[ozone/wayland] Remove unused function.

Bug: None
Test: compiles
Change-Id: I28b4396fc0703451b5c4aa91365db1e5f2e45d80
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2368799
Commit-Queue: Eliot Courtney <edcourtney@chromium.org>
Reviewed-by: Maksim Sisov (GMT+3) <msisov@igalia.com>
Reviewed-by: Robert Kroeger <rjkroege@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800933}

ui/ozone/platform/wayland/host/wayland_buffer_manager_host.cc

@@ -100,12 +100,6 @@ class WaylandBufferManagerHost::Surface {
     return true;
   }
 
-  bool CreateBuffer(const gfx::Size& size, uint32_t buffer_id) {
-    auto result = buffers_.emplace(
-        buffer_id, std::make_unique<WaylandBuffer>(size, buffer_id));
-    return result.second;
-  }
-
   size_t DestroyBuffer(uint32_t buffer_id) {
     auto* buffer = GetBuffer(buffer_id);