Add the viewer toolbar to the PDF extension

chrome/browser/resources/pdf/elements/viewer-button/viewer-button.html

+<polymer-element name="viewer-button" attributes="src latchable">
+  <template>
+    <link rel="stylesheet" href="viewer-button.css">
+    <div id="icon"></div>
+  </template>
+  <script>
+    (function() {
+    var dpi = '';
+
+    Polymer('viewer-button', {
+      src: '',
+      latchable: false,
+      srcChanged: function() {

[ganetsky1, 2013/12/18 20:05:05]

fyi you can use oldValue, newValue as arguments here

+        if (this.src) {
+          if (!dpi) {
+            var mql = window.matchMedia('(-webkit-min-device-pixel-ratio: 1.3');
+            dpi = mql.matches ? 'hi' : 'low';
+          }
+          this.$.icon.style.backgroundImage = 
+              'url(elements/viewer-button/img/' + dpi + 'DPI/' + this.src + ')';
+        }

[ganetsky1, 2013/12/18 20:05:05]

You probably want an else branch which unsets this.$.icon.style.backgroundImage.
In other words, respond to someone clearing the src attribute, don't ignore it
as you are doing now.

[raymes, 2013/12/18 23:28:54]

Done.

+      },
+      latchableChanged: function() {

[ganetsky1, 2013/12/18 20:05:05]

fyi, you can use oldValue, newValue as arguments here

+        if (this.latchable)
+          this.classList.add('latchable')
+        else
+          this.classList.remove('latchable')
+      },
+    });
+    })();
+  </script>
+</polymer-element>