[MD History] Disable Clear Browsing Data button for supervised users.

chrome/browser/resources/md_history/history_item.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/cr/ui/focus_row.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/shadow.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://history/browser_service.html">
 <link rel="import" href="chrome://history/constants.html">
 <link rel="import" href="chrome://history/searched_label.html">
@@ skipping 32 matching lines @@
 
       #date-accessed {
         display: none;
       }
 
       :host([is-card-start]) #date-accessed {
         display: block;
       }
 
       #item-container {
+        -webkit-padding-start: 10px;
         align-items: center;
         display: flex;
         min-height: var(--item-height);
         pointer-events: auto;
       }
 
       :host([is-card-start]) #item-container {
         padding-top: var(--card-first-last-item-padding);
       }
 
       :host([is-card-end]) #item-container {
         padding-bottom: var(--card-first-last-item-padding);
       }
 
       #title-and-domain {
         align-items: center;
         display: flex;
         flex: 1;
         height: var(--item-height);
         overflow: hidden;
       }
 
       #checkbox {
-        -webkit-margin-end: 6px;
-        -webkit-margin-start: 10px;
         height: 40px;
         width: 40px;
       }
 
       :host([selected]) #checkbox {
         color: var(--interactive-color);
       }
 
       #checkmark {
         border: 2px solid var(--secondary-text-color);
@@ skipping 25 matching lines @@
       }
 
       :host([selected]) #checkmark::after {
         border-color: white;
         transform: scale(1) rotate(45deg);
         /* Only animate when showing checkmark. */
         transition: transform 140ms ease-out;
       }
 
       #time-accessed {
+        -webkit-margin-start: 6px;
         color: var(--history-item-time-color);
         min-width: 96px;
       }
 
       #domain {
         -webkit-margin-start: 16px;
         color: var(--secondary-text-color);
         flex-shrink: 0;
       }
 
@@ skipping 71 matching lines @@
       <div id="background-clip">
         <div id="background"></div>
       </div>
       <div id="date-accessed" class="card-title">
         [[cardTitle_(numberOfItems, item.dateRelativeDay, searchTerm)]]
       </div>
       <div id="item-container"
           on-mousedown="onItemMousedown_"
           on-click="onItemClick_">
         <button is="paper-icon-button-light" id="checkbox"
-            disabled="[[selectionNotAllowed_()]]"
+            hidden="[[selectionNotAllowed_]]"
             role="checkbox"
             aria-checked$="[[getAriaChecked_(selected)]]"
             aria-label$="[[getEntrySummary_(item)]]">
           <div id="checkmark"></div>
         </button>
         <span id="time-accessed" on-mouseover="addTimeTitle_">
           [[item.readableTimestamp]]
         </span>
         <div class="website-icon" id="icon"></div>
         <div id="title-and-domain">
@@ skipping 19 matching lines @@
           <div></div>
           <div></div>
           <div></div>
         </button>
       </div>
       <div id="time-gap-separator" hidden="[[!hasTimeGap]]"></div>
     </div>
   </template>
   <script src="chrome://history/history_item.js"></script>
 </dom-module>