Remove iron-flex-layout from cr-network

ui/webui/resources/cr_elements/network/cr_network_select.html

 <link rel="import" href="chrome://resources/html/polymer.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_expand_button/cr_expand_button.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_network_list.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_network_list_network_item.html">
 <link rel="import" href="chrome://resources/cr_elements/network/cr_onc_types.html">
 
 <dom-module id="cr-network-select">
   <template>
     <style>
       :host {
         display: inline-block;
       }
+
+      #container {
+        display: flex;
+        flex-direction: column;
+      }
+
+      header {
+        display: flex;
+        align-items: center;
+      }
+
+      header cr-network-list-network-item {
+        flex: 1;
+      }

[stevenjb, 2016/08/12 23:20:48]

nit: FWIW I find all of these custom rules much less readable than the layout
classes.

That said, it sounds like there is a non trivial amount of overhead with
including the iron layout style, so for anything inside cr_elements/ it seems
reasonable to not include it.

     </style>
-    <div class="layout vertical">
-      <div class="layout horizontal center">
-        <cr-network-list-network-item class="flex" hidden$="[[!showActive]]"
+    <div id="container">
+      <header>

[stevenjb, 2016/08/12 23:20:47]

nit: I'd rather just use a div here. I don't think there is a clear consensus on
where we should use <header> vs <div>, and since we don't use it anywhere else
in settings, I would prefer not to start here.

+        <cr-network-list-network-item hidden$="[[!showActive]]"
             network-state="[[activeNetworkState]]">
         </cr-network-list-network-item>
         <cr-expand-button toggles hidden$="[[!expandable]]"
             expanded="{{networkListOpened}}">
         </cr-expand-button>
-      </div>
+      </header>
       <cr-network-list opened="[[networkListOpened]]" max-height="[[maxHeight]]"
           networks="[[networkStateList]]" custom-items="[[customItems]]"
           on-selected="onNetworkListItemSelected_" show-buttons=[[showButtons]]>
       </cr-network-list>
     </div>
   </template>
   <script src="cr_network_select.js"></script>
 </dom-module>