[WebExtensions] Deprecate runtime.PlatformInfo.nacl_arch by bershanskiy · Pull Request #43799 · mdn/content

bershanskiy · 2026-04-15T15:55:17Z

Description

Chromium is the only engine which supported Google Native Client (NaCl) and runtime.PlatformInfo.nacl_arch WebExtension API. Chromium removed NaCl and is currently in the process of removal of associated WebExtension API remnants.

Motivation

Update MDN in line with Chromium development.

Additional details

Google Chrome deprecated runtime.PlatformInfo.nacl_arch and runtime.PlatformNaclArch. Google plans to run an experiment removing nacl_arch from runtime.getPlatformInfo() and we would like to increase awareness of this deprecation. Hardcoded constant enum runtime.PlatformNaclArch is not part of this experiment, but will be removed shortly after runtime.PlatformInfo.nacl_arch removal.

Details:
chromium/chromium@913e0c0
chromium/chromium@6e62e12
chromium/chromium@9b22796

Related issues and pull requests

I will prepare BCD PR shortly.

CC @oliverdunk

github-actions · 2026-04-15T15:56:57Z

Preview URLs (3 pages)

(comment last updated: 2026-04-19 16:52:08)

rebloor

@bershanskiy some type of fixes and other suggestions for your consideration

rebloor · 2026-04-16T17:15:45Z

-Values of this type are strings. Possible values are: `"arm"`, `"x86-32"`, `"x86-64"`.
+{{Deprecated_Header}}{{non-standard_header}}
+
+The enumerated value representing CPU instruction set architecture of Google Native Client used by the browser. This enum is deprecated, following removal of Google Native Client from Google Chrome. As of 2026, Chromium intends to remove this enum. Consider migrating to `PlatformArch` also available in {{WebExtAPIRef("runtime.PlatformInfo")}} via {{WebExtAPIRef("runtime.getPlatformInfo()")}}.


Suggested change

The enumerated value representing CPU instruction set architecture of Google Native Client used by the browser. This enum is deprecated, following removal of Google Native Client from Google Chrome. As of 2026, Chromium intends to remove this enum. Consider migrating to `PlatformArch` also available in {{WebExtAPIRef("runtime.PlatformInfo")}} via {{WebExtAPIRef("runtime.getPlatformInfo()")}}.

The enumerated value representing the CPU instruction set architecture of Google Native Client used by the browser. This enum is deprecated, following the removal of Google Native Client from Google Chrome. As of 2026, Chromium intends to remove this enum. Consider migrating to {{WebExtAPIRef("runtime.PlatformArch")}} in {{WebExtAPIRef("runtime.PlatformInfo")}} which you obtain using {{WebExtAPIRef("runtime.getPlatformInfo()")}}.

Both PlatformArch and PlatformNaclArch are available via the same API runtime.getPlatformInfo(), but the edit appears to suggest otherwise:

Consider migrating to {{WebExtAPIRef("runtime.PlatformArch")}} in {{WebExtAPIRef("runtime.PlatformInfo")}} which you obtain using {{WebExtAPIRef("runtime.getPlatformInfo()")}}.

rebloor · 2026-04-16T17:42:12Z

+- `ARM`
+  - : The string literal `"arm"`. Represents all versions of ARM ISA, including all 32-bit and 64-bit variants. Equivalent to `PlatformArch.ARM` (32-bit variant) and `PlatformArch.ARM64` combined into one value.
+- `X86_32`
+  - : The string literal `"x86-32"`. Represents 32-bit variant of the x86 arhitecture. Equivalent to `PlatformArch.X86_32`.
+- `X86_64`
+  - : The string literal `"x86-64"`. Represents 64-bit-compatiable variant of the x86 arhitecture. Equivalent to `PlatformArch.X86_64`.
+- `MIPS`
+  - : The string literal `"mips"`. Represents 32-bit variant of MIPS ISA, which was never officially supported by official releases. Equivalent to `PlatformArch.MIPS`.
+- `MIPS64`
+  - : The string literal `"mips64"`. Represents 64-bit variant of MIPS ISA, which was never officially supported by official releases. Equivalent to `PlatformArch.MIPS64`.


The Chrome documentation includes values not included in the MDN documanation (e.g., arm64, mips can we update that here and add to the BCD update? Also, all values are stated as lowercase in the documentation.

Suggested change

- `ARM`

- : The string literal `"arm"`. Represents all versions of ARM ISA, including all 32-bit and 64-bit variants. Equivalent to `PlatformArch.ARM` (32-bit variant) and `PlatformArch.ARM64` combined into one value.

- `X86_32`

- : The string literal `"x86-32"`. Represents 32-bit variant of the x86 arhitecture. Equivalent to `PlatformArch.X86_32`.

- `X86_64`

- : The string literal `"x86-64"`. Represents 64-bit-compatiable variant of the x86 arhitecture. Equivalent to `PlatformArch.X86_64`.

- `MIPS`

- : The string literal `"mips"`. Represents 32-bit variant of MIPS ISA, which was never officially supported by official releases. Equivalent to `PlatformArch.MIPS`.

- `MIPS64`

- : The string literal `"mips64"`. Represents 64-bit variant of MIPS ISA, which was never officially supported by official releases. Equivalent to `PlatformArch.MIPS64`.

