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,
+      ready: function() {
+        if (this.src) {

[ganetsky1, 2013/12/17 20:57:32]

You might want a srcChanged watcher

[raymes, 2013/12/18 04:46:57]

Done.

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

[ganetsky1, 2013/12/17 20:57:32]

dpi = mql.matches ? 'hi' : 'low';

[raymes, 2013/12/18 04:46:57]

Done.

+              dpi = 'hi';
+            else
+              dpi = 'low';
+          }
+          this.$.icon.style.backgroundImage = 
+              'url(elements/viewer-button/img/' + dpi + 'DPI/' + this.src + ')';
+        }
+        if (this.latchable)
+          this.className += ' latchable';

[ganetsky1, 2013/12/17 20:57:32]

You probably want a latchableChanged watcher instead of doing this. I also
prefer this.classList.add('latchable') and this.classList.remove('latchable')

[raymes, 2013/12/18 04:46:57]

Done.

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