Re-connect search on MD downloads

chrome/browser/resources/md_downloads/toolbar.html

 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icons/iron-icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.html">
 <link rel="import" href="chrome://resources/cr_elements/v1_0/cr_button/cr_button.html">
 <link rel="import" href="chrome://resources/cr_elements/v1_0/cr_input/cr_input.html">
+<link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 
 <dom-module id="downloads-toolbar">
   <template>
     <div id="title">
       <h1 i18n-content="title"></h1>
     </div>
     <div id="actions">
       <cr-button id="clear-all" i18n-content="clearAll"
-          on-click="onClearAllClick_"
-          hidden$="[[!canClearAll]]"></cr-button>
+          on-click="onClearAllClick_"></cr-button>

[michaelpg, 2015/07/30 02:48:16]

suggestion: hidden="[[!canClearAll(searchTerm, downloadsShowing)]]"

       <cr-button id="open-downloads-folder" i18n-content="openDownloadsFolder"
           on-click="onOpenDownloadsFolderClick_"></cr-button>
     </div>
     <div id="search">
       <paper-icon-button icon="search" id="search-button"
           on-click="toggleShowingSearch_"></paper-icon-button>
       <cr-input id="search-term" i18n-values="label:search"
           hidden$="[[!showingSearch_]]" no-label-float></cr-input>

[michaelpg, 2015/07/30 02:48:16]

with the above suggestion: value="{{searchTerm}}"

       <paper-icon-button icon="clear" id="clear-search"
           on-click="toggleShowingSearch_"
           hidden$="[[!showingSearch_]]"></paper-icon-button>
     </div>
   </template>
   <link rel="import" type="css" href="chrome://downloads/shared_style.css">
   <link rel="import" type="css" href="chrome://downloads/toolbar.css">
   <script src="chrome://downloads/toolbar.js"></script>
 </dom-module>