From a37e4a68351b86e0f316e7b9ac75b06de92f4037 Mon Sep 17 00:00:00 2001
From: Chris Mills <chrisdavidmills@gmail.com>
Date: Mon, 29 Jun 2026 14:04:31 +0100
Subject: [PATCH] Add pref info to responsive iframe sizing data

---
 api/Window.json                  |  8 +++++-
 css/properties/frame-sizing.json | 48 ++++++++++++++++++++++++++++----
 html/elements/meta.json          |  8 +++++-
 3 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/api/Window.json b/api/Window.json
index d54942f96a127a..0d5e6cf78f4e69 100644
--- a/api/Window.json
+++ b/api/Window.json
@@ -5137,7 +5137,13 @@
           "spec_url": "https://drafts.csswg.org/css-sizing-4/#dom-window-requestresize",
           "support": {
             "chrome": {
-              "version_added": "preview"
+              "version_added": "149",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "#enable-experimental-web-platform-features"
+                }
+              ]
             },
             "chrome_android": "mirror",
             "edge": "mirror",
diff --git a/css/properties/frame-sizing.json b/css/properties/frame-sizing.json
index 0fde4f49e1a432..d87f4d304c774d 100644
--- a/css/properties/frame-sizing.json
+++ b/css/properties/frame-sizing.json
@@ -6,7 +6,13 @@
           "spec_url": "https://drafts.csswg.org/css-sizing-4/#responsive-iframes",
           "support": {
             "chrome": {
-              "version_added": "preview"
+              "version_added": "149",
+              "flags": [
+                {
+                  "type": "preference",
+                  "name": "#enable-experimental-web-platform-features"
+                }
+              ]
             },
             "chrome_android": "mirror",
             "edge": "mirror",
@@ -36,7 +42,13 @@
             "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-auto",
             "support": {
               "chrome": {
-                "version_added": "preview"
+                "version_added": "149",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "#enable-experimental-web-platform-features"
+                  }
+                ]
               },
               "chrome_android": "mirror",
               "edge": "mirror",
@@ -67,7 +79,13 @@
             "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-block-size",
             "support": {
               "chrome": {
-                "version_added": "preview"
+                "version_added": "149",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "#enable-experimental-web-platform-features"
+                  }
+                ]
               },
               "chrome_android": "mirror",
               "edge": "mirror",
@@ -98,7 +116,13 @@
             "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-height",
             "support": {
               "chrome": {
-                "version_added": "preview"
+                "version_added": "149",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "#enable-experimental-web-platform-features"
+                  }
+                ]
               },
               "chrome_android": "mirror",
               "edge": "mirror",
@@ -129,7 +153,13 @@
             "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-inline-size",
             "support": {
               "chrome": {
-                "version_added": "preview"
+                "version_added": "149",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "#enable-experimental-web-platform-features"
+                  }
+                ]
               },
               "chrome_android": "mirror",
               "edge": "mirror",
@@ -160,7 +190,13 @@
             "spec_url": "https://drafts.csswg.org/css-sizing-4/#valdef-frame-sizing-content-width",
             "support": {
               "chrome": {
-                "version_added": "preview"
+                "version_added": "149",
+                "flags": [
+                  {
+                    "type": "preference",
+                    "name": "#enable-experimental-web-platform-features"
+                  }
+                ]
               },
               "chrome_android": "mirror",
               "edge": "mirror",
diff --git a/html/elements/meta.json b/html/elements/meta.json
index f2817dac3d9d67..3515dc86b0e368 100644
--- a/html/elements/meta.json
+++ b/html/elements/meta.json
@@ -503,7 +503,13 @@
               ],
               "support": {
                 "chrome": {
-                  "version_added": "preview"
+                  "version_added": "149",
+                  "flags": [
+                    {
+                      "type": "preference",
+                      "name": "#enable-experimental-web-platform-features"
+                    }
+                  ]
                 },
                 "chrome_android": "mirror",
                 "edge": "mirror",