[CUPS] Re-enable the button to switch to auto-discovery dialog.

chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 
 <link rel="import" href="chrome://resources/html/md_select_css.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-spinner/paper-spinner.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="cups_add_printer_dialog_util.html">
 <link rel="import" href="cups_printers_browser_proxy.html">
@@ skipping 124 matching lines @@
 
       .printer-not-found {
         background-color: var(--paper-yellow-100);
         padding: 10px 20px;
       }
 
       .printer-found {
         background-color: var(--paper-green-100);
         padding: 10px 20px;
       }
+      
+      .dialog-buttons {
+        display: flex;
+        justify-content: space-between;
+        width: 100%;
+      }
     </style>
     <add-printer-dialog>
       <div class="dialog-title">$i18n{addPrintersManuallyTitle}</div>
       <div class="dialog-body">
         <div class="settings-box first two-line">
           <div class="start">
             <div class="label">$i18n{printerName}</div>
             <div class="secondary">
               <paper-input no-label-float id="printerNameInput" autofocus
                   value="{{newPrinter.printerName}}">
@@ skipping 49 matching lines @@
         </div>
         <div class="search-printer-box printer-not-found"
             id="searchNotFound" hidden>
           <span>$i18n{printerNotFound}</span>
         </div>
         <div class="search-printer-box printer-found" id="searchFound" hidden>
           <span>$i18n{printerFound}</span>
         </div>
       </div>
       <div class="dialog-buttons">
-        <paper-button class="cancel-button secondary-button"
-            on-tap="onCancelTap_">
-          $i18n{cancelButtonText}
-        </paper-button>
-        <paper-button class="action-button" on-tap="switchToManufacturerDialog_"
-            disabled="[[!newPrinter.printerName]]">
-          $i18n{addPrinterButtonText}
-        </paper-button>
+        <div>  <!-- Left group -->
+          <paper-button class="secondary-button"
+              on-tap="switchToDiscoveryDialog_">
+            $i18n{discoverPrintersButtonText}
+          </paper-button> 
+        </div>
+        <div>  <!-- Right group -->
+          <paper-button class="cancel-button secondary-button"
+              on-tap="onCancelTap_">
+            $i18n{cancelButtonText}
+          </paper-button>
+          <paper-button class="action-button"
+              on-tap="switchToManufacturerDialog_"
+              disabled="[[!newPrinter.printerName]]">
+            $i18n{addPrinterButtonText}
+          </paper-button>
+        </div>
       </div>
     </add-printer-dialog>
   </template>
 </dom-module>
 
 <dom-module id="add-printer-manufacturer-model-dialog">
   <template>
     <style include="settings-shared">
       .settings-box {
         border-top: none;
@@ skipping 156 matching lines @@
     <!-- Manufacturer and Model Dialog -->
     <template is="dom-if" if="[[showManufacturerDialog_]]" restamp>
       <add-printer-manufacturer-model-dialog new-printer="{{newPrinter}}"
           previous-dialog="[[previousDialog]]" setup-failed="[[setupFailed]]">
       </add-printer-manufacturer-model-dialog>
     </template>
 
   </template>
   <script src="cups_add_printer_dialog.js"></script>
 </dom-module>