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() {
+        if (this.src) {
+          if (!dpi) {
+            var mql = window.matchMedia('(-webkit-min-device-pixel-ratio: 1.3');
+            dpi = mql.matches ? 'hi' : 'low';
+          }

[ganetsky1, 2014/01/03 18:14:39]

You may want to consider moving this out to ready: function() {...}

[raymes, 2014/01/06 00:22:45]

Done.

+          this.$.icon.style.backgroundImage =
+              'url(elements/viewer-button/img/' + dpi + 'DPI/' + this.src + ')';
+        } else {
+          this.$.icon.style.backgroundImage = '';
+        }
+      },
+      latchableChanged: function() {
+        if (this.latchable)
+          this.classList.add('latchable')
+        else
+          this.classList.remove('latchable')

[ganetsky1, 2014/01/03 18:14:39]

Semicolon?

Also, maybe you want to use { } around each branch. I don't know the style
guidelines here.

[raymes, 2014/01/06 00:22:45]

Added the semicolons. The braces aren't required for single-line if's IIUC

+      },
+    });
+    })();
+  </script>
+</polymer-element>