Looks like the test is hanging/timing out. Here's the failure log (repeated 4 times):
WebUIWebViewBrowserTest.DragAndDropToInput (run #1):
[ RUN      ] WebUIWebViewBrowserTest.DragAndDropToInput
[4944:3164:1012/172142:INFO:CONSOLE(7548)] "Running test testDragAndDropToInput", source: webview_basic.js (7548)
[4944:3164:1012/172142:INFO:CONSOLE(11053)] "load stop of src = :about:blank", source: webview_basic.js (11053)
[4944:3164:1012/172142:INFO:CONSOLE(5)] "start guest js", source:  (5)
[4944:3164:1012/172142:INFO:CONSOLE(11064)] "[Guest]: start guest js", source: webview_basic.js (11064)
[4944:3164:1012/172142:INFO:CONSOLE(50)] "finish guest js", source:  (50)
[4944:3164:1012/172142:INFO:CONSOLE(11064)] "[Guest]: finish guest js", source: webview_basic.js (11064)
[4944:3164:1012/172142:INFO:CONSOLE(11056)] "finish guest load", source: webview_basic.js (11056)
[4944:3164:1012/172142:INFO:CONSOLE(10)] "guest gets message create-channel", source:  (10)
[4944:3164:1012/172142:INFO:CONSOLE(11064)] "[Guest]: guest gets message create-channel", source: webview_basic.js (11064)
[4944:3164:1012/172142:INFO:CONSOLE(18)] "guest posts message: connected", source:  (18)
[4944:3164:1012/172142:INFO:CONSOLE(11064)] "[Guest]: guest posts message: connected", source: webview_basic.js (11064)
[4944:3164:1012/172142:INFO:CONSOLE(11041)] "get message: connected", source: webview_basic.js (11041)
[4944:3164:1012/172142:INFO:CONSOLE(1)] "step1: Drag Enter", source:  (1)

... eventually ...

[513/513] WebUIWebViewBrowserTest.DragAndDropToInput (TIMED OUT)
1 test timed out:
    WebUIWebViewBrowserTest.DragAndDropToInput (c:\b\c\b\win\src\chrome\browser\ui\webui\webui_webview_browsertest.cc:262)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b8ccefa34e0b710e40be7ace25ebdcb22de57a9b

commit b8ccefa34e0b710e40be7ace25ebdcb22de57a9b
Author: kulshin <kulshin@chromium.org>
Date: Thu Oct 13 01:45:20 2016

Disable WebUIWebViewBrowserTest.DragAndDropToInput

Disable WebUIWebViewBrowserTest.DragAndDropToInput due to failures and
no obvious cause in regression range:
https://chromium.googlesource.com/chromium/src/+log/2cbfc042012e00bc5863caa8c55de9d25f71d5e3%5E..ac744d9d74ee1e9a6a6d8af344481d59f04bebdc?pretty=fuller

Note that the test failed previously in https://uberchromegw.corp.google.com/i/chromium.win/builders/Win%207%20Tests%20x64%20%281%29/builds/17530
and https://uberchromegw.corp.google.com/i/chromium.win/builders/Win%207%20Tests%20x64%20%281%29/builds/17472
(and possibly others) so regression range may not be accurate.

BUG=655433
NOTRY=true
TBR=bauerb@chromium.org

Review-Url: https://codereview.chromium.org/2415853002
Cr-Commit-Position: refs/heads/master@{#424934}

[modify] https://crrev.com/b8ccefa34e0b710e40be7ace25ebdcb22de57a9b/chrome/browser/ui/webui/webui_webview_browsertest.cc

 Issue 613407  has been merged into this issue.

 Issue 655302  has been merged into this issue.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

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

WebUI team might take this.