I'm gonna have a go on this issue...

This is a part of  bug 64309 .

I'll actually remove this from the scope of  bug 64309  and reopen it. It's a specific enough issue that it doesn't need to be in that bug.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/97f071cf3276dcac200033a933fe8fee7a709d20

commit 97f071cf3276dcac200033a933fe8fee7a709d20
Author: Henrique Nakashima <hnakashima@chromium.org>
Date: Thu Jan 11 19:56:02 2018

PDF bookmarks targets transformed on demand rather than on load.

This decreases load time, especially for PDFs with lots of bookmarks
such as books.

Also, this message is necessary for subsequent changes implementing
nameddests with XYZ positioning.

Bug: 55776,535978,748852
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Id1d7b87fd8c16b2f748d11bf61b8f78aa80d0b94
Reviewed-on: https://chromium-review.googlesource.com/850924
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528717}
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/browser/resources/component_extension_resources.grd
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/browser/resources/pdf/compiled_resources2.gyp
[add] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/browser/resources/pdf/coords_transformer.js
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/browser/resources/pdf/index.html
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/browser/resources/pdf/pdf.js
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/chrome/test/data/pdf/bookmarks_test.js
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/out_of_process_instance.cc
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/pdf_engine.h
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/pdfium/pdfium_engine.cc
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/pdfium/pdfium_engine.h
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/pdfium/pdfium_page.cc
[modify] https://crrev.com/97f071cf3276dcac200033a933fe8fee7a709d20/pdf/pdfium/pdfium_page.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9d1b2d650c92110085d153fdaaa5670720b08678

commit 9d1b2d650c92110085d153fdaaa5670720b08678
Author: Henrique Nakashima <hnakashima@chromium.org>
Date: Thu Feb 08 20:50:58 2018

Create PDFViewer.postMessage_().

Refactor usages of this.plugin_.postMessage() to use this method.

This makes it easier to pass a callback to other objects that sends
a message to the PPAPI plugin.

Bug: 55776,535978,748852
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I7ccd7df56f55d0ef099f590ba9e13c8bff9e3cfb
Reviewed-on: https://chromium-review.googlesource.com/907232
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535503}
[modify] https://crrev.com/9d1b2d650c92110085d153fdaaa5670720b08678/chrome/browser/resources/pdf/open_pdf_params_parser.js
[modify] https://crrev.com/9d1b2d650c92110085d153fdaaa5670720b08678/chrome/browser/resources/pdf/pdf.js
[modify] https://crrev.com/9d1b2d650c92110085d153fdaaa5670720b08678/chrome/test/data/pdf/navigator_test.js
[modify] https://crrev.com/9d1b2d650c92110085d153fdaaa5670720b08678/chrome/test/data/pdf/params_parser_test.js

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d13b1b5876e78bf52925cdeacfbd6e3438c7e4ad

commit d13b1b5876e78bf52925cdeacfbd6e3438c7e4ad
Author: Henrique Nakashima <hnakashima@chromium.org>
Date: Fri Feb 09 00:30:27 2018

Switch pdfium_engine.cc to use FPDFDest_GetDestPageIndex().

The previously used FPDFDest_GetPageIndex() is deprecated and is
incorrect. The return value for error is 0, which is also a valid
value. FPDFDest_GetDestPageIndex() uses -1 as error value.

Bug: 55776,535978,748852, pdfium:938 
Change-Id: I96fa379bd1679d987da81321e763d1bb6c3022fd
Reviewed-on: https://chromium-review.googlesource.com/909928
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535591}
[modify] https://crrev.com/d13b1b5876e78bf52925cdeacfbd6e3438c7e4ad/pdf/pdfium/pdfium_engine.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/363e99ad2603c4336062115dab3a1b8f28200d27

commit 363e99ad2603c4336062115dab3a1b8f28200d27
Author: Henrique Nakashima <hnakashima@chromium.org>
Date: Fri Feb 09 23:24:05 2018

GetNamedDestination() returns more info about PDF destination.

Previously called GetNamedDestinationPage(), the new version returns
the view and view parameters in a PDFEngine::NamedDestination
struct.

Bug: 55776,535978,748852
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I5410ed66715e3c579e5daa89231cf89dbeaf83e9
Reviewed-on: https://chromium-review.googlesource.com/910208
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535877}
[modify] https://crrev.com/363e99ad2603c4336062115dab3a1b8f28200d27/pdf/out_of_process_instance.cc
[modify] https://crrev.com/363e99ad2603c4336062115dab3a1b8f28200d27/pdf/pdf_engine.h
[modify] https://crrev.com/363e99ad2603c4336062115dab3a1b8f28200d27/pdf/pdfium/pdfium_engine.cc
[modify] https://crrev.com/363e99ad2603c4336062115dab3a1b8f28200d27/pdf/pdfium/pdfium_engine.h

Any news on this? Got hit by this bug recently while working on a navigation for PDF lecture scripts and it is really a blocker for me...

See discussion in crbug.com/55776 for the status.

Thanks for the information and working on this bug!