MD History: Add responsive layout which hides the sidebar in thin windows

chrome/browser/resources/md_history/app.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-pages/iron-pages.html">
 <link rel="import" href="chrome://history/grouped_list.html">
 <link rel="import" href="chrome://history/history_list.html">
 <link rel="import" href="chrome://history/history_toolbar.html">
 <link rel="import" href="chrome://history/synced_device_manager.html">
 <link rel="import" href="chrome://history/side_bar.html">
 <link rel="import" href="chrome://history/shared_style.html">
 <link rel="stylesheet" href="chrome://resources/css/md_colors.css">
 
 <dom-module id="history-app">
   <!-- TODO(calamity): work around this deprecated import style -->
   <template>
     <style no-process>
       history-toolbar {
         background: var(--md-toolbar-color);
       }
     </style>
     <style include="shared-style">
       :host {
         display: block;
         height: 100%;
-        min-width: 800px;
         overflow: hidden;
       }
 
       /* Sizing this with flex causes slow load performance, see
          crbug.com/618153. */
       #main-container {
         height: calc(100% - var(--toolbar-height));
       }
 
       :host([grouped_]) #main-container {
         height: calc(100% - var(--toolbar-grouped-height));
       }
 
       #content,
       #content > * {
         height: 100%;
       }
-
-      #history-side-bar {
-        float: left;
-      }
     </style>
     <history-toolbar id="toolbar"
         spinner-active="[[shouldShowSpinner_(queryState_.querying,
                                              queryState_.incremental,
                                              queryState_.searchTerm)]]"
         is-grouped-mode="{{grouped_}}"
         grouped-range="{{queryState_.range}}"
         search-term="{{queryState_.searchTerm}}"
         query-start-time="[[queryState_.info.queryStartTime]]"
         query-end-time="[[queryState_.info.queryEndTime]]">
     </history-toolbar>
 
     <div id="main-container">
-      <history-side-bar id="history-side-bar" selected-page="{{selectedPage_}}">
-      </history-side-bar>
       <iron-pages id="content" attr-for-selected="id"
           selected="[[getSelectedPage(selectedPage_, queryState_.range)]]">
         <history-list id="history-list" querying="[[queryState_.querying]]"
             searched-term="[[queryState_.info.term]]"></history-list>
         <template is="dom-if" if="[[grouped_]]">
           <history-grouped-list id="history-grouped-list"
               range="[[queryState_.range]]"
               query-start-time="[[queryState_.info.queryStartTime]]"
               query-end-time="[[queryState_.info.queryEndTime]]"
               searched-term="[[queryState_.info.term]]">
           </history-grouped-list>
         </template>
         <template is="dom-if" if="[[syncedTabsSelected_(selectedPage_)]]">
           <history-synced-device-manager id="history-synced-device-manager"
               session-list="[[queryState_.sessionList]]"
               searched-term=[[queryState_.info.term]]>
           </history-synced-device-manager>
         </template>
       </iron-pages>
     </div>
+
+    <history-side-bar id="side-bar" selected-page="{{selectedPage_}}">
+    </history-side-bar>
   </template>
   <script src="chrome://history/app.js"></script>
 </dom-module>