Able to reproduce the issue on Windows 10, Ubuntu 14.04 and Mac 10.12.6 using chrome stable version #61.0.3163.79 and latest canary #63.0.3214.0.

Bisect Information:
=====================
Good build: 60.0.3080.0	 Revision(466837)
Bad Build : 60.0.3081.0	 Revision(467177)

Change Log URL: 
https://chromium.googlesource.com/chromium/src/+log/bbc102ac1bbea1031b7f8c5ad62ceb04b84dd301..feafc2de2c3e515247b5f45ab9ac9a4139b6cd46

From the above change log suspecting below change
Review URL: https://codereview.chromium.org/2836973002

paulmeyer@ - Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Thanks...!!

This seems to be caused by problems in the internal find algorithm in the PDF find plugin, likely in pdfium_engine.cc: https://cs.chromium.org/chromium/src/pdf/pdfium/pdfium_engine.cc?rcl=c320900e1f204c1b3cc038dbffbf6bc851f72d9a&l=2179

For some reason, the browser is not receiving an active find match until the search completes. Without this first active match, find-next requests cannot be handled (and are thus queued until the first active match is reported).

 Issue 749825  has been merged into this issue.

paulmeyer: Thanks for looking. This sounds like a PDF Viewer bug, and this has been annoying me, so I will take it.

*ping*

Just wanted to check if this is still on anyone's radar? It's been broken and reported for over half a year now ( issue 749825 ), and it really makes working with large technical manuals a pain. Can we assign a target milestone for the fix?

This affects me too. I've been reading Intel processor manuals recently. I looked it this briefly but couldn't quickly fix it. Then I went off to deal with some other bug and never got back around to this.

Comment 3 said the browser is not receiving an active find match. The active find match is triggered by NotifySelectedFindResultChanged() calls, and r467124 moved them all into PDFiumEngine::SelectFindResult(). So I feel like we need to undo some of the PDFiumEngine changes there.

https://chromium-review.googlesource.com/1013748

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c3ea2d2b78f0108debbf6ba56d1b702b63571349

commit c3ea2d2b78f0108debbf6ba56d1b702b63571349
Author: Lei Zhang <thestig@chromium.org>
Date: Thu Apr 26 00:22:23 2018

PDF: Fix find text behavior.

Highlight the first search result immediately after finding it while the
search continues onwards. Instead of waiting for all the search results
to return before highlighting the first search result.

BUG= 764635 

Change-Id: I445ffb88527bd592fc5a51d499ea90d752a88918
Reviewed-on: https://chromium-review.googlesource.com/1013748
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Paul Meyer <paulmeyer@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553843}
[modify] https://crrev.com/c3ea2d2b78f0108debbf6ba56d1b702b63571349/pdf/pdfium/findtext_unittest.cc
[modify] https://crrev.com/c3ea2d2b78f0108debbf6ba56d1b702b63571349/pdf/pdfium/pdfium_engine.cc
[modify] https://crrev.com/c3ea2d2b78f0108debbf6ba56d1b702b63571349/pdf/pdfium/pdfium_engine.h