Save most recent 3 destinations across multiple sessions

chrome/browser/resources/print_preview/data/destination_store.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';
 
   /**
    * A data store that stores destinations and dispatches events when the data
    * store changes.
@@ skipping 440 matching lines @@
         return;
       }
 
       var origin = print_preview.Destination.Origin.LOCAL;
       var id = this.systemDefaultDestinationId_;
       var account = '';
       var name = '';
       var capabilities = null;
       var extensionId = '';
       var extensionName = '';
-      if (this.appState_.selectedDestinationId &&
-          this.appState_.selectedDestinationOrigin) {
-        origin = this.appState_.selectedDestinationOrigin;
-        id = this.appState_.selectedDestinationId;
-        account = this.appState_.selectedDestinationAccount || '';
-        name = this.appState_.selectedDestinationName || '';
-        capabilities = this.appState_.selectedDestinationCapabilities;
-        extensionId = this.appState_.selectedDestinationExtensionId || '';
-        extensionName = this.appState_.selectedDestinationExtensionName || '';
+      var foundDestination = false;
+      if (this.appState_.recentDestinationIds &&
+          this.appState_.recentDestinationOrigins) {
+        // Run through the destinations backwards the most recently used is set
+        // as the initially selected destination.
+        for (var i = this.appState_.recentDestinationIds.length - 1; i >= 0;
+             i--) {
+          if (this.appState_.recentDestinationIds[i] &&
+              this.appState_.recentDestinationOrigins[i]) {

[dpapad, 2016/09/21 00:34:30]

Are those two checks necessary?

[rbpotter, 2016/09/21 01:43:07]

Done.

+            origin = this.appState_.recentDestinationOrigins[i];
+            id = this.appState_.recentDestinationIds[i];
+            account = this.appState_.recentDestinationAccounts[i] || '';
+            name = this.appState_.recentDestinationNames[i] || '';
+            capabilities = this.appState_.recentDestinationCapabilities[i];
+            extensionId = this.appState_.recentDestinationExtensionIds[i] || '';
+            extensionName =
+                this.appState_.recentDestinationExtensionNames[i] || '';
+          }
+          var candidate =
+              this.destinationMap_[this.getDestinationKey_(origin,
+                                                           id, account)];
+          if (candidate != null) {
+            this.selectDestination(candidate);
+            candidate.isRecent = true;
+            foundDestination = true;
+          } else {

[dpapad, 2016/09/21 00:34:30]

Can this be simplified as follows?

} else {
  foundDestination = this.fetchPreselectedDestionation_(...);
}

[rbpotter, 2016/09/21 01:43:07]

Done.

+            if (this.fetchPreselectedDestination_(
+              origin,
+              id,
+              account,
+              name,
+              capabilities,
+              extensionId,
+              extensionName)) {
+              foundDestination = true;
+            }
+          }
+        }
       }
+      if (foundDestination) return;
+      // Try the system default
       var candidate =
           this.destinationMap_[this.getDestinationKey_(origin, id, account)];
       if (candidate != null) {
         this.selectDestination(candidate);
         return;
       }
 
       if (this.fetchPreselectedDestination_(
               origin,
               id,
@@ skipping 640 matching lines @@
     /**
      * Inserts a destination into the store without dispatching any events.
      * @return {boolean} Whether the inserted destination was not already in the
      *     store.
      * @private
      */
     insertIntoStore_: function(destination) {
       var key = this.getKey_(destination);
       var existingDestination = this.destinationMap_[key];
       if (existingDestination == null) {
+        for (var destinationIdNum = 0;
+          destinationIdNum < this.appState_.recentDestinationIds.length;

[dpapad, 2016/09/21 00:34:30]

Probably more readable to simply name the iteration counter just "i".

[rbpotter, 2016/09/21 01:43:07]

Done.

+              destinationIdNum++) {
+          if (this.appState_.recentDestinationIds &&

[dpapad, 2016/09/21 00:34:30]

Is this check necessary? Does this.appState_.recentDestinationIds hold
null/undefined values?

[rbpotter, 2016/09/21 01:43:07]

Done.

+              this.appState_.recentDestinationIds[destinationIdNum] &&
+              (destination.id ==
+               this.appState_.recentDestinationIds[destinationIdNum]) &&
+              (destination.origin ==
+               this.appState_.recentDestinationOrigins[destinationIdNum])) {
+             destination.isRecent = true;
+          }
+        }
         this.destinations_.push(destination);
         this.destinationMap_[key] = destination;
         return true;
       } else if (existingDestination.connectionStatus ==
                      print_preview.Destination.ConnectionStatus.UNKNOWN &&
                  destination.connectionStatus !=
                      print_preview.Destination.ConnectionStatus.UNKNOWN) {
         existingDestination.connectionStatus = destination.connectionStatus;
         return true;
       } else {
@@ skipping 331 matching lines @@
       return this.getDestinationKey_(
           destination.origin, destination.id, destination.account);
     }
   };
 
   // Export
   return {
     DestinationStore: DestinationStore
   };
 });