[TOOLS] Add vanilla chromium build (#1200)

fix "Prepare Build Container for vanilla chromium" stage

.github/workflows/build_additional_targets.yaml

@@ -152,6 +152,13 @@ jobs:
           gpg --homedir ./ -d --passphrase "${{ secrets.KEYSTORE_PASSPHRASE }}" --batch cromite.keystore.asc > cromite.keystore
           echo "::endgroup::"
 
+      - name: Prepare Build Container for vanilla chromium
+        shell: bash
+        run: |
+          # set workspace paths
+          PATH=$WORKSPACE/chromium/src/third_party/llvm-build/Release+Asserts/bin:$WORKSPACE/depot_tools/:/usr/local/go/bin:$WORKSPACE/mtool/bin:$PATH
+          cd $WORKSPACE/chromium/src
+
           # checkout chromium commit
           LAST_PATCH=$(git log --all --grep='Fix-chromium-vanilla.patch' --format="%H")
           git checkout $LAST_PATCH