Add an OpenDev theme into our Gerrit image

This provides an HTML-only PolyGerrit plugin consistent with our
Gitea theming, generously provided by Paladox (many thanks!).

Since we have to split some roles in the build playbook, also name
the temporary patching role to make the build console a little
easier to read.

Change-Id: I3baf17d04b2dca34fc23dcab91c00544cedf0ca6

docker/gerrit/bazel/Dockerfile

@@ -23,6 +23,8 @@ COPY release.war /var/gerrit/bin/gerrit.war
 RUN mkdir /var/gerrit/plugins && \
   unzip -jo /var/gerrit/bin/gerrit.war WEB-INF/plugins/* -d /var/gerrit/plugins
 
+COPY opendevtheme.html /var/gerrit/plugins/opendevtheme.html
+
 FROM gerrit as gerrit-2
 
 # Only Gerrit 2.14, 2.15, and 2.16 need this COPY

playbooks/zuul/gerrit/opendevtheme.html

@@ -0,0 +1,70 @@
+<!--
+Copyright (C) 2019 The Android Open Source Project
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+<dom-module id="opendev-styles">
+  <script>
+    if (window.Polymer) {
+      Gerrit.install((plugin) => {
+        if (window.localStorage.getItem('dark-theme')) {
+          plugin.registerStyleModule('app-theme', 'opendev-dark-style');
+        } else {
+          plugin.registerStyleModule('app-theme', 'opendev-light-style');
+        }
+        plugin.registerStyleModule('app-theme', 'opendev-common-style');
+      });
+    }
+  </script>
+</dom-module>
+
+<dom-module id="opendev-light-style">
+  <template>
+    <style>
+      html {
+        --header-background: white;
+        --header-text-color: #001133;
+      }
+    </style>
+  </template>
+</dom-module>
+
+<dom-module id="opendev-dark-style">
+  <template>
+    <style>
+      html {
+        --header-background: #3b3d3f;
+        --header-text-color: #e8eaed;
+      }
+    </style>
+  </template>
+</dom-module>
+
+<dom-module id="opendev-common-style">
+  <template>
+    <style>
+      html {
+        --header-title-content: "opendev";
+        --header-icon: url("https://opendev.org/img/opendev-sm.png");
+        --header-icon-size: 1.2em;
+
+        --border-width: 0 0 3px 0;
+        --border-style: solid;
+        --box-shadow: 0 3px 3px 2px rgba(0,0,0,0.075), 0 0 2px rgba(0,0,0,0.2);
+        --header-border-bottom: 4px solid;
+        --header-border-image: linear-gradient(to right, #ed1944 15%, #ed1944 15%, #ed1944 85%, #ed1944 85%) 1;
+      }
+    </style>
+  </template>
+</dom-module>

playbooks/zuul/gerrit/run.yaml

@@ -1,6 +1,7 @@
 - hosts: all
   tasks:
-    - shell: |
+    - name: Patch Gerrit's webapp routes to not shadow x/
+      shell: |
         cd /home/zuul/src/gerrit.googlesource.com/gerrit
         # Disable the x/ redirection since we have x/ projects
         sed -i -e 's|"/x/\*"\,$|//"/x/*",|g' java/com/google/gerrit/httpd/raw/StaticModule.java
@@ -9,6 +10,16 @@
   roles:
     - role: bazelisk-build
       zuul_work_dir: /home/zuul/src/gerrit.googlesource.com/gerrit
+
+- hosts: all
+  tasks:
+    - name: Install OpenDev theme plugin
+      copy:
+        src: opendevtheme.html
+        dest: /home/zuul/src/gerrit.googlesource.com/gerrit/opendevtheme.html
+
+- hosts: all
+  roles:
     - build-docker-image
 
 - hosts: localhost