Use code review in DOM distiller dist repo

Before this CL, this script builds DOM distiller, pushes the compiled
artifacts to the dom-distiller/dist repo, and generates a local commit
for rolling. The local commit needs to be uploaded as a CL.

In order to avoid pushing without reviewing, we want to generate a CL
in the dom-distiller/dist repo instead of directly pushing to it.

When reviewing the CL in the dom-distiller/dist repo, the reviewer
needs to run update_domdistiller_js.sh in validation mode to make sure
the artifacts in the CL are identical to local output.

Bug: None
Change-Id: Ia29c1686106c3516f341e4d826aca69842ac5668
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2304338Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789575}

third_party/dom_distiller_js/update_domdistiller_js.sh

@@ -5,10 +5,13 @@
 # found in the LICENSE file.
 #
 
-# Clones the dom-distiller repo, compiles and extracts its javascript Then
-# copies that js into the Chromium tree.
+# Clones the dom-distiller repo, compiles and extracts its JavaScript. The
+# artifact would be uploaded as a CL in dom-distiller/dist repo, and then
+# generates a rolling commit to be uploaded.
 # This script requires that ant is installed. It takes an optional parameter
-# for which SHA1 to roll to. If left unspecified the script rolls to HEAD.
+# for which SHA1 in dom-distiller repo to roll to. If left unspecified the
+# script rolls to HEAD. The second optional parameter is the Gerrit URL of
+# the CL in dom-distiller/dist repo to be validated.
 
 (
   set -e
@@ -27,11 +30,17 @@
   mkdir $tmpdir
   pushd $tmpdir
 
+  function finish {
+    rm -rf $tmpdir
+  }
+  trap finish EXIT
+
   git clone $repo_host/dom-distiller
   pushd dom-distiller
 
   # The new git SHA1 is HEAD or the first command line parameter.
   [[ -z "$1" ]] && gitsha_target="HEAD" || gitsha_target="$1"
+  gerrit_url="$2"
   new_gitsha=$(git rev-parse --short=10 ${gitsha_target})
   git reset --hard ${new_gitsha}
   git log --oneline ${curr_gitsha}..${new_gitsha} > $changes
@@ -57,8 +66,13 @@
   popd # dom-distiller
 
   git clone $repo_host/dom-distiller/dist $tmpdir/dom-distiller-dist
-  rm -rf $tmpdir/dom-distiller-dist/*
   pushd dom-distiller-dist
+  if [[ -n "$gerrit_url" ]]; then
+    echo "Validating $gerrit_url"
+    git cl patch --force $gerrit_url
+  fi
+  rm -rf $tmpdir/dom-distiller-dist/*
+
   cp -r $tmpdir/dom-distiller/out/package/* .
 
   # Stop rolling python/plugin_pb2.py for protobuf backward compatibility.
@@ -67,10 +81,35 @@
 
   git add .
   if [[ $(git status --short | wc -l) -ne 0 ]]; then
-    git commit -a -m "Package for ${new_gitsha}"
-    git push origin master
+    if [[ -n "$gerrit_url" ]]; then
+      echo "FAIL. The output is different from $gerrit_url."
+      exit 1
+    fi
+    # For Change-Id footer.
+    curl -Lo $(git rev-parse --git-dir)/hooks/commit-msg https://gerrit-review.googlesource.com/tools/hooks/commit-msg
+    chmod +x $(git rev-parse --git-dir)/hooks/commit-msg
+
+    gen_message () {
+      echo "Package for ${new_gitsha}"
+      echo
+      echo "This is generated from:"
+      echo "${repo_host}/dom-distiller/+/${new_gitsha}."
+      echo
+      echo "To validate, run the following command in chromium/src:"
+      echo "third_party/dom_distiller_js/update_domdistiller_js.sh ${new_gitsha} <Gerrit-URL>"
+    }
+
+    message=$tmpdir/message
+    gen_message > $message
+
+    git commit -a -F $message
+    git push origin master:refs/for/master
   else
     # No changes to external repo, but need to check if DEPS refers to same SHA1.
+    if [[ -n "$gerrit_url" ]]; then
+      echo "PASS. The output is the same as $gerrit_url."
+      exit 0
+    fi
     echo "WARNING: There were no changes to the distribution package."
   fi
   new_dist_gitsha=$(git rev-parse HEAD)
@@ -80,7 +119,6 @@
   curr_dist_gitsha=$(grep -e "/chromium\/dom-distiller\/dist.git" $src_path/DEPS | sed -e "s/.*'\([A-Za-z0-9]\{40\}\)'.*/\1/g")
   if [[ "${new_dist_gitsha}" == "${curr_dist_gitsha}" ]]; then
     echo "The roll does not include any changes to the dist package. Exiting."
-    rm -rf $tmpdir
     exit 1
   fi
 
@@ -101,7 +139,6 @@
     cat $bugs
   }
 
-  message=$tmpdir/message
   gen_message > $message
 
   # Run checklicenses.py on the pulled files, but only print the output on
@@ -109,6 +146,4 @@
   $src_path/tools/checklicenses/checklicenses.py third_party/dom_distiller_js > $tmpdir/checklicenses.out || cat $tmpdir/checklicenses.out
 
   git commit -a -F $message
-
-  rm -rf $tmpdir
 )