[MD History] Add routing to the synced devices page.

chrome/browser/resources/md_history/side_bar.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-item/paper-item.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-listbox/paper-listbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-ripple/paper-ripple.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 <link rel="import" href="chrome://history/shared_style.html">
 
 <dom-module id="history-side-bar">
   <template>
@@ skipping 24 matching lines @@
         color: var(--google-blue-500);
         font-weight: 500;
       }
 
       paper-listbox {
         -webkit-user-select: none;
         background-color: transparent;
         color: #5a5a5a;
       }
     </style>
-    <paper-listbox id="overflow-menu" selected="0" on-iron-select="onSelect_"
+    <paper-listbox id="menu" selected="[[routeData.page]]"

[tsergeant, 2016/06/08 03:42:17]

Should this be 2-way bound?

[calamity, 2016/06/14 05:05:50]

Nah.

+        attr-for-selected="path" on-iron-select="onSelect_"
         selectable=".page-item">
-      <paper-item view-id="history-list" class="page-item">
+      <paper-item view-id="history-list" class="page-item" path="">

[tsergeant, 2016/06/08 03:42:18]

This element has a bunch of extra logic to work with the awkwardness around
selectedPage vs route.

You might be able to simplify this logic a bunch by using <a> tags. Then the
flow becomes:

click <a> -> app-route updates -> selected page updates -> sidebar selection
updates.

We would also get the other benefits of <a> tags like being able to middle
click.

[calamity, 2016/06/14 05:05:50]

Done.

         <div>$i18n{historyMenuItem}</div>
         <paper-ripple></paper-ripple>
       </paper-item>
-      <paper-item view-id="history-synced-device-manager" class="page-item">
+      <paper-item view-id="history-synced-device-manager" class="page-item"
+          path="openTabs">
         <div>$i18n{openTabsMenuItem}</div>
         <paper-ripple></paper-ripple>
       </paper-item>
       <div class="separator"></div>
       <paper-item on-tap="onClearBrowsingDataTap_" id="clear-browsing-data">
         <div>$i18n{clearBrowsingData}</div>
         <paper-ripple></paper-ripple>
       </paper-item>
     </paper-listbox>
   </template>
   <script src="chrome://history/side_bar.js"></script>
 </dom-module>