MD Settings: give Chrome logo an alt text

chrome/browser/resources/settings/about_page/about_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="about_page_browser_proxy.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../icons.html">
 <link rel="import" href="../lifetime_browser_proxy.html">
 <link rel="import" href="../route.html">
 <link rel="import" href="../settings_page/main_page_behavior.html">
 <link rel="import" href="../settings_page/settings_animated_pages.html">
 <link rel="import" href="../settings_page/settings_section.html">
 <link rel="import" href="../settings_page_css.html">
@@ skipping 68 matching lines @@
       }
 </if>
     </style>
     <div>
       <settings-section page-title="$i18n{aboutPageTitle}" section="about">
         <settings-animated-pages id="pages" section="about">
           <neon-animatable route-path="default">
             <div class="settings-box two-line">
               <img id="product-logo" on-tap="onProductLogoTap_"
                   srcset="chrome://theme/current-channel-logo@1x 1x,
-                          chrome://theme/current-channel-logo@2x 2x" alt="">
+                          chrome://theme/current-channel-logo@2x 2x"
+                  alt="$i18n{aboutProductLogoAlt}">
               <span class="product-title">$i18n{aboutProductTitle}</span>
             </div>
             <div class="settings-box two-line">
               <!-- TODO(dpapad): Investigate why vulcanize does not handle well
                 a new line after "getIconSrc_(", causes incorrect src URL -->
               <iron-icon
                   hidden="[[!showUpdateStatus_]]"
                   icon$="[[getIcon_(
                       obsoleteSystemInfo_, currentUpdateStatusEvent_)]]"
                   src="[[getIconSrc_(obsoleteSystemInfo_, currentUpdateStatusEvent_)]]">
@@ skipping 111 matching lines @@
               <settings-detailed-build-info></settings-detailed-build-info>
             </settings-subpage>
           </template>
 </if>
         </settings-animated-pages>
       </settings-section>
     </div>
   </template>
   <script src="about_page.js"></script>
 </dom-module>