Files.app: Add deduplication code for imports to Google Drive.

ui/file_manager/file_manager/background/js/media_import_handler.js

Index: ui/file_manager/file_manager/background/js/media_import_handler.js
diff --git a/ui/file_manager/file_manager/background/js/media_import_handler.js b/ui/file_manager/file_manager/background/js/media_import_handler.js
index 0135363a2493de1a1392f2277b1cf3c93141a121..9c62f45f4bf072cfd9be5ef625a3f6e5839ffec2 100644
--- a/ui/file_manager/file_manager/background/js/media_import_handler.js
+++ b/ui/file_manager/file_manager/background/js/media_import_handler.js
@@ -311,7 +311,7 @@ importer.MediaImportHandler.ImportTask.prototype.importOne_ =
             if (isDuplicate) {
               // If the given file is a duplicate, don't import it again.  Just
               // update the progress indicator.
-              // TODO(kenobi): Update import history to mark the dupe as sync'd.
+              this.markAsImported_(entry);
               this.processedBytes_ += entry.size;
               this.notify(importer.TaskQueue.UpdateType.PROGRESS);
               return Promise.resolve();
@@ -427,6 +427,22 @@ importer.MediaImportHandler.ImportTask.prototype.markAsCopied_ =
       });
 };
 
+/**
+ * @param {!FileEntry} entry
+ * @param {!DirectoryEntry} destination
+ */
+importer.MediaImportHandler.ImportTask.prototype.markAsImported_ =
+    function(entry) {
+  this.remainingFilesCount_--;
+  this.historyLoader_.getHistory().then(
+      /** @param {!importer.ImportHistory} history */
+      function(history) {
+        history.markImported(
+            entry,
+            importer.Destination.GOOGLE_DRIVE);
+      });
+};
+
 /** @private */
 importer.MediaImportHandler.ImportTask.prototype.onSuccess_ = function() {
   this.notify(importer.TaskQueue.UpdateType.SUCCESS);