[CUPS] Put the CUPS settings UI behind a command line flag --enable-native-cups.

chrome/browser/resources/settings/printing_page/printing_page.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/neon-animation/neon-animatable.html">
 <link rel="import" href="/icons.html">
 <link rel="import" href="/printing_page/cloud_printers.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_page/settings_animated_pages.html">
 <link rel="import" href="/settings_page/settings_subpage.html">
 <link rel="import" href="/settings_shared_css.html">
 <if expr="chromeos">
 <link rel="import" href="/printing_page/cups_printer_details_page.html">
 <link rel="import" href="/printing_page/cups_printers.html">
 </if>
 
 <dom-module id="settings-printing-page">
   <template>
     <style include="settings-shared"></style>
     <settings-animated-pages id="pages" section="printing">
       <array-selector id="arraySelector" items="{{cupsPrinters}}"
           selected="{{detailPrinter_}}">
       </array-selector>
       <neon-animatable route-path="default">
 <if expr="chromeos">
-        <div id="cupsPrinters" class="settings-box first"
-            on-tap="onTapCupsPrinters_" actionable>
-          <iron-icon icon="cr:print"></iron-icon>
-          <div class="middle">$i18n{cupsPrintersTitle}</div>
-        </div>
+        <template is="dom-if" if="[[showCupsPrintingFeatures_]]">
+          <div id="cupsPrinters" class="settings-box first"
+              on-tap="onTapCupsPrinters_" actionable>
+            <iron-icon icon="cr:print"></iron-icon>
+            <div class="middle">$i18n{cupsPrintersTitle}</div>
+          </div>
+        </template>
 </if>
         <div id="cloudPrinters" class="settings-box"
             on-tap="onTapCloudPrinters_" actionable>
           <iron-icon icon="settings:cloud-printing"></iron-icon>
           <div class="middle">$i18n{cloudPrintersTitle}</div>
         </div>
       </neon-animatable>
 <if expr="chromeos">
       <template is="dom-if" route-path="/cupsPrinters">
         <settings-subpage
@@ skipping 18 matching lines @@
             associated-control="[[$$('#cloudPrinters')]]"
             page-title="$i18n{cloudPrintersTitle}">
           <settings-cloud-printers prefs="{{prefs}}">
           </settings-cloud-printers>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="printing_page.js"></script>
 </dom-module>