Add autoclick to settings page under the accessibility section.

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
 <if expr="not pp_ifdef('chromeos')">
   <include src="sync_section.html">
 </if>
 <if expr="pp_ifdef('chromeos')">
   <section>
     <h3 i18n-content="sectionTitleInternet"></h3>
@@ skipping 729 matching lines @@
       </div>
       <div class="option-name" id="accessibility-tap-dragging">
         <div class="checkbox">
           <label>
             <input id="accessibility-tap-dragging-check"
                 pref="settings.touchpad.enable_tap_dragging" type="checkbox">
             <span i18n-content="accessibilityTapDragging"></span>
           </label>
         </div>
       </div>
+      <div class="setting-row option-name" id="accessibility-autoclick" hidden>
+        <div class="checkbox">
+          <input id="accessibility-autoclick-check"
+              pref="settings.a11y.autoclick" type="checkbox">
+        </div>
+        <div id="accessibility-autoclick-subrow">
+          <div>
+            <label for="accessibility-autoclick-check"
+                i18n-content="accessibilityAutoclick">
+            </label>
+            <span class="controlled-setting-indicator"
+                pref="settings.a11y.autoclick">
+            </span>
+          </div>
+          <div>
+            <label class="option-name" for="accessibility-autoclick-dropdown"
+                i18n-content="accessibilityAutoclickDropdown">
+            </label>
+            <select id="accessibility-autoclick-dropdown" class="control"
+              data-type="number"
+              pref="settings.a11y.autoclick_delay_ms">
+              <option value="200"
+                  i18n-content="autoclickDelayExtremelyShort"></option>
+              <option value="400"
+                  i18n-content="autoclickDelayVeryShort"></option>
+              <option value="600" i18n-content="autoclickDelayShort"></option>
+              <option value="800" i18n-content="autoclickDelayLong"></option>
+              <option value="1000"
+                  i18n-content="autoclickDelayVeryLong"></option>
+            </select>
+            <span class="controlled-setting-indicator"
+                pref="settings.a11y.autoclick_delay_ms">
+            </span>
+          </div>
+        </div>
+      </div>
   </section>
 <if expr="pp_ifdef('chromeos')">
   <section id="factory-reset-section" hidden>
     <h3 i18n-content="factoryResetTitle"></h3>
     <div>
       <span class="settings-row" i18n-content="factoryResetDescription">
       </span>
       <button id="factory-reset-restart"
           i18n-content="factoryResetRestart">
       </button>
@@ skipping 46 matching lines @@
     </div>
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
   <footer>
     <button id="advanced-settings-expander" class="link-button"
         i18n-content="showAdvancedSettings">
     </button>
   </footer>
   </div>