- `ARM`

- : The string literal `"arm"`. Represents all versions of the ARM ISA, including all 32-bit and 64-bit variants. Equivalent to [`PlatformArch.arm`](/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/PlatformArch#arm) (32-bit variant) and `PlatformArch.arm64` combined into one value.

- `X86_32`

- : The string literal `"x86-32"`. Represents the 32-bit variant of the x86 architecture. Equivalent to [`PlatformArch.x86_32`](/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/PlatformArch#x86-32) .

- `X86_64`

- : The string literal `"x86-64"`. Represents the 64-bit variant of the x86 architecture. Equivalent to [`PlatformArch.x86_64`](/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/PlatformArch#x86-64).

- `MIPS`

- : The string literal `"mips"`. Represents the 32-bit variant of the MIPS ISA, which was never supported by official releases. Equivalent to `PlatformArch.mips`.

- `MIPS64`

- : The string literal `"mips64"`. Represents the 64-bit variant of the MIPS ISA, which was never supported by official releases. Equivalent to `PlatformArch.mips64`.

Copied your version and just removed extra space at the end of description for x86-64.

The Chrome documentation includes values not included in the MDN documanation

Chromium specifies that chrome.runtime.PlatformNaclArch has value {ARM: 'arm', MIPS: 'mips', MIPS64: 'mips64', X86_32: 'x86-32', X86_64: 'x86-64'}, we already updated this document accordingly. Or did you mean that we should also update document about chrome.runtime.PlatformArch?

@bershanskiy, sorry for not being clear about the missing documentation. I was referring to the MDN page (https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/PlatformArch). So you make the comment "Equivalent to PlatformArch.mips." but the corresponding page on MDN doesn't document mips.

This is an interesting point. We can trivially document Chromium behavior for runtime.PlatformNaclArch because the other two engines (Firefox, WebKit) omit it. This is not the case with runtime.PlatformArch. Unfortunately, all three main engines disagree on both keys and values in runtime.PlatformArch.

Here are outputs of JSON.stringify(chrome.runtime.PlatformArch, null, 2) on different browsers:

Google Chrome (matches the source)

{ "ARM": "arm", "ARM64": "arm64", "MIPS": "mips", "MIPS64": "mips64", "RISCV64": "riscv64", "X86_32": "x86-32", "X86_64": "x86-64" }

Firefox (source specifies only values and keys are auto-generated):

{ "AARCH64": "aarch64", "ARM": "arm", "PPC64": "ppc64", "RISCV64": "riscv64", "S390X": "s390x", "SPARC64": "sparc64", "X86-32": "x86-32", "X86-64": "x86-64", "NOARCH": "noarch" }

At the moment, I don't have access to my Safari machine, but I remember it being different from both Chrome and Firefox in some yet another way.

@bershanskiy, still investigating but have opened a couple of draft PR:

Add missing PlatformArch values Add missing PlatformArch values #43847

PlatformArch values support details Update to Window.showSaveFilePicker() #29512

Please feel free to comment if necessary.

oliverdunk · 2026-04-17T10:53:58Z

Thanks all! This is generally looking good, happy to do a final review once the suggested changes have been incorporated.

rebloor

@bershanskiy a couple of suggestions regarding the deprecation notice and info about the "replacement"

Chromium is the only engine which supported Google Native Client (NaCl) and runtime.PlatformInfo.nacl_arch WebExtension API. Chromium removed NaCl and is currently in the process of removal of associated WebExtensions API remnants. Details: chromium/chromium@913e0c0 chromium/chromium@6e62e12 chromium/chromium@9b22796

rebloor

Thanks @bershanskiy

bershanskiy requested a review from a team as a code owner April 15, 2026 15:55

bershanskiy requested review from willdurand and removed request for a team April 15, 2026 15:55

github-actions Bot added Content:WebExt WebExtensions docs size/s [PR only] 6-50 LoC changed labels Apr 15, 2026

bershanskiy mentioned this pull request Apr 16, 2026

[WebExtensions] Deprecate Native Client info in runtime API mdn/browser-compat-data#29491

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rebloor requested changes Apr 16, 2026

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bershanskiy force-pushed the nacl_arch branch 3 times, most recently from ca9b0d1 to 6a6b544 Compare April 17, 2026 13:21

rebloor requested changes Apr 17, 2026

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Comment thread files/en-us/mozilla/add-ons/webextensions/api/runtime/platformnaclarch/index.md Outdated

Comment thread files/en-us/mozilla/add-ons/webextensions/api/runtime/platformnaclarch/index.md Outdated

bershanskiy force-pushed the nacl_arch branch from 6a6b544 to a362dce Compare April 18, 2026 08:39

bershanskiy requested a review from rebloor April 18, 2026 08:41

Revert to usual section title

783d1b9

rebloor approved these changes Apr 19, 2026

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rebloor merged commit d093679 into mdn:main Apr 19, 2026
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This was referenced Apr 19, 2026

Add missing PlatformArch values #43847

Draft

PlatformArch values support details mdn/browser-compat-data#29512

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bershanskiy commented Apr 15, 2026

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oliverdunk commented Apr 17, 2026

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