Update CUPS settings UI to allow USB printers to be added via discovery.

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

Index: chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html
diff --git a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html
index 867ac2c9afabe2f0c7f0263862122e8af716bdc9..2971c01f41eb55421a3f8f39705c4553e34ede31 100644
--- a/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html
+++ b/chrome/browser/resources/settings/printing_page/cups_add_printer_dialog.html
@@ -75,7 +75,7 @@
           </paper-button>
           <paper-button class="action-button" id="addPrinterButton"
               disabled="[[!selectedPrinter]]"
-              on-tap="switchToConfiguringDialog_">
+              on-tap="switchToManufacturerDialog_">
             $i18n{addPrinterButtonText}
           </paper-button>
         </div>
@@ -317,8 +317,8 @@
       <div class="dialog-buttons">
         <div>  <!-- Left group -->
           <paper-button id="manuallyAddPrinterButton" class="secondary-button"
-              on-tap="switchToManualAddDialog_">
-            $i18n{manuallyAddPrinterButtonText}
+              on-tap="switchToManualAddDialog_" hidden="[[!inManualFlow]]">

[xdai1, 2017/05/11 00:25:10]

Unrelated question: If we want to modify this button to be a back button, why
don't we have it for discovery flow as well? Clicking on the back button either
directs the user to the manual dialog or to the discovery dialog seems more
reasonable? (btw: was weifangsun@ aware of this button change?)

[Carlson, 2017/05/11 22:08:58]

Good point on both parts.

We discussed options offline.  I've pinged, but haven't heard back from Weifang,
but I'd really like to get the top level change in for M60, so for now I've
implemented this as 'back' in both the discovery and manual case, which is sort
of the minimal change that makes things orthogonal.  I recognize that we may
change this ui decision later, but I think it's not worth holding up the change?

+            $i18n{back}
           </paper-button>
         </div>
         <div>  <!-- Right group -->
@@ -387,7 +387,8 @@
     <!-- Manufacturer and Model Dialog -->
     <template is="dom-if" if="[[showManufacturerDialog_]]" restamp>
       <add-printer-manufacturer-model-dialog new-printer="{{newPrinter}}"
-          setup-failed="[[setupFailed]]">
+          selected-printer="{{selectedPrinter}}" setup-failed="[[setupFailed]]"
+          in-manual-flow="[[inManualFlow]]">
       </add-printer-manufacturer-model-dialog>
     </template>