> In Chrome 67, only the larger garbage can is visible. See the attached Chrome screenshot.

Clarification: The larger garbage can and the checkmark are visible (but not the smaller garbage can)

Bisected to r552511 = a016ca5071c9d0a3848a2c55fd0e13339d27d994
"[SPv175+] Don't create transform operations for identity transforms"
Landed in 68.0.3402.0
Merged to 67.0.3396.17

Confirmed by disabling SP175 via "--disable-blink-features=SlimmingPaintV175" 
command line and observing the bug is gone.

The bug occurs when mapping from:
root
  PaintOffsetTranslation {}
    PaintOffsetTranslation {"matrix":translation(21,17,0)}
      Transform {"matrix":"scale(6.16356e-05,6.16356e-05,1)","origin":"0,0,0"}

to 
root
  PaintOffsetTranslation {}
    PaintOffsetTranslation {"matrix":translation(21,17,0)}

The correct result should be the inversion of the scale transform, but the actual result is an identity transform.

A simple fix is to simplify the identity condition just to check if the child transform is identity. This can cover most of the cases that two consecutive clips can be combined.

The root cause seems that we treat the Scale(6e-5, 6e-5) transformation is non-invertible, but based on this bug, it seems reasonable that an SVG is defined using huge dimensions then scaled down to a tiny icon. Should we loose the condition of Isinvertible?

An observation is that AffineTransform::IsInvertible is much more lax than TransformationMatrix::IsInvertible (the former is just != 0.)

(FWIW though, I would not recommend using unnecessarily large values in viewBox for exactly reasons like this.)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b0708fdad511e82684a474b12fd932026ea33a12

commit b0708fdad511e82684a474b12fd932026ea33a12
Author: Xianzhu Wang <wangxianzhu@chromium.org>
Date: Tue Jun 05 21:59:36 2018

[PE] Relax TransformationMatrix::IsInvertible

Previously it treated transforms with abs(determinant) less than 1e-8 as
non-invertible. This was too strict that transforms like Scale(9.9e-5)
were treated as non-invertible.

Now just check if determinant is zero, which is consistent with
AffineTransform and SkMatrix[44].

The code was added here:
https://chromium.googlesource.com/chromium/src/+/041f0d1e8d01d8dc0cd2f4fe2579e1f09a9ae27a
in an initial commit of 3D transforms.

Bug:  849382 
Change-Id: I01e395f373493f61fcf85851b694be9aed7b41c5
Reviewed-on: https://chromium-review.googlesource.com/1087362
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564680}
[modify] https://crrev.com/b0708fdad511e82684a474b12fd932026ea33a12/third_party/blink/renderer/platform/transforms/transformation_matrix.cc
[modify] https://crrev.com/b0708fdad511e82684a474b12fd932026ea33a12/third_party/blink/renderer/platform/transforms/transformation_matrix_test.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/717c1c2988ffba7c956ec3c0d00b9225fe2c48a1

commit 717c1c2988ffba7c956ec3c0d00b9225fe2c48a1
Author: Xianzhu Wang <wangxianzhu@chromium.org>
Date: Wed Jun 06 22:55:50 2018

[PE] Don't combine clips across non-invertible transform

GeometryMapper::SourceToDestinationProjection(parent, child) returns
identity if child transform is not invertible, so it's not reliable
to use it to check if parent and child are in the same transform space.

Now avoid the function, while still handle most common cases to combine
clips through identity transforms.

Bug:  849382 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I747e857d3828a5fb6eea0f69ed8746843912baf4
Reviewed-on: https://chromium-review.googlesource.com/1086492
Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565078}
[modify] https://crrev.com/717c1c2988ffba7c956ec3c0d00b9225fe2c48a1/third_party/blink/renderer/platform/graphics/compositing/paint_chunks_to_cc_layer.cc
[modify] https://crrev.com/717c1c2988ffba7c956ec3c0d00b9225fe2c48a1/third_party/blink/renderer/platform/graphics/compositing/paint_chunks_to_cc_layer_test.cc

Request to merge the CL in #c8. 

This bug requires manual review: M68 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), kariahda@(iOS), bhthompson@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Approved. branch:3440

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/cef4e5301177e9bc00923c4d13993b01fbbcc4a4

commit cef4e5301177e9bc00923c4d13993b01fbbcc4a4
Author: Xianzhu Wang <wangxianzhu@chromium.org>
Date: Mon Jun 11 15:59:10 2018

[PE] Don't combine clips across non-invertible transform

GeometryMapper::SourceToDestinationProjection(parent, child) returns
identity if child transform is not invertible, so it's not reliable
to use it to check if parent and child are in the same transform space.

Now avoid the function, while still handle most common cases to combine
clips through identity transforms.

TBR=wangxianzhu@chromium.org

(cherry picked from commit 717c1c2988ffba7c956ec3c0d00b9225fe2c48a1)

Bug:  849382 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: I747e857d3828a5fb6eea0f69ed8746843912baf4
Reviewed-on: https://chromium-review.googlesource.com/1086492
Reviewed-by: Tien-Ren Chen <trchen@chromium.org>
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#565078}
Reviewed-on: https://chromium-review.googlesource.com/1095423
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/branch-heads/3440@{#276}
Cr-Branched-From: 010ddcfda246975d194964ccf20038ebbdec6084-refs/heads/master@{#561733}
[modify] https://crrev.com/cef4e5301177e9bc00923c4d13993b01fbbcc4a4/third_party/blink/renderer/platform/graphics/compositing/paint_chunks_to_cc_layer.cc
[modify] https://crrev.com/cef4e5301177e9bc00923c4d13993b01fbbcc4a4/third_party/blink/renderer/platform/graphics/compositing/paint_chunks_to_cc_layer_test.cc

Verified the fix on Ubuntu 14.04 using Chrome version #68.0.3440.25 as per the comment#0.
Attaching screen shot for reference.
Observed that three SVG images are seen upon opening index.html
Hence, the fix is working as expected. 
Adding the verified labels.
Note: Able to reproduce the issue on chrome version 67.0.3396.62

Thanks...!!