Manual regression range;

Good build: 51.0.2696.0
Bad build: 51.0.2698.0

Narrow bisect:
https://chromium.googlesource.com/chromium/src/+log/697d42b85a7a8e9f345d26bb99576c26b7d268a5..e7b73385a8c33c070b28992484dee9657bcefa02?pretty=fuller&n=50

Suspecting: r384489 ?

@alancutter: Kindly help to reassign if your changes are not related to this issue.	

Note: This issue is also reproducible on Mac and Linux OS.

Kindly review the attached screen-cast for reference.

Deleted: Actual_behavior.mp4 1.0 MB

Actual_behavior.mp4 1.0 MB Download

Deleted: Expected_behavior.mp4 2.0 MB

Expected_behavior.mp4 2.0 MB Download

adding RB-label, please change if required.

Looks like it's falling into matrix decomposition, investigating.

Reproducible in Chrome 51.0.2707.23/CrOS 8172.9.0 - Blaze

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b721ba4c7c32b789911cdf125f4871f9b442320b

commit b721ba4c7c32b789911cdf125f4871f9b442320b
Author: alancutter <alancutter@chromium.org>
Date: Tue Apr 26 04:33:00 2016

Don't decompose retargeted rotate() transform transitions

2D rotate() transform operations were always interpolating as 3D rotate()
operations.
This resulted in interpolations between interpolated 2D rotate()s and
matching 2D rotate()s using matrix decomposition as the operation
types no longer matched.

This change ensures non-matrix-decomposition interpolation between
rotate() operations produces the same type of rotate() operation.

BUG= 605021 

Review URL: https://codereview.chromium.org/1909863002

Cr-Commit-Position: refs/heads/master@{#389696}

[add] https://crrev.com/b721ba4c7c32b789911cdf125f4871f9b442320b/third_party/WebKit/LayoutTests/transitions/retargeted-matching-rotation-transforms.html
[modify] https://crrev.com/b721ba4c7c32b789911cdf125f4871f9b442320b/third_party/WebKit/Source/platform/transforms/RotateTransformOperation.cpp

Your change meets the bar and is auto-approved for M51 (branch: 2704)

Please merge your change to M51 branch 2704 before 5:00 PM PST, tomorrow (Friday), so we can take it in for next week M51 beta release. Thank you.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/127afd1b0ee3a6c937e23cd3807f2f144789e41c

commit 127afd1b0ee3a6c937e23cd3807f2f144789e41c
Author: Alan Cutter <alancutter@chromium.org>
Date: Fri Apr 29 04:00:47 2016

Don't decompose retargeted rotate() transform transitions

2D rotate() transform operations were always interpolating as 3D rotate()
operations.
This resulted in interpolations between interpolated 2D rotate()s and
matching 2D rotate()s using matrix decomposition as the operation
types no longer matched.

This change ensures non-matrix-decomposition interpolation between
rotate() operations produces the same type of rotate() operation.

BUG= 605021 

Review URL: https://codereview.chromium.org/1909863002

Cr-Commit-Position: refs/heads/master@{#389696}
(cherry picked from commit b721ba4c7c32b789911cdf125f4871f9b442320b)

Review URL: https://codereview.chromium.org/1926063004 .

Cr-Commit-Position: refs/branch-heads/2704@{#303}
Cr-Branched-From: 6e53600def8f60d8c632fadc70d7c1939ccea347-refs/heads/master@{#386251}

[add] https://crrev.com/127afd1b0ee3a6c937e23cd3807f2f144789e41c/third_party/WebKit/LayoutTests/transitions/retargeted-matching-rotation-transforms.html
[modify] https://crrev.com/127afd1b0ee3a6c937e23cd3807f2f144789e41c/third_party/WebKit/Source/platform/transforms/RotateTransformOperation.cpp

Tested the issue on Windows 7, Mac 10.10.5, Ubuntu 14.04 using 51.0.2704.36.Observed that cube rotated when press and hold up/down/left/right key from keyboard.
Please find attached screencast.

Marking it as TE-Verified.

Deleted: 605021.mp4 2.4 MB

605021.mp4 2.4 MB Download

Verified on 8172.39.0/51.0.2704.55