Fix CrOS reverting to Save as PDF and random PDF preview fail

chrome/browser/resources/print_preview/data/app_state.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.define('print_preview', function() {
   'use strict';
 
   /**
    * Object used to represent a recent destination in the app state.
    * @constructor
@@ skipping 119 matching lines @@
      * Helper function to get the most recent destination.
      * @return {?RecentDestination} The most recent value of the
      *     destination.
      */
     getSelectedDestination_: function() {
       return (this.state_[AppState.Field.RECENT_DESTINATIONS].length > 0) ?
           this.state_[AppState.Field.RECENT_DESTINATIONS][0] : null;
     },
 
     /** @return {?string} ID of the selected destination. */
     get selectedDestinationId() {

[dpapad, 2016/11/18 00:33:20]

I am also wondering why are all these getters (line 140-187). Can't all callers
use a single getter (selectedDestination at line 193)?

[rbpotter, 2016/11/18 02:59:22]

Done. They were here because they were here before I made this change, so I left
them in and just updated them to work with the new code. Apparently only 2 of
them were ever used...

-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.id : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().id : null;
     },
 
     /** @return {?string} Account the selected destination is registered for. */
     get selectedDestinationAccount() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.account : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().account : null;
     },
 
     /**
      * @return {?print_preview.Destination.Origin<string>} Origin of the
      *     selected destination.
      */
     get selectedDestinationOrigin() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.origin : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().origin : null;
     },
 
     /** @return {?print_preview.Cdd} CDD of the selected destination. */
     get selectedDestinationCapabilities() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.capabilities : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().capabilities : null;
     },
 
     /** @return {?string} Name of the selected destination. */
     get selectedDestinationName() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.name : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().name : null;
     },
 
     /**
      * @return {?string} Extension ID associated with the selected destination.
      */
     get selectedDestinationExtensionId() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.extensionId : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().extensionId : null;
     },
 
     /**
      * @return {?string} Extension name associated with the selected
      *     destination.
      */
     get selectedDestinationExtensionName() {
-      return this.getSelectedDestination_ ?
-          this.getSelectedDestination_.extensionName : null;
+      return this.getSelectedDestination_() ?
+          this.getSelectedDestination_().extensionName : null;
     },
 
     /**
      * @return {?RecentDestination} The most recent destination, which is
      *     currently the selected destination.
      */
     get selectedDestination() {
-      return this.getSelectedDestination_;
+      return this.getSelectedDestination_();
     },
 
     /**
      * @return {?Array<!RecentDestination>} The AppState.NUM_DESTINATIONS_ most
      *     recent destinations.
      */
     get recentDestinations() {
       return this.state_[AppState.Field.RECENT_DESTINATIONS];
     },
 
@@ skipping 87 matching lines @@
         this.state_[field] = value;
       }
       this.persist_();
     },
 
     /**
      * Persists the selected destination.
      * @param {!print_preview.Destination} dest Destination to persist.
      */
     persistSelectedDestination: function(dest) {
-      if (!this.isInitialized_)
+      if (!this.isInitialized_ || !dest)

[dpapad, 2016/11/18 00:33:20]

Also per the type annotation !print_preview.Destination above, |dest| should
never be null/undefined, so this checks seems odd. Can you either update the
annotation or remove the check if not necessary?

[rbpotter, 2016/11/18 02:59:23]

Removed this and updated the place it was getting called with a null
destination.

         return;
 
       // Determine if this destination is already in the recent destinations,
       // and where in the array it is located.
       var newDestination = new RecentDestination(dest);
       var indexFound = this.state_[
           AppState.Field.RECENT_DESTINATIONS].findIndex(function(recent) {
             return (newDestination.id == recent.id &&
                     newDestination.origin == recent.origin);
           });
@@ skipping 40 matching lines @@
     persist_: function() {
       chrome.send(AppState.NATIVE_FUNCTION_NAME_,
                   [JSON.stringify(this.state_)]);
     }
   };
 
   return {
     AppState: AppState
   };
 });