[MD settings] CSS var --checkbox-spacing to --settings-control-spacing

chrome/browser/resources/settings/date_time_page/date_time_page.html

 <link rel="import" href="chrome://resources/html/cr.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_pref_indicator.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-toggle-button/paper-toggle-button.html">
 <link rel="import" href="../controls/settings_dropdown_menu.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../prefs/prefs_behavior.html">
 <link rel="import" href="../prefs/prefs_types.html">
 <link rel="import" href="../settings_shared_css.html">
 
 <dom-module id="settings-date-time-page">
   <template>
     <style include="settings-shared">
       .embedded {
         -webkit-padding-start: var(--settings-box-row-indent);
       }
 
       settings-dropdown-menu {
         --md-select-width: 400px;
       }
 
       paper-toggle-button,
       cr-policy-pref-indicator {
-        -webkit-margin-start: var(--checkbox-spacing);
+        -webkit-margin-start: var(--settings-control-spacing);
       }
     </style>
     <div class="settings-box first">
       <div id="timezoneGeolocateToggleLabel" class="start">
         $i18n{timeZoneGeolocation}
       </div>
       <template is="dom-if" if="[[hasTimeZoneAutoDetectPolicy_]]" restamp>
         <cr-policy-pref-indicator pref="[[fakeTimeZonePolicyPref_]]"
             icon-aria-label="$i18n{timeZoneGeolocation}">
         </cr-policy-pref-indicator>
@@ skipping 20 matching lines @@
     </div>
     <div class="settings-box" id="setDateTime" actionable
         on-tap="onSetDateTimeTap_" hidden$="[[!canSetDateTime_]]">
       <div class="start">$i18n{setDateTime}</div>
       <button class="subpage-arrow" is="paper-icon-button-light"
           aria-label="$i18n{setDateTime}"></button>
     </div>
   </template>
   <script src="date_time_page.js"></script>
 </dom-module>