Create an empty Polymer element called gr-image-diff-tool

Change-Id: I8a0bd5ab6b84777e75912a8b42f2798c4da1d4cb

.gitignore

diff --git a/.gitignore b/.gitignore
index b321869..d528a68 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,4 +9,5 @@
 dist
 fonts
 .tmp
-.vscode
\ No newline at end of file
+.vscode
+.DS_Store
\ No newline at end of file

gr-image-diff-tool/gr-image-diff-tool.html

diff --git a/gr-image-diff-tool/gr-image-diff-tool.html b/gr-image-diff-tool/gr-image-diff-tool.html
new file mode 100644
index 0000000..eb49f60
--- /dev/null
+++ b/gr-image-diff-tool/gr-image-diff-tool.html
@@ -0,0 +1,23 @@
+<!--
+Copyright (C) 2018 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="gr-image-diff-tool">
+  <template>
+    <style>
+    </style>
+  </template>
+  <script src="gr-image-diff-tool.js"></script>
+</dom-module>
\ No newline at end of file

gr-image-diff-tool/gr-image-diff-tool.js

diff --git a/gr-image-diff-tool/gr-image-diff-tool.js b/gr-image-diff-tool/gr-image-diff-tool.js
new file mode 100644
index 0000000..19769a7
--- /dev/null
+++ b/gr-image-diff-tool/gr-image-diff-tool.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2018 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.
+(function() {
+  'use strict';
+
+  Polymer({
+    is: 'gr-image-diff-tool',
+    properties: {
+      hi: String,
+    },
+  });
+})();
\ No newline at end of file

plugin.html

diff --git a/plugin.html b/plugin.html
index b7066ee..b219f42 100644
--- a/plugin.html
+++ b/plugin.html
@@ -13,11 +13,12 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 -->
+<link rel="import" href="./gr-image-diff-tool/gr-image-diff-tool.html">
 
 <dom-module id="image-diff">
   <script>
     Gerrit.install(plugin => {
-      // TODO: register a component.
+      plugin.registerCustomComponent('image-diff', 'gr-image-diff-tool');
     });
   </script>
 </dom-module>
\ No newline at end of file