The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/907fc9acbc83330a08e6d9a94d97d0bf6ffafd7b

commit 907fc9acbc83330a08e6d9a94d97d0bf6ffafd7b
Author: Luna Lu <loonybear@chromium.org>
Date: Tue Mar 13 15:39:02 2018

Mark editing/pasteboard/drag-files-to-editable-element.html flaky on Linux

Bug: 821455
Change-Id: I49c24c67d5eec2672829ceb9eeaa5f63019d20a3
Reviewed-on: https://chromium-review.googlesource.com/960572
Commit-Queue: Luna Lu <loonybear@chromium.org>
Reviewed-by: Luna Lu <loonybear@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542810}
[modify] https://crrev.com/907fc9acbc83330a08e6d9a94d97d0bf6ffafd7b/third_party/WebKit/LayoutTests/TestExpectations

Culprit? https://chromium-review.googlesource.com/c/chromium/src/+/758236

can you please provide a link to a failing build?

I took a look at this test. There is a bug, the <script> executes test expectations after the document has been loaded. The issue is that the test doesn't uses TestRunner::WaitUntilDone(). So it often finishes before it tests anything.

Depending on timing, the test may:
1) Finish without executing the assertions -> Test PASS
2) Finish with executing the assertions-> Test FAIL:
   ~~~[output]~~~
   Could not load the requested resource.
   Error code: -6 (net::ERR_FILE_NOT_FOUND)
   ~~~~~~~~~~~~~~

It fails because the files "foo", "bar" and "baz" don't exists. I tried adding them, but it turns out the drag and drop causes the browser to navigate, which is not supposed to happen. It means there is a real regression.

I mark myself as owner the time to update the test.

+CC dcheng@ (as an owner of Blink>DataTransfer) and japhet@

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/250cef84d714b3386a3910845842ea12c3a7abed

commit 250cef84d714b3386a3910845842ea12c3a7abed
Author: Arthur Sonzogni <arthursonzogni@chromium.org>
Date: Wed Jun 13 11:37:25 2018

Fix test: drag-files-to-editable-element.html

The tested feature regressed, but no one realized it, because the test continued
to pass.

Instead of displaying the filenames in the <div>, a new navigation to the file
happened. Starting the navigation causes the current Document to stop and the
test to finish early. The tests finished before it has executed any assertions.

This CL fixes the test, but not the regression.

Bug: 821455, 831155
Change-Id: I61b9cca80677ca2caed72b0e9cf6074f73c2ad6a
Reviewed-on: https://chromium-review.googlesource.com/1094879
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566800}
[modify] https://crrev.com/250cef84d714b3386a3910845842ea12c3a7abed/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/250cef84d714b3386a3910845842ea12c3a7abed/third_party/WebKit/LayoutTests/editing/pasteboard/drag-files-to-editable-element.html
[add] https://crrev.com/250cef84d714b3386a3910845842ea12c3a7abed/third_party/WebKit/LayoutTests/editing/pasteboard/resources/drag-files-to-editable-element-fail

Test is fixed and is now properly failing.
We still need to fix the regression.