Using the per-revision bisect providing the bisect results,
Good build:61.0.3134.0(Revision:480301).
Bad build:61.0.3135.0(Revision:480321).

You are probably looking for a change made after 480301 (known good), but no later than 480302 (first known bad).

CHANGE-LOG URL:
---------------
https://chromium.googlesource.com/chromium/src/+log/d6653466e313dc83a33ec049a6eef95a31dda435..de5f24293bb231a3d770b731b0aadf549cab86ae

From the CL above, assigning the issue to the concern owner

@fmalita : Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.

Reviewed-On:https://chromium-review.googlesource.com/538335
Note :Mac specific issue and Able to reproduce in latest Canary #61.0.3156.0
Adding Release Block-Stable for this issue.Please remove if not the case.

Hmm, so it's not the built-in preview but some external PDF app?  Possibly a bug in the external viewer - Hal, WDYT?

I'll work on a minimal test case first.

halcanary@ Ping! Since this issue is marked as RB-Stable, Could you please let us know is there any latest update available on this bug?

Thanks!

Looks like Preview.app is having trouble with transparency.

(The shadow (which is encoded as a jpeg image) is just rendering as a translucent grey square.

Adobe reader is having the same issue.  I'll send out some queries.

Attached is an even simpler test case.

Deleted: BLUR_SIMPLE.pdf 1.8 KB

BLUR_SIMPLE.pdf 1.8 KB Download

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/b4bd5ef99c99745959a9f1eb208d558da163d8d8

commit b4bd5ef99c99745959a9f1eb208d558da163d8d8
Author: Hal Canary <halcanary@google.com>
Date: Wed Jul 26 16:13:29 2017

SkPDF: Use DeviceGray for alpha masks.

See https://groups.google.com/forum/#!topic/pdf-dev/qmdjg3w7D8E

BUG= chromium:742058 
Change-Id: Ia8c204a92cb2b9fc33fab60826a95e359db65f08
Reviewed-on: https://skia-review.googlesource.com/26822
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>

[modify] https://crrev.com/b4bd5ef99c99745959a9f1eb208d558da163d8d8/src/pdf/SkPDFDevice.cpp
[modify] https://crrev.com/b4bd5ef99c99745959a9f1eb208d558da163d8d8/src/pdf/SkPDFDevice.h

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/89dbf5f34908c9c16709bb26958d68442736eb84

commit 89dbf5f34908c9c16709bb26958d68442736eb84
Author: skia-deps-roller@chromium.org <skia-deps-roller@chromium.org>
Date: Wed Jul 26 19:04:36 2017

Roll src/third_party/skia/ a9340ba98..e82a10bb1 (11 commits)

https://skia.googlesource.com/skia.git/+log/a9340ba98050..e82a10bb183b

$ git log a9340ba98..e82a10bb1 --date=short --no-merges --format='%ad %ae %s'
2017-07-26 liyuqian Use ifdef instead of ifndef
2017-07-26 halcanary SkPDF: Use DeviceGray for alpha masks.
2017-07-25 liyuqian Fix viewer state that has empty state/option
2017-07-26 reed add Make factory to SkMemoryStream (simplify call-sites)
2017-07-26 caryclark generated documentation for SkPaint
2017-07-26 reed remove codec-api flag
2017-07-26 brianosman Normalize canvas tracing
2017-07-26 liyuqian Further reduce stack size according to -fstack-usage
2017-07-26 brianosman Automatically prepend "disabled-by-default-" to TRACE categories
2017-07-26 mtklein ok, exit() child processes instead of _exit()
2017-07-26 liyuqian Further reduce google3 stack size

Created with:
  roll-dep src/third_party/skia
BUG= 742058 


Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, see:
http://www.chromium.org/developers/tree-sheriffs/sheriff-details-chromium#TOC-Failures-due-to-DEPS-rolls


CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=kjlubick@chromium.org

Change-Id: I707611c6776205521753f1aa3355aabc9033ddd0
Reviewed-on: https://chromium-review.googlesource.com/586973
Reviewed-by: Skia Deps Roller <skia-deps-roller@chromium.org>
Commit-Queue: Skia Deps Roller <skia-deps-roller@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489716}
[modify] https://crrev.com/89dbf5f34908c9c16709bb26958d68442736eb84/DEPS

URGENT - PTAL.
Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and get it merged into the M61 branch #3163 ASAP to have enough baking time in Beta before Stable promotion. Thank you!

Know that this issue shouldn't block the release?  Remove the ReleaseBlock-Stable label.

Fixed in m62.  Will cherry-picking back to m61 now.

Rechecked this issue on chrome version 62.0.3168.0 on MAC 10.12.6. Fix is working as intended. PDF preview is displayed fine. Attached screen shot for the same.

Adding TE-Verified labels for M62. Requesting a merge for M61

Thanks.!

Deleted: Print-Preview.png 217 KB

	Print-Preview.png 217 KB View Download

The following revision refers to this bug:
  https://skia.googlesource.com/skia/+/20ea7747f0db83718af1affd8bb72881f85ab0f7

commit 20ea7747f0db83718af1affd8bb72881f85ab0f7
Author: Hal Canary <halcanary@google.com>
Date: Thu Jul 27 13:49:03 2017

SkPDF: Use DeviceGray for alpha masks. [cherry-pick]

See https://groups.google.com/forum/#!topic/pdf-dev/qmdjg3w7D8E

BUG= chromium:742058 
Reviewed-on: https://skia-review.googlesource.com/26822
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>

Change-Id: Ic2bf132624d581c53e979732f17752828602d83d
Reviewed-on: https://skia-review.googlesource.com/27360
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>

[modify] https://crrev.com/20ea7747f0db83718af1affd8bb72881f85ab0f7/src/pdf/SkPDFDevice.cpp
[modify] https://crrev.com/20ea7747f0db83718af1affd8bb72881f85ab0f7/src/pdf/SkPDFDevice.h

Fixed, needs checking when new version of m61 rolls out.

ranjitkan@ (re: #13), next time pls update bug saying "please request a merge to M61" instead of "Requesting merge to M61" to avoid confusion and getting changes get merged without approval.

halcanary@,
CL listed at #14 got merged to M61 without approval. Next time please request  a merge to M61 by applying "Merge-Request-61" label and wait for approval. 

I see change has been verified on Canary at #13. Could you please confirm this change is well baked and it is a safe merge to M61?

Thank you.