Add storage manager overlay on Settings.

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
   <include src="automatic_settings_reset_banner.html">
 <if expr="chromeos">
   <link rel="import" href="chrome://resources/cr_elements/network/cr_network_icon.html">
   <link rel="import" href="chrome://resources/cr_elements/network/cr_onc_types.html">
   <include src="secondary_user_banner.html">
   <section id="network-section-cros">
@@ skipping 111 matching lines @@
       <div class="settings-row">
         <button id="pointer-settings-button" hidden>
         </button>
         <button id="keyboard-settings-button"
             i18n-content="keyboardSettingsButtonTitle">
         </button>
         <span id="display-options-section">
           <button id="display-options" i18n-content="displayOptions" disabled>
           </button>
         </span>
+        <button id="storage-manager-button"
+            i18n-content="storageManagerButtonTitle" hidden>
+        </button>
       </div>
       <div id="power-row" hidden>
         <a is="action-link" id="power-settings-link"
             i18n-content="powerSettingsButton"></a>
       </div>
     </div>
   </section>
 </if>
   <section id="search-section">
     <h3 i18n-content="sectionTitleSearch"></h3>
@@ skipping 970 matching lines @@
       </button>
     </div>
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
   <footer id="advanced-settings-footer">
     <a is="action-link" id="advanced-settings-expander"
         i18n-content="showAdvancedSettings"></a>
   </footer>
 </div>