Able to reproduce the issue on reported chrome version #71.0.3578.80, latest stable #71.0.3578.98 and latest chrome #73.0.3650.0 using Windows 10, Ubuntu 17.10 and Mac 10.13.6 by following steps as per comment#0. The fooloe=wing is the bisect information.

Bisect Information:
===================
Good build: 61.0.3135.0
Bad build: 61.0.3136.0

You are probably looking for a change made after 480609 (known good), but no later than 480610 (first known bad).
CHANGELOG URL:https://chromium.googlesource.com/chromium/src/+log/e4467a74bf0377e884e890209a773aec61682a41..ad1b882e19f56b75b1a6c11203148d56c3e95e6b
Suspecting On: https://pdfium.googlesource.com/pdfium.git/+/b73ce7bcd72a97c780176d9f63681a5415c06422
Reviewed-on: https://pdfium-review.googlesource.com/6610

@Henrique Nakashima: Please help us in reassigning the issue if it is not related to your change.
Thanks.!

Perhaps this is WAI. Assigning to Lei to triage.

It's weird the History code is willing to accept and display an empty entry. Maybe they can offer some recommendations on how the PDF Viewer should behave in cases like this.

@John: Can you take a look? Perhaps we should be displaying a string even when there is no title for a certain page? Something like "No title - file://...", or we should at least have a clickable area even when no title exists.

FWIW, foo.html with <title></title> causes Blink to display "foo.html" as the title. Is the History code designed with this in mind so it never assume this issue can happen? If so, we can definitely work around this in the PDF Viewer.

Also, the PDF Viewer does handle missing titles just fine, but in this case, the title consists of a single U+F020 character.

History code also makes sure the title isn't empty and falls back to the URL if it is: https://cs.chromium.org/chromium/src/chrome/browser/ui/webui/browsing_history_handler.cc?q=browsing_history_handler&sq=package:chromium&g=0&l=111

Maybe we can make the favicon as part of the click target (similar to how bookmarks look) on the History page so that even if a title is very small (like in this case, nothing visible), users are still able to click through?

This is also not PDF-specific. The same issue can occur for:

<title></title> <!-- There's a U+F020 char inside. //-->

Moved the icon into the clickable target for now so that users can click on the icon if the title is too short/not visible.

https://chromium-review.googlesource.com/c/chromium/src/+/1403615

See outlines in screenshots for when they are focused.

Deleted: history 1.png 21.4 KB

	history 1.png 21.4 KB View Download

Deleted: history 2.png 28.1 KB

	history 2.png 28.1 KB View Download

This issue has an owner, a component and a priority, but is still listed as untriaged or unconfirmed. By definition, this bug is triaged. Changing status to "assigned". Please reach out to me if you disagree with how I've done this.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/634656bfde3c7a51b832007e64d5cc0a6aba5e8a

commit 634656bfde3c7a51b832007e64d5cc0a6aba5e8a
Author: John Lee <johntlee@chromium.org>
Date: Wed Jan 16 23:12:06 2019

History WebUI: Move favicon into clickable target for link in history item

Bug:  917565 
Change-Id: I5ab5eb5cbeff8e92146a1cb46a026a832259813d
Reviewed-on: https://chromium-review.googlesource.com/c/1403615
Commit-Queue: John Lee <johntlee@chromium.org>
Reviewed-by: calamity <calamity@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623434}
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/browser/resources/md_history/history_item.html
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/browser/resources/md_history/history_item.js
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/browser/resources/md_history/shared_style.html
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/browser/resources/md_history/synced_device_card.html
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/browser/resources/md_history/synced_device_card.js
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/test/data/webui/md_history/history_list_test.js
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/test/data/webui/md_history/history_metrics_test.js
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/test/data/webui/md_history/history_synced_tabs_test.js
[modify] https://crrev.com/634656bfde3c7a51b832007e64d5cc0a6aba5e8a/chrome/test/data/webui/md_history/md_history_focus_test.js