Move content deduplication into the scan process.

ui/file_manager/file_manager/background/js/background.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.
 
 /**
  * Type of a Files.app's instance launch.
  * @enum {number}
  */
 var LaunchType = {
   ALWAYS_CREATE: 0,
@@ skipping 61 matching lines @@
    * @type {!DriveSyncHandler}
    */
   this.driveSyncHandler = new DriveSyncHandler(this.progressCenter);
 
   /**
    * Provides support for scaning media devices as part of Cloud Import.
    * @type {!importer.MediaScanner}
    */
   this.mediaScanner = new importer.DefaultMediaScanner(
       importer.createMetadataHashcode,
-      this.historyLoader,
+      importer.DispositionChecker.createChecker(
+          this.historyLoader,
+          this.tracker),
       importer.DefaultDirectoryWatcher.create);
 
   /**
    * Handles importing of user media (e.g. photos, videos) from removable
    * devices.
    * @type {!importer.MediaImportHandler}
    */
-  this.mediaImportHandler =
-      new importer.MediaImportHandler(
-          this.progressCenter,
-          this.historyLoader,
-          new importer.DriveDuplicateFinder.Factory(),
-          this.tracker);
+  this.mediaImportHandler = new importer.MediaImportHandler(
+      this.progressCenter,
+      this.historyLoader,
+      this.tracker);
 
   /**
    * Promise of string data.
    * @private {!Promise}
    */
   this.initializationPromise_ = this.startInitialization_();
 
   /**
    * String assets.
    * @type {Object<string, string>}
@@ skipping 525 matching lines @@
 // NOTE: This must be called before FileBrowserBackground is instantiated.
 // TODO(kenobi): Revisit this once users have the ability to do this themselves.
 metrics.clearUserId();
 
 /**
  * Singleton instance of Background.
  * NOTE: This must come after the call to metrics.clearUserId.
  * @type {FileBrowserBackground}
  */
 window.background = new FileBrowserBackground();