[webxr] Handle empty camera sync tokens in OpenXR and Cardboard [chromium/src : main]

[Alexander Cooper (Gerrit)]

Attention needed from Mingjing Zhang and Yong Li (xWF)

Alexander Cooper added 1 comment

Commit Message

Line 10, Patchset 1 (Latest):graphics binding is registered. On every frame, Blink automatically
populates the camera_sync_tokens list. If the camera is not accessed,

Alexander Cooper . unresolved

Can we not instead prevent this?

Open in Gerrit

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• Mingjing Zhang
• Yong Li (xWF)

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Gerrit-Project: chromium/src

Gerrit-Branch: main

Gerrit-Change-Id: I1fffd70aa67cc361f7c46cf4b1e1f7da1d872196

Gerrit-Change-Number: 7885484

Gerrit-PatchSet: 1

Gerrit-Owner: Yong Li (xWF) <yyon...@google.com>

Gerrit-Reviewer: Alexander Cooper <alco...@chromium.org>

Gerrit-Reviewer: Mingjing Zhang <mjz...@chromium.org>

Gerrit-Reviewer: Yong Li (xWF) <yyon...@google.com>

Gerrit-CC: Chromium LUCI CQ <chromiu...@luci-project-accounts.iam.gserviceaccount.com>

Gerrit-CC: chromium...@chromium.org

Gerrit-Attention: Mingjing Zhang <mjz...@chromium.org>

Gerrit-Attention: Yong Li (xWF) <yyon...@google.com>

Gerrit-Comment-Date: Fri, 29 May 2026 19:04:36 +0000

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[Mingjing Zhang (Gerrit)]

Attention needed from Yong Li (xWF)

Mingjing Zhang added 1 comment

Commit Message

Line 10, Patchset 1 (Latest):graphics binding is registered. On every frame, Blink automatically
populates the camera_sync_tokens list. If the camera is not accessed,

Alexander Cooper . unresolved

Can we not instead prevent this?

Mingjing Zhang

I think the alternative is to validate the camera SyncTokens [on the Blink side](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/xr/xr_session.cc;l=2334;drc=fcc8e2e643f4beab78d87a7a8566f0ed50332666;bpv=1;bpt=1), and not to push any empty SyncTokens into the `camera_sync_tokens` vector in the first place.

Alex, do you prefer this Blink-side solution?

Open in Gerrit

Related details

Attention is currently required from:

• Yong Li (xWF)

Submit Requirements:

• Code-Coverage
• Code-Owners
• Code-Review
• No-Unresolved-Comments
• Review-Enforcement

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Gerrit

Gerrit-MessageType: comment

Gerrit-Project: chromium/src

Gerrit-Branch: main

Gerrit-Change-Id: I1fffd70aa67cc361f7c46cf4b1e1f7da1d872196

Gerrit-Change-Number: 7885484

Gerrit-PatchSet: 1

Gerrit-Owner: Yong Li (xWF) <yyon...@google.com>

Gerrit-Reviewer: Alexander Cooper <alco...@chromium.org>

Gerrit-Reviewer: Mingjing Zhang <mjz...@chromium.org>

Gerrit-Reviewer: Yong Li (xWF) <yyon...@google.com>

Gerrit-CC: Chromium LUCI CQ <chromiu...@luci-project-accounts.iam.gserviceaccount.com>

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Gerrit-Comment-Date: Fri, 29 May 2026 19:20:50 +0000

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Comment-In-Reply-To: Alexander Cooper <alco...@chromium.org>

[Alexander Cooper (Gerrit)]

Attention needed from Yong Li (xWF)

Alexander Cooper added 1 comment

Commit Message

Line 10, Patchset 1 (Latest):graphics binding is registered. On every frame, Blink automatically
populates the camera_sync_tokens list. If the camera is not accessed,

Alexander Cooper . unresolved

Can we not instead prevent this?

Mingjing Zhang

I think the alternative is to validate the camera SyncTokens [on the Blink side](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/xr/xr_session.cc;l=2334;drc=fcc8e2e643f4beab78d87a7a8566f0ed50332666;bpv=1;bpt=1), and not to push any empty SyncTokens into the `camera_sync_tokens` vector in the first place.

Alex, do you prefer this Blink-side solution?

Alexander Cooper

Yeah, I think it's better to have a well behaved blink send only the tokens we expect

Gerrit-Comment-Date: Fri, 29 May 2026 19:23:13 +0000

Gerrit-HasComments: Yes

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Comment-In-Reply-To: Mingjing Zhang <mjz...@chromium.org>

Comment-In-Reply-To: Alexander Cooper <alco...@chromium.org>

[Mingjing Zhang (Gerrit)]

Attention needed from Yong Li (xWF)

Mingjing Zhang added 1 comment

Commit Message

Line 10, Patchset 1 (Latest):graphics binding is registered. On every frame, Blink automatically
populates the camera_sync_tokens list. If the camera is not accessed,

Alexander Cooper . unresolved

Can we not instead prevent this?

Mingjing Zhang

I think the alternative is to validate the camera SyncTokens [on the Blink side](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/xr/xr_session.cc;l=2334;drc=fcc8e2e643f4beab78d87a7a8566f0ed50332666;bpv=1;bpt=1), and not to push any empty SyncTokens into the `camera_sync_tokens` vector in the first place.

Alex, do you prefer this Blink-side solution?

Alexander Cooper

Yeah, I think it's better to have a well behaved blink send only the tokens we expect

Mingjing Zhang

Yeah I agree.

yyonglii@ Thank you for working on this fix. Could you instead move the SyncToken validation to the Blink side? Thanks.

Gerrit-Comment-Date: Fri, 29 May 2026 19:36:04 +0000