This is first going to require a design doc and intent to implement for frames().

It looks like it would be fairly straightforward, needing:
- a new TimingFunction subclass (https://cs.chromium.org/chromium/src/third_party/WebKit/Source/platform/animation/TimingFunction.h)
- maybe a new CSS*TimingFunctionValue (https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h)
- hooks into the CSS and parsing code (https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp, https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp, https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp)
- and, of course, tests.

I don't have bandwidth to take this on right now, so I'm going to unassign again (sorry, Alan).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e

commit 1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e
Author: suzyh <suzyh@chromium.org>
Date: Thu Apr 20 06:24:23 2017

Implement frames() timing function

This patch adds support for the frames timing function defined in
https://www.w3.org/TR/css-timing-1/#frames-timing-functions, based on
the implementation for the steps timing function.

BUG=646265
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2775143002
Cr-Commit-Position: refs/heads/master@{#465916}

[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/cc/animation/keyframed_animation_curve_unittest.cc
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/cc/animation/timing_function.cc
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/cc/animation/timing_function.h
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/animations/animations-parsing-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/animations/animations-parsing.html
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/animations/timing-functions-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/animations/timing-functions.html
[delete] https://crrev.com/9d28c22de85528d1f87bfbf3f88dc531027b24bd/third_party/WebKit/LayoutTests/external/wpt/css-timing-1/frames-timing-functions-output-expected.txt
[delete] https://crrev.com/9d28c22de85528d1f87bfbf3f88dc531027b24bd/third_party/WebKit/LayoutTests/external/wpt/css-timing-1/frames-timing-functions-syntax-expected.txt
[delete] https://crrev.com/9d28c22de85528d1f87bfbf3f88dc531027b24bd/third_party/WebKit/LayoutTests/external/wpt/web-animations/interfaces/AnimationEffectTiming/easing-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/external/wpt/web-animations/timing-model/time-transformations/transformed-progress-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/platform/linux/external/wpt/web-animations/animation-model/keyframe-effects/effect-value-transformed-distance-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/platform/mac/external/wpt/web-animations/animation-model/keyframe-effects/effect-value-transformed-distance-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/platform/win/external/wpt/web-animations/animation-model/keyframe-effects/effect-value-transformed-distance-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/transitions/transitions-parsing-expected.txt
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/LayoutTests/transitions/transitions-parsing.html
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/animation/AnimationInputHelpersTest.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/animation/CompositorAnimationsTest.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/animation/TimingInputTest.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/CSSValue.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/CSSValue.h
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/CSSValueKeywords.json5
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/platform/animation/TimingFunction.cpp
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/platform/animation/TimingFunction.h
[modify] https://crrev.com/1b0bb2fe0fb6094a235a10b4e7d921c9b04e6d2e/third_party/WebKit/Source/platform/animation/TimingFunctionTest.cpp

The frames() timing function should now be in the next release of Chrome (60).

The next step on this issue is to send an intent to deprecate and remove for step-middle, targeting 61 for deprecation and 62 for removal. So, next action will be in a month or so.

M60 has branched, so I'll start looking at the deprecation of step-middle now.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4cd8966bc2b20f69b9b23d2538eb25452775134e

commit 4cd8966bc2b20f69b9b23d2538eb25452775134e
Author: suzyh <suzyh@chromium.org>
Date: Tue Jun 13 06:37:17 2017

Deprecate step timing with position 'middle'

This patch adds a deprecation warning and UseCounter for instances of
the step animation timing function with step position 'middle' and the
keyword 'step-middle'.

This patch also adds a dummy document to TimingInputTest in order to
maintain the invariant that if step-middle is allowed then a non-null
Document* is provided for the UseCounter.

BUG=646265

Review-Url: https://codereview.chromium.org/2927123005
Cr-Commit-Position: refs/heads/master@{#478914}

[add] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/LayoutTests/animations/step-middle-keyword-timing-function-deprecated-expected.txt
[add] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/LayoutTests/animations/step-middle-keyword-timing-function-deprecated.html
[add] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/LayoutTests/animations/step-middle-timing-function-deprecated-expected.txt
[add] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/LayoutTests/animations/step-middle-timing-function-deprecated.html
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/LayoutTests/animations/timing-functions.html
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/Source/core/animation/AnimationInputHelpers.cpp
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/Source/core/animation/TimingInputTest.cpp
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.cpp
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/Source/core/css/resolver/CSSToStyleMap.h
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/Source/core/frame/Deprecation.cpp
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/third_party/WebKit/public/platform/WebFeature.h
[modify] https://crrev.com/4cd8966bc2b20f69b9b23d2538eb25452775134e/tools/metrics/histograms/enums.xml

Next action here is at the end of July/beginning of August. Next steps are to:

- check the usage of the DeprecatedTimingFunctionStepMiddle use counter, which I think will be here:
https://www.chromestatus.com/metrics/feature/timeline/popularity/2024

