Print Preview: Merge NativeLayerStubs for tests

chrome/browser/resources/print_preview/native_layer.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.
 
 cr.exportPath('print_preview');
 
 /**
  * @typedef {{selectSaveAsPdfDestination: boolean,
  *            layoutSettings.portrait: boolean,
  *            pageRange: string,
@@ skipping 62 matching lines @@
         this.onPrintPresetOptionsFromDocument_.bind(this);
     global.onProvisionalPrinterResolved =
         this.onProvisionalDestinationResolved_.bind(this);
     global.failedToResolveProvisionalPrinter =
         this.failedToResolveProvisionalDestination_.bind(this);
 
     /** @private {!cr.EventTarget} */
     this.eventTarget_ = new cr.EventTarget();
   }
 
+  /** @private {print_preview.NativeLayer} */

[dpapad, 2017/05/19 20:59:29]

?print_preview.NativeLayer

[rbpotter, 2017/05/20 00:43:59]

Done.

+  var currentInstance = null;
+
+  /**
+   * @return {!print_preview.NativeLayer} an instance of NativeLayer.

[dpapad, 2017/05/19 20:59:29]

Nit:
"an instance of NativeLayer." -> "The singleton instance."

[rbpotter, 2017/05/20 00:43:59]

Done.

+   * Creates a new NativeLayer if the current instance is not set.
+   */
+  NativeLayer.getInstance = function() {
+    if (currentInstance)

[dpapad, 2017/05/19 20:59:29]

This condition should be reversed I think. Also let's compare to null directly.

[rbpotter, 2017/05/20 00:43:59]

Done.

+      currentInstance = new NativeLayer();
+    return assert(currentInstance);
+  };
+
+  /**
+   * @param {!print_preview.NativeLayer} instance The NativeLayer instance
+   *     to set for print preview construction.
+   */
+  NativeLayer.setInstance = function(instance) {
+    currentInstance = instance;
+  };
+
   /**
    * Event types dispatched from the Chromium native layer.
    * @enum {string}
    * @const
    */
   NativeLayer.EventType = {
     ACCESS_TOKEN_READY: 'print_preview.NativeLayer.ACCESS_TOKEN_READY',
     CAPABILITIES_SET: 'print_preview.NativeLayer.CAPABILITIES_SET',
     CLOUD_PRINT_ENABLE: 'print_preview.NativeLayer.CLOUD_PRINT_ENABLE',
     DESTINATIONS_RELOAD: 'print_preview.NativeLayer.DESTINATIONS_RELOAD',
@@ skipping 1002 matching lines @@
       return this.serializedDefaultDestinationSelectionRulesStr_;
     }
   };
 
   // Export
   return {
     NativeInitialSettings: NativeInitialSettings,
     NativeLayer: NativeLayer
   };
 });