Implement CreateBufferMapped in dawn_wire

Bug: dawn:7
Change-Id: I7112c87c3b671cd7a7774af7f3a094a189f2b4b0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7402
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/dawn_wire.json b/dawn_wire.json
index 02338b4..fb7f979 100644
--- a/dawn_wire.json
+++ b/dawn_wire.json
@@ -25,6 +25,11 @@
             { "name": "data length", "type": "uint32_t" },
             { "name": "data", "type": "uint8_t", "annotation": "const*", "length": "data length" }
         ],
+        "device create buffer mapped": [
+            { "name": "device", "type": "device" },
+            { "name": "descriptor", "type": "buffer descriptor", "annotation": "const*" },
+            { "name": "result", "type": "ObjectHandle", "handle_type": "buffer" }
+        ],
         "destroy object": [
             { "name": "object type", "type": "ObjectType" },
             { "name": "object id", "type": "ObjectId" }