- reply on the blink-dev thread with the use counter stats, in order to confirm approval to remove
https://groups.google.com/a/chromium.org/d/topic/blink-dev/gTFAvEYSuEQ/discussion

- (subject to approval above) remove support for step-middle after we branch for M61

Due to spec instability over the name "frames" we have decided to abort shipping frames().
https://github.com/w3c/csswg-drafts/issues/1301
https://chromium-review.googlesource.com/c/552218/

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ffcd346677e9dd28037da9619c510274d9318bfe

commit ffcd346677e9dd28037da9619c510274d9318bfe
Author: Alan Cutter <alancutter@chromium.org>
Date: Fri Jun 30 01:43:19 2017

Unship frames() animation timing function

This patch unships the frames() animation timing function due to
unresolved issues over the naming.

No intent is required as the timing function has not reached the
stable channel of Chrome yet.

Ongoing spec discussion:
https://github.com/w3c/csswg-drafts/issues/1301

Bug: 646265
Change-Id: Ice19051813a96eaa55229e46ef6630a75333b5b8
Reviewed-on: https://chromium-review.googlesource.com/552218
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Suzy Howlett <suzyh@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#483584}
[add] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/LayoutTests/virtual/stable/animations-unprefixed/frames-timing-function.html
[modify] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h
[modify] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
[modify] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/Source/platform/animation/TimingFunction.h
[modify] https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe/third_party/WebKit/Source/platform/animation/TimingFunctionTest.cpp

Requesting to merge ffcd346677e9dd28037da9619c510274d9318bfe into M60 beta.
This is to prevent us shipping a web feature that may become spec incompatible in the near future.

The bug is marked as P3 or Feature. It should not be merged as M60 is in beta. 
Please contact the approriate milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

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

+bustamante:
Could you please do a manual review of this merge request? We wish to revert the feature from M60.

Ping: bustamante

I'm out on vacation until monday, abdulsyed@ do you mind taking a look?

We are planning to pref-off frames() in release/beta channels in Gecko too.
Bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1379582

bustamante/abdulsyed: ping?

Ping: abdulsyed

We are attempting to co-ordinate with Firefox to avoid shipping a web feature that's under spec contention. Please manually review the request to merge https://crrev.com/ffcd346677e9dd28037da9619c510274d9318bfe into M60.

This bug requires manual review: We are only 11 days from stable.
Please contact the milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

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

Approving merge for M60. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f4fc014f1342eba26b8febacb518247f0207a712

commit f4fc014f1342eba26b8febacb518247f0207a712
Author: Alan Cutter <alancutter@chromium.org>
Date: Tue Jul 18 00:14:46 2017

Unship frames() animation timing function

This patch unships the frames() animation timing function due to
unresolved issues over the naming.

No intent is required as the timing function has not reached the
stable channel of Chrome yet.

Ongoing spec discussion:
https://github.com/w3c/csswg-drafts/issues/1301

TBR=alancutter@chromium.org

(cherry picked from commit ffcd346677e9dd28037da9619c510274d9318bfe)

Bug: 646265
Change-Id: Ice19051813a96eaa55229e46ef6630a75333b5b8
Reviewed-on: https://chromium-review.googlesource.com/552218
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Suzy Howlett <suzyh@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#483584}
Reviewed-on: https://chromium-review.googlesource.com/574988
Reviewed-by: Alan Cutter <alancutter@chromium.org>
Cr-Commit-Position: refs/branch-heads/3112@{#628}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
[add] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/LayoutTests/virtual/stable/animations-unprefixed/frames-timing-function.html
[modify] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h
[modify] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
[modify] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/Source/platform/animation/TimingFunction.h
[modify] https://crrev.com/f4fc014f1342eba26b8febacb518247f0207a712/third_party/WebKit/Source/platform/animation/TimingFunctionTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fd23350d864d212a74bbcfa17a91a96dc4991810

commit fd23350d864d212a74bbcfa17a91a96dc4991810
Author: Alex Mineer <amineer@chromium.org>
Date: Tue Jul 18 18:51:37 2017

Revert "Unship frames() animation timing function"

This reverts commit f4fc014f1342eba26b8febacb518247f0207a712.

