}" ]]; then
+              while read -r pr_number head_sha; do
+                  run_id="$(gh api "/repos/$GITHUB_REPOSITORY/actions/workflows/compare-chromium-versions.yml/runs?head_sha=${head_sha:?}" -q '.workflow_runs[0].id')"
+                  pr_url="https://github.com/brave/brave-core/pull/${pr_number:?}"
+                  if [[ "$run_id" ]]; then
+                      echo "Rerunning $run_id for $pr_url"
+                      gh -R "$GITHUB_REPOSITORY" run rerun "$run_id"
+                  else
+                      echo "No run found for $pr_url"
+                  fi
+                  sleep 1
+              done < <(gh -R "$GITHUB_REPOSITORY" pr list --limit 1000 --state open --base "$GITHUB_BASE_REF" --json number,headRefOid -q '.[]|"\(.number)\t\(.headRefOid)"')
+          else
+              echo "Chromium major versions match, nothing to do"
+          fi