Files.app: Add guard closure for selectedAsyncData.

The FileTransferController#selectedAsyncData is cache of data that cannot be obtained synchronously.
This is needed for assigning the data to DataTransfer in the event handler.
The data can be null if the event is dispatched before the data is obtained.

BUG=431650
TEST=None
TBR=fukino

Review URL: https://codereview.chromium.org/704333003

Cr-Commit-Position: refs/heads/master@{#303444}
(cherry picked from commit 5bb64a5b8ff45d1326552f70f687f378a76af97f)

Review URL: https://codereview.chromium.org/723053002

Cr-Commit-Position: refs/branch-heads/2214@{#24}
Cr-Branched-From: 03655fd3f6d72165dc3c9bd2c89807305316fe6c-refs/heads/master@{#303346}

1 files changed, 4 insertions, 1 deletions

diff --git a/ui/file_manager/file_manager/foreground/js/file_transfer_controller.js b/ui/file_manager/file_manager/foreground/js/file_transfer_controller.js
index 78d4004..cb0c6b1 100644
--- a/ui/file_manager/file_manager/foreground/js/file_transfer_controller.js
+++ b/ui/file_manager/file_manager/foreground/js/file_transfer_controller.js
@@ -200,7 +200,10 @@ FileTransferController.prototype = {
     var externalFileUrl;
     for (var i = 0; i < this.selectedEntries_.length; i++) {
       var url = this.selectedEntries_[i].toURL();
-      dataTransfer.items.add(this.selectedAsyncData_[url].file);
+      if (!this.selectedAsyncData_[url])
+        continue;
+      if (this.selectedAsyncData_[url].file)
+        dataTransfer.items.add(this.selectedAsyncData_[url].file);
       if (!externalFileUrl)
         externalFileUrl = this.selectedAsyncData_[url].externalFileUrl;
     }