From d7b92bee2dcf0f37137a6c9ce658c77e2a98104f Mon Sep 17 00:00:00 2001
From: Chris Mills <chrisdavidmills@gmail.com>
Date: Thu, 16 Oct 2025 14:43:31 +0100
Subject: [PATCH 1/3] Chromium 138 size requirement changes for GPUBuffers
 mapped at creation

---
 api/GPUDevice.json | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/api/GPUDevice.json b/api/GPUDevice.json
index 95edac810f819d..204933c87d42c5 100644
--- a/api/GPUDevice.json
+++ b/api/GPUDevice.json
@@ -393,6 +393,47 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "rangeerror_if_mappedatcreation_true_and_size_not_4_multiple": {
+          "__compat": {
+            "description": "`RangeError` thrown if `mappedAtCreation` is `true` and `size` is not a multiple of `4`.",
+            "tags": [
+              "web-features:webgpu"
+            ],
+            "support": {
+              "chrome": {
+                "version_added": "138",
+                "partial_implementation": true,
+                "notes": "Supported on ChromeOS, macOS, and Windows only."
+              },
+              "chrome_android": {
+                "version_added": "138"
+              },
+              "deno": {
+                "version_added": false
+              },
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": "mirror",
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
         }
       },
       "createCommandEncoder": {

From a70adad681cf20a71b88175837aa28dc95e5f9f9 Mon Sep 17 00:00:00 2001
From: Chris Mills <chrisdavidmills@gmail.com>
Date: Fri, 17 Oct 2025 13:46:52 +0100
Subject: [PATCH 2/3] Update api/GPUDevice.json

Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>
---
 api/GPUDevice.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/api/GPUDevice.json b/api/GPUDevice.json
index 204933c87d42c5..eb2e9e7420fbc6 100644
--- a/api/GPUDevice.json
+++ b/api/GPUDevice.json
@@ -394,7 +394,7 @@
             "deprecated": false
           }
         },
-        "rangeerror_if_mappedatcreation_true_and_size_not_4_multiple": {
+        "throws_RangeError_if_mappedAtCreation_and_size_not_multiple_of_4": {
           "__compat": {
             "description": "`RangeError` thrown if `mappedAtCreation` is `true` and `size` is not a multiple of `4`.",
             "tags": [

From 9c75126ec9d6b842f9c609b7c8e5d4ac3574385a Mon Sep 17 00:00:00 2001
From: Chris Mills <chrisdavidmills@gmail.com>
Date: Mon, 20 Oct 2025 13:44:43 +0100
Subject: [PATCH 3/3] Turn data point into note

---
 api/GPUDevice.json | 46 ++++------------------------------------------
 1 file changed, 4 insertions(+), 42 deletions(-)

diff --git a/api/GPUDevice.json b/api/GPUDevice.json
index eb2e9e7420fbc6..f153f50f8ed3c9 100644
--- a/api/GPUDevice.json
+++ b/api/GPUDevice.json
@@ -348,7 +348,10 @@
             "chrome": {
               "version_added": "113",
               "partial_implementation": true,
-              "notes": "Supported on ChromeOS, macOS, and Windows only."
+              "notes": [
+                "Supported on ChromeOS, macOS, and Windows only.",
+                "Before version 138, this method does not throw a `RangeError` exception when `mappedAtCreation` is true but `size` is not a multiple of 4; it generates a validation error instead."
+              ]
             },
             "chrome_android": {
               "version_added": "121"
@@ -393,47 +396,6 @@
             "standard_track": true,
             "deprecated": false
           }
-        },
-        "throws_RangeError_if_mappedAtCreation_and_size_not_multiple_of_4": {
-          "__compat": {
-            "description": "`RangeError` thrown if `mappedAtCreation` is `true` and `size` is not a multiple of `4`.",
-            "tags": [
-              "web-features:webgpu"
-            ],
-            "support": {
-              "chrome": {
-                "version_added": "138",
-                "partial_implementation": true,
-                "notes": "Supported on ChromeOS, macOS, and Windows only."
-              },
-              "chrome_android": {
-                "version_added": "138"
-              },
-              "deno": {
-                "version_added": false
-              },
-              "edge": "mirror",
-              "firefox": {
-                "version_added": false
-              },
-              "firefox_android": "mirror",
-              "oculus": "mirror",
-              "opera": "mirror",
-              "opera_android": "mirror",
-              "safari": {
-                "version_added": false
-              },
-              "safari_ios": "mirror",
-              "samsunginternet_android": "mirror",
-              "webview_android": "mirror",
-              "webview_ios": "mirror"
-            },
-            "status": {
-              "experimental": true,
-              "standard_track": true,
-              "deprecated": false
-            }
-          }
         }
       },
       "createCommandEncoder": {