Attachment 1
    File name - remap mime type.png
    Description - 3rd party browser apps are remapping mime type

Attachment 2
    File name - 20160324_104833.mp4
    Description - Screen recording of reproducible steps

Deleted: remap mime type.png 36.7 KB

	remap mime type.png 36.7 KB View Download

The mime type of downloaded image is "application/octet-stream".
But many 3rd party browser apps remap "application/octet-stream" to "image/jpeg" like attachment "remap mime type.png".

And I find out remapGenericMimeType API and maybe Chrome can use similar function to solve this problem.

https://android.googlesource.com/platform/frameworks/base/+/marshmallow-mr1-release/core/java/android/webkit/MimeTypeMap.java#126

Could you consider remapping mime type to "imaage/jpeg"?

Thanks.

Issue reproducible, tested on Nexus5X/6.0, chrome stable: 49.0.2623.105.

Logs @ http://go/chrome-androidlogs1/5/597914

Note: Issue frequency 3/5

Gentle reminder

changwan@ or qinmin@ are better suited to investigate than I

Gentle reminder

Gentle reminder

Sorry, but m.dcinside.com isn't accessible outside Korea. It seems that they block foreign IP addresses. Could you provide a more concrete, non-dcinside URL? Thanks.

It is reproducible at "https://weather.com".
The mime-type of downloaded image is "application/unknown".

Gentle reminder

Hmm... We call DownloadManager#addCompletedDownload() with the same mime type "application/octet-stream" whether it is replaced or newly created.
But forcing the value to "image/jpeg" in DownloadManagerService.java actually seems to fix the problem for the replaced scenario.

qinmin@, could you take a look? I'm not quite familiar with how mime types are propagated.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2f54b5c49b1fe73dd179ac34e81a3d2575ef8cb7

commit 2f54b5c49b1fe73dd179ac34e81a3d2575ef8cb7
Author: qinmin <qinmin@chromium.org>
Date: Mon Aug 22 22:10:45 2016

Fix an issue that android doesn't know how to open the download after completion

When downloading a file, the Mime type could be generic.
Chrome used to callremapGenericMimeType for downloads going through Android
DownloadManager.
It should do the same for downloads handled by Chrome's network stack.

BUG= 597914 

Review-Url: https://codereview.chromium.org/2261323002
Cr-Commit-Position: refs/heads/master@{#413550}

[modify] https://crrev.com/2f54b5c49b1fe73dd179ac34e81a3d2575ef8cb7/chrome/android/java/src/org/chromium/chrome/browser/download/ChromeDownloadDelegate.java
[modify] https://crrev.com/2f54b5c49b1fe73dd179ac34e81a3d2575ef8cb7/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java