MD downloads: implement real warning icon

chrome/browser/resources/md_downloads/item.html

 <link rel="import" href="chrome://resources/html/action_link.html">
 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/load_time_data.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/polymer/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-material/paper-material.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-progress/paper-progress.html">
 <link rel="import" href="chrome://resources/cr_elements/v1_0/cr_button/cr_button.html">
 <link rel="import" href="chrome://downloads/action_service.html">
 <link rel="import" href="chrome://downloads/constants.html">
 <link rel="import" href="chrome://downloads/throttled_icon_loader.html">
 
 <dom-module id="downloads-item">
   <template>
     <div id="date-container">
       <div id="since"></div>
       <div id="date"></div>
     </div>
 
     <div id="content-wrapper">
       <paper-material id="content" on-dragstart="onDragStart_">
         <div class="icon-wrapper">
-          <img id="icon" alt="">
+          <img id="icon" alt="" hidden="[[isDangerous_]]">
+          <div class="warning" hidden="[[!isDangerous_]]"></div>

[groby-ooo-7-16, 2015/08/04 00:56:06]

Curious - why one image, one div?

[Dan Beam, 2015/08/04 01:11:20]

using <img> without any possibility of setting its [src] is confusing

         </div>
 
         <div id="details">
           <div id="title-area"><!-- Can't have any line breaks.
             --><a is="action-link" id="file-link" column-type="name"
                 on-click="onFileLinkClick_"></a><!-- Before #name.
             --><span id="name"></span>
             <span id="tag"></span>
           </div>
 
@@ skipping 41 matching lines @@
     </div>
 
     <div id="end-cap"></div>
 
   </template>
   <link rel="import" type="css" href="chrome://resources/css/action_link.css">
   <link rel="import" type="css" href="chrome://downloads/shared_style.css">
   <link rel="import" type="css" href="chrome://downloads/item.css">
   <script src="chrome://downloads/item.js"></script>
 </dom-module>