Add a favicon to the web ui. I went with the one from www.ampproject.org

. (#3238)

Also very slightly simplified the location for webcomponents-lite.js in
  the appengine app.

validator/build.py

@@ -417,10 +417,8 @@ def CreateWebuiAppengineDist(out_dir):
                       f for f in files
                       if not os.path.isdir(os.path.join(d, f)) and
                       os.path.splitext(f)[1] != '.html'])
-  webcomponents_out = os.path.join(out_dir, 'webcomponents-lite')
-  os.mkdir(webcomponents_out)
   shutil.copyfile('node_modules/webcomponents-lite/webcomponents-lite.js',
-                  os.path.join(webcomponents_out, 'webcomponents-lite.js'))
+                  os.path.join(webui_out, 'webcomponents-lite.js'))
   logging.info('... success')
 
 

validator/index.js

@@ -410,6 +410,16 @@ function serve(port, validatorScript) {
           return;
         }
         //
+        // Handle '/amp_favicon.png'
+        //
+        if (request.url == '/amp_favicon.png') {
+          const contents = fs.readFileSync(
+              path.join(__dirname, 'webui/amp_favicon.png'), 'binary');
+          response.writeHead(200, {'Content-Type': 'image/png'});
+          response.end(contents, 'binary');
+          return;
+        }
+        //
         // Handle fetch?, a request to fetch an arbitrary doc from the
         // internet. It presents the results as JSON.
         //

validator/webui/app.yaml

@@ -19,5 +19,9 @@ handlers:
   upload: polymer/.*\.html$
 
 - url: /webcomponents-lite.js$
-  static_files: webcomponents-lite/webcomponents-lite.js
-  upload: webcomponents-lite/webcomponents-lite\.js$
+  static_files: webcomponents-lite.js
+  upload: webcomponents-lite\.js$
+
+- url: /amp_favicon.png$
+  static_files: amp_favicon.png
+  upload: amp_favicon\.png$

validator/webui/index.html

@@ -18,6 +18,7 @@
   <meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1, user-scalable=yes">
   <title>The AMP Validator</title>
   <meta charset="utf-8"/>
+  <link rel="shortcut icon" href="/amp_favicon.png">
   <script src="webcomponents-lite.js"></script>
   <link rel="import" href="/pm/iron-collapse/iron-collapse.html">
   <link rel="import" href="/pm/iron-flex-layout/iron-flex-layout.html">