Added toolbar

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

+<polymer-element name="viewer-toolbar">
+  <template>
+    <link rel="stylesheet" href="viewer-toolbar.css">
+    <div id="hover" on-mouseover="{{fadeIn}}" on-mousemove="{{fadeIn}}" on-mouseout="{{fadeOut}}">
+      <div id="toolbar">
+        <content></content>
+      </div>
+    </div>
+  </template>
+  <script>
+    Polymer('viewer-toolbar', {
+      fadingIn: false,
+      ready: function() {
+        this.fadeOut();
+      },
+      fadeIn: function(event, detail, sender) {
+        this.fadingIn = true;
+        this.updateStyle();
+      },
+      fadeOut: function() {
+        this.fadingIn = false;
+        this.updateStyle();          
+      },
+      updateStyle: function() {
+        if (this.fadingIn) {
+          this.style.setProperty("-webkit-transition",
+                                 "opacity 0.4s ease-in-out");
+          this.style.opacity = 1;
+        } else {
+          if (window.getComputedStyle(this).getPropertyValue("opacity") == 1) {
+            this.style.setProperty("-webkit-transition",
+                                   "opacity 0.4s ease-in-out 3s");
+            this.style.opacity = 0;
+          } else {
+            // Let the toolbar finish fading in before fading out.
+            var me = this; 
+            setTimeout(function() { me.updateStyle(); }, 400);
+          }
+        }
+      }
+    });
+  </script>
+</polymer-element>