Fix misspelling in 'Unsafe WebGPU' flag description

"sanboxing" should be spelled "sandboxing".

Change-Id: Iaa82f4bae962456b072268028fd1a578591b7f65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1975298Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Rafael Cintron <rafael.cintron@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#726254}

chrome/browser/flag_descriptions.cc

@@ -2223,7 +2223,7 @@ const char kUnexpireFlagsM80Description[] =
 
 const char kUnsafeWebGPUName[] = "Unsafe WebGPU";
 const char kUnsafeWebGPUDescription[] =
-    "Enables access to the experimental WebGPU API. Warning: As GPU sanboxing "
+    "Enables access to the experimental WebGPU API. Warning: As GPU sandboxing "
     "isn't implemented yet for the WebGPU API, it is possible to read GPU data "
     "for other processes.";