https://bugs.chromium.org/p/chromium/issues/detail?id=640696&desc=2#c18

 Issue 756987  has been merged into this issue.

Assigning to myself to investigate for M66.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/814829b1554558562dc68b15a54d17eb49e1e1a9

commit 814829b1554558562dc68b15a54d17eb49e1e1a9
Author: Sasha Morrissey <sashab@chromium.org>
Date: Mon Mar 12 04:30:31 2018

Add drive thumbnails to QuickView for all file types that have thumbnails

thumbnail should appear.

Test: Open a .PDF or .HTML file in Drive in quick view in the Files App. A
Bug:  625944 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I06b8d498b641b3a1c5823617fbe57fa298654bf2
Reviewed-on: https://chromium-review.googlesource.com/952425
Reviewed-by: Keigo Oka <oka@chromium.org>
Commit-Queue: Sasha Morrissey <sashab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542422}
[modify] https://crrev.com/814829b1554558562dc68b15a54d17eb49e1e1a9/ui/file_manager/file_manager/foreground/js/quick_view_controller.js

Weifang,

I've added thumbnail support for all files in Drive that provide thumbnails. Please see the attached screenshots.

This still isn't *quite* the same functionality as local files, since local videos currently can be played in quickview (see quickview_existing_video_local.png vs quickview_video_file.png) and some types of local files don't have any preview, but they do in Drive (see quickview_existing_xls_file.png vs quickview_xls_file.png). Let me know what you think.

Thanks,

Sasha

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Deleted: quickview_mp3_file.png 152 KB

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	quickview_txt_file.png 390 KB View Download

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	quickview_video_file.png 367 KB View Download

Deleted: quickview_xls_file.png 217 KB

	quickview_xls_file.png 217 KB View Download

Deleted: quickview_existing_video_local.png 221 KB

	quickview_existing_video_local.png 221 KB View Download

Deleted: quickview_existing_xls_file.png 137 KB

	quickview_existing_xls_file.png 137 KB View Download

Wow, this is cool. A few questions/comments -
(1) For video files, I think the difference between local/Drive is fine where the video only can be played locally in quick view.
(2) For .xls example, just to confirm - This difference is because Drive generates the preview and we pull it down, whereas we don't have native support for .xls? Curious what the path for supporting this locally would be esp if the user had the MS Excel Android app installed?
(3) Can you confirm that .pdf files on Drive can also be previewed?

Also out of curiosity, will changes be required to the functionality if we switch out the backend with DriveFS?

(1) For video files, I think the difference between local/Drive is fine where the video only can be played locally in quick view.

Great :)

(2) For .xls example, just to confirm - This difference is because Drive generates the preview and we pull it down, whereas we don't have native support for .xls? Curious what the path for supporting this locally would be esp if the user had the MS Excel Android app installed?

Yes, that's correct. I'm also curious :) Some approaches come to mind:
  (a) Push stuff to a Drive API for thumbnailing (needs online though)
  (b) Implement more thumbnail generators locally (to match Drive support)
  (c) Some magical Android thing... Are there file managers for Android that have thumbnails for custom file types? Could be something to look into

(3) Can you confirm that .pdf files on Drive can also be previewed?

Ooh yup, sorry about that. Just the front page is previewed (as it's the thumbnail). Attached a screenshot :)

(4) Also out of curiosity, will changes be required to the functionality if we switch out the backend with DriveFS?

(Just asked sammc@) There is an API in DriveFS to request a thumbnail, so we could just use that and there would be no UI change. :)

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This is fixed. There are multiple approaches to getting complete consistency, but we can discuss them in a future bug. Weifang - feel free to re-open if there's still issues with the solution. :)

Looks good - Thanks for the responses sashab@!

Chrome OS 10575.26.0, 67.0.3396.31