Reason for revert: Causing build failure:

../../third_party/WebKit/Source/platform/animation/TimingFunction.h:219:12: error: 'FramesTimingFunctionEnabled' is not a member of 'blink::RuntimeEnabledFeatures'
     DCHECK(RuntimeEnabledFeatures::FramesTimingFunctionEnabled());
            ^

https://uberchromegw.corp.google.com/i/official.android.continuous/builders/beta-arm/builds/8762/steps/Build%20libchrome.so/logs/stdio

BUG=646265

Original change's description:
> Unship frames() animation timing function
> 
> This patch unships the frames() animation timing function due to
> unresolved issues over the naming.
> 
> No intent is required as the timing function has not reached the
> stable channel of Chrome yet.
> 
> Ongoing spec discussion:
> https://github.com/w3c/csswg-drafts/issues/1301
> 
> TBR=alancutter@chromium.org
> 
> (cherry picked from commit ffcd346677e9dd28037da9619c510274d9318bfe)
> 
> Bug: 646265
> Change-Id: Ice19051813a96eaa55229e46ef6630a75333b5b8
> Reviewed-on: https://chromium-review.googlesource.com/552218
> Commit-Queue: Alan Cutter <alancutter@chromium.org>
> Reviewed-by: Suzy Howlett <suzyh@chromium.org>
> Reviewed-by: Noel Gordon <noel@chromium.org>
> Cr-Original-Commit-Position: refs/heads/master@{#483584}
> Reviewed-on: https://chromium-review.googlesource.com/574988
> Reviewed-by: Alan Cutter <alancutter@chromium.org>
> Cr-Commit-Position: refs/branch-heads/3112@{#628}
> Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

TBR=noel@chromium.org,alancutter@chromium.org,suzyh@chromium.org

Change-Id: I85ff5ade3dbc64c82fda8f0271d617ab4f744f22
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 646265
Reviewed-on: https://chromium-review.googlesource.com/576350
Reviewed-by: Alex Mineer <amineer@chromium.org>
Cr-Commit-Position: refs/branch-heads/3112@{#637}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
[delete] https://crrev.com/e770fc795d946811a5e2cd91224d6065de48527e/third_party/WebKit/LayoutTests/virtual/stable/animations-unprefixed/frames-timing-function.html
[modify] https://crrev.com/fd23350d864d212a74bbcfa17a91a96dc4991810/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h
[modify] https://crrev.com/fd23350d864d212a74bbcfa17a91a96dc4991810/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/fd23350d864d212a74bbcfa17a91a96dc4991810/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
[modify] https://crrev.com/fd23350d864d212a74bbcfa17a91a96dc4991810/third_party/WebKit/Source/platform/animation/TimingFunction.h
[modify] https://crrev.com/fd23350d864d212a74bbcfa17a91a96dc4991810/third_party/WebKit/Source/platform/animation/TimingFunctionTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e0767c297e00dfc1793513d096eb07f4382864f1

commit e0767c297e00dfc1793513d096eb07f4382864f1
Author: Nate Chapin <japhet@chromium.org>
Date: Tue Jul 18 21:00:11 2017

Reland "Unship frames() animation timing function"

This patch unships the frames() animation timing function due to
unresolved issues over the naming.

No intent is required as the timing function has not reached the
stable channel of Chrome yet.

Ongoing spec discussion:
https://github.com/w3c/csswg-drafts/issues/1301

TBR=alancutter@chromium.org,amineer@chromium.org

Bug: 646265

This reverts commit fd23350d864d212a74bbcfa17a91a96dc4991810, and fixes
RuntimeEnabledFeatures callers to use pre-blink reformat function naming.

Change-Id: Ic9ff40caa6a32fb11063fcfa5b06f789f40da67e
Reviewed-on: https://chromium-review.googlesource.com/576201
Reviewed-by: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/branch-heads/3112@{#640}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}
[add] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/LayoutTests/virtual/stable/animations-unprefixed/frames-timing-function.html
[modify] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/Source/core/css/CSSTimingFunctionValue.h
[modify] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
[modify] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/Source/platform/animation/TimingFunction.h
[modify] https://crrev.com/e0767c297e00dfc1793513d096eb07f4382864f1/third_party/WebKit/Source/platform/animation/TimingFunctionTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/57e50a85c23ba330bf13e10cb092acc9507d87bf

commit 57e50a85c23ba330bf13e10cb092acc9507d87bf
Author: Alan Cutter <alancutter@chromium.org>
Date: Mon Feb 12 01:22:04 2018

Update step-middle deprecation message to not mention frames()

frames() is no longer being shipped in M60 [0], as a result we cannot refer
to it as a replacement for step-middle.

[0] https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/j7l8_DjMsVE/0HKZgZXNAQAJ

Bug: 646265
Change-Id: I8f828fabd7c6c8ccc5e72d393ef260de31fcb23c
Reviewed-on: https://chromium-review.googlesource.com/557481
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Suzy Howlett <suzyh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#536017}
[modify] https://crrev.com/57e50a85c23ba330bf13e10cb092acc9507d87bf/third_party/WebKit/LayoutTests/animations/usecounters/step-middle-keyword-timing-function-deprecated-expected.txt
[modify] https://crrev.com/57e50a85c23ba330bf13e10cb092acc9507d87bf/third_party/WebKit/LayoutTests/animations/usecounters/step-middle-timing-function-deprecated-expected.txt
[modify] https://crrev.com/57e50a85c23ba330bf13e10cb092acc9507d87bf/third_party/WebKit/Source/core/frame/Deprecation.cpp