Add support for size checking selection based scans.

ui/file_manager/file_manager/background/js/media_scanner.js

 // Copyright 2014 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.
 
 /**
  * Class representing the results of a scan operation.
  *
  * @interface
  */
 importer.MediaScanner = function() {};
@@ skipping 117 matching lines @@
   }
 };
 
 /** @override */
 importer.DefaultMediaScanner.prototype.scan = function(entries) {
   if (entries.length == 0) {
     throw new Error('Cannot scan empty list of entries.');
   }
 
   var scanResult = this.createScanResult_();
-  var watcher = this.watcherFactory_(function() {
-    scanResult.invalidateScan();
-    this.observers_.forEach(
-        /** @param {!importer.ScanObserver} observer */
-        function(observer) {
-          observer(importer.ScanEvent.INVALIDATED, scanResult);
-        });
-  }.bind(this));
+  var watcher = this.watcherFactory_(
+      /** @this {importer.DefaultMediaScanner} */
+      function() {
+        scanResult.invalidateScan();
+        this.observers_.forEach(
+            /** @param {!importer.ScanObserver} observer */
+            function(observer) {
+              observer(importer.ScanEvent.INVALIDATED, scanResult);
+            });
+      }.bind(this));
   var scanPromises = entries.map(
       this.scanEntry_.bind(this, scanResult, watcher));
 
   Promise.all(scanPromises)
-      .then(scanResult.resolveScan.bind(scanResult))
-      .catch(scanResult.rejectScan.bind(scanResult));
+      .then(scanResult.resolve)
+      .catch(scanResult.reject);
 
   scanResult.whenFinal()
       .then(
           function() {
             this.onScanFinished_(scanResult);
           }.bind(this));
 
   return scanResult;
 };
 
@@ skipping 110 matching lines @@
    * @type {Date}
    */
   this.scanStarted_ = new Date();
 
   /**
    * The point in time when the last scan activity occured.
    * @type {Date}
    */
   this.lastScanActivity_ = this.scanStarted_;
 
-  /** @private {boolean} */
-  this.settled_ = false;
+  /** @private {!importer.Resolver.<!importer.ScanResult>} */
+  this.resolver_ = new importer.Resolver();
+};
 
-  /** @type {function()} */
-  this.resolveScan;
+/** @struct */
+importer.DefaultScanResult.prototype = {
 
-  /** @type {function(*)} */
-  this.rejectScan;
+  /** @return {function()} */

[Ben Kwa, 2015/01/30 23:13:09]

I think this is the reason your refactoring addressed the type issue: the type
of the resolve function being passed to the .then call above has gone back to
{function()}, whereas in your intermediate code it was... something else.

[Steve McKay, 2015/01/30 23:18:02]

But the issue was only when I had individually selected files...not for all
scans. Seems like if the issue was related to the original code...then it would
have affected *all* scans.

+  get resolve() { return this.resolver_.resolve.bind(null, this); },
 
-  /** @private {!Promise.<!importer.ScanResult>} */
-  this.finishedPromise_ = new Promise(
-      function(resolve, reject) {
-        this.resolveScan = function() {
-          this.settled_ = true;
-          resolve(this);
-        }.bind(this);
-
-        this.rejectScan = function() {
-          this.settled_ = true;
-          reject();
-        };
-      }.bind(this));
+  /** @return {function(*=)} */
+  get reject() { return this.resolver_.reject; }
 };
 
 /** @override */
 importer.DefaultScanResult.prototype.isFinal = function() {
-  return this.settled_;
+  return this.resolver_.settled;
 };
 
 importer.DefaultScanResult.prototype.isInvalidated = function() {
   return this.invalidated_;
 };
 
 /** @override */
 importer.DefaultScanResult.prototype.getFileEntries = function() {
   return this.fileEntries_;
 };
 
 /** @override */
 importer.DefaultScanResult.prototype.getTotalBytes = function() {
   return this.totalBytes_;
 };
 
 /** @override */
 importer.DefaultScanResult.prototype.getScanDurationMs = function() {
   return this.lastScanActivity_.getTime() - this.scanStarted_.getTime();
 };
 
 /** @override */
 importer.DefaultScanResult.prototype.whenFinal = function() {
-  return this.finishedPromise_;
+  return this.resolver_.promise;
 };
 
 /**
  * Invalidates this scan.
  */
 importer.DefaultScanResult.prototype.invalidateScan = function() {
   this.invalidated_ = true;
 };
 
 /**
@@ skipping 155 matching lines @@
   if (!this.watchedDirectories_[event.entry.toURL()])
     return;
   this.triggered = true;
   for (var url in this.watchedDirectories_) {
     chrome.fileManagerPrivate.removeFileWatch(url, function() {});
   }
   chrome.fileManagerPrivate.onDirectoryChanged.removeListener(
       assert(this.listener_));
   this.callback_();
 };