Check for RPCS printers and return error if Win8+

chrome/browser/resources/print_preview/previewarea/preview_area.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @typedef {{accessibility: Function,
  *            documentLoadComplete: Function,
  *            getHeight: Function,
  *            getHorizontalScrollbarThickness: Function,
  *            getPageLocationNormalized: Function,
@@ skipping 288 matching lines @@
     setPluginKeyEventCallback: function(callback) {
       this.keyEventCallback_ = callback;
     },
 
     /**
      * Shows a custom message on the preview area's overlay.
      * @param {string} message Custom message to show.
      */
     showCustomMessage: function(message) {
       this.showMessage_(PreviewArea.MessageId_.CUSTOM, message);
+      if (this.loadingTimeout_) {

[dpapad, 2017/03/08 23:37:01]

The same logic to clear the timeout is repeated in other places in this file,
see onPreviewGenerationFailed and onPluginLoaded. Can we create a
cancelTimeout() helper method instead and use it in all places?

Having said that, I am still trying to understand the case where we need to
cancel the timeout here. I don't fully understand why it is now the
responsibility of showCustomMessage() to do anything about the timeout. Is there
a more appropriate place we could move this, outside showCustomMessage?

[rbpotter, 2017/03/09 00:42:48]

Refactored.

I moved this into print_preview in onSettingsInvalid_, the function
that calls this. Let me know if this seems like a more reasonable
place for it.

+        // If this is true another event that triggered a "Preview Loading..."
+        // message arrived just before this one and the timeout will cause
+        // this message to be overwritten when it expires. Clear the timeout
+        // so this doesn't occur.
+        clearTimeout(this.loadingTimeout_);
+        this.loadingTimeout_ = null;
+      }
     },
 
     /** @override */
     enterDocument: function() {
       print_preview.Component.prototype.enterDocument.call(this);
 
       this.tracker.add(
           assert(this.openSystemDialogButton_),
           'click',
           this.onOpenSystemDialogButtonClick_.bind(this));
@@ skipping 347 matching lines @@
       // being draggable.
       this.plugin_.style.pointerEvents = isDragging ? 'none' : 'auto';
     }
   };
 
   // Export
   return {
     PreviewArea: PreviewArea
   };
 });