yamaguchi@ san, could you look into this?

When it failed to get access token (which is always the case in Guest mode),
https://cs.chromium.org/chromium/src/components/chrome_apps/webstore_widget/cws_widget/cws_widget_container.js?sq=package:chromium&q=%22Failed+to+get+Web+Store+access+token%22&l=387

it reject before showing a dialog. Then it's finished as Cancelled by this logic. Since the result is CANCELLED, the alert dialog is not shown neither.
https://cs.chromium.org/chromium/src/ui/file_manager/file_manager/foreground/js/ui/suggest_apps_dialog.js?sq=package:chromium&q=%22Failed+to+start+CWS+widget%22&l=267

Option 1: Return more detailed error object to the reject function so that it can handle this case (result should be FAILED, but dialog is not shown yet) separately from the path above.

Option 2: Read Profile data from the browser process to see if it's guest mode, before attempting to open the suggested apps dialog. (because it's going to fail when getting access token.)
https://cs.chromium.org/chromium/src/ui/file_manager/file_manager/foreground/js/file_tasks.js?q=openSuggestAppsDialog&sq=package:chromium&l=471

I think Option 1 would be better as it'd cover more cases than the guest mode in the future.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8cc2674aa0a8f9da76f18fc55bd8adf4a4730a3b

commit 8cc2674aa0a8f9da76f18fc55bd8adf4a4730a3b
Author: yamaguchi <yamaguchi@chromium.org>
Date: Thu Mar 09 01:44:29 2017

Show alert when failed to get token for opening suggested apps dialog.

This will fix the regression where opening a ZIP file in the Guest mode
gives no feedback.

BUG= 694419 
TEST=Manually tested by opening a zip file in Guest mode.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2740713002
Cr-Commit-Position: refs/heads/master@{#455631}

[modify] https://crrev.com/8cc2674aa0a8f9da76f18fc55bd8adf4a4730a3b/ui/file_manager/file_manager/foreground/js/ui/suggest_apps_dialog.js

Your change meets the bar and is auto-approved for M58. Please go ahead and merge the CL to branch 3029 manually. Please contact milestone owner if you have questions.
Owners: amineer@(clank), cmasso@(bling), bhthompson@(cros), govind@(desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Assigning to fukino@ for merging the change to M58 branch.

This issue has been approved for a merge. Please merge the fix to any appropriate branches as soon as possible!

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The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/890c2e72e2c59b664f5b4f8eba2773d7252bfbbe

commit 890c2e72e2c59b664f5b4f8eba2773d7252bfbbe
Author: Naoki Fukino <fukino@chromium.org>
Date: Thu Mar 16 08:05:25 2017

Show alert when failed to get token for opening suggested apps dialog.

This will fix the regression where opening a ZIP file in the Guest mode
gives no feedback.

BUG= 694419 
TEST=Manually tested by opening a zip file in Guest mode.
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation
TBR=yamaguchi@chromium.org

Review-Url: https://codereview.chromium.org/2740713002
Cr-Commit-Position: refs/heads/master@{#455631}
(cherry picked from commit 8cc2674aa0a8f9da76f18fc55bd8adf4a4730a3b)

Review-Url: https://codereview.chromium.org/2750303002 .
Cr-Commit-Position: refs/branch-heads/3029@{#232}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}

[modify] https://crrev.com/890c2e72e2c59b664f5b4f8eba2773d7252bfbbe/ui/file_manager/file_manager/foreground/js/ui/suggest_apps_dialog.js

Verified Chrome OS version 58.0.3029.31/934.18.0 kevin