dawn.json: Use void* instead of uint8_t* for data pointers

This requires some changes in the wire because WireCmd doesn't know the
size of void. This also adds a handwritten implementation of the Wire
commands for SetSubData that internally converts to uint8_t so that
WireCmd can generate the de/serialization.

BUG=dawn:160

Change-Id: Icbf0fd7dd841639ee6f67333844e027b27a8afcc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/7780
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>

src/dawn_wire/server/ServerBuffer.cpp

@@ -78,6 +78,24 @@ namespace dawn_wire { namespace server {
         return true;
     }
 
+    bool Server::DoBufferSetSubDataInternal(ObjectId bufferId,
+                                            uint64_t start,
+                                            uint64_t offset,
+                                            const uint8_t* data) {
+        // The null object isn't valid as `self`
+        if (bufferId == 0) {
+            return false;
+        }
+
+        auto* buffer = BufferObjects().Get(bufferId);
+        if (buffer == nullptr) {
+            return false;
+        }
+
+        mProcs.bufferSetSubData(buffer->handle, start, offset, data);
+        return true;
+    }
+
     bool Server::DoBufferUpdateMappedData(ObjectId bufferId, uint32_t count, const uint8_t* data) {
         // The null object isn't valid as `self`
         if (bufferId == 0) {
@@ -89,10 +107,7 @@ namespace dawn_wire { namespace server {
             return false;
         }
 
-        if (data == nullptr) {
-            return false;
-        }
-
+        ASSERT(data != nullptr);
         memcpy(buffer->mappedData, data, count);
 
         return true;