[ozone/wayland] avoid code with side effects inside DCHECK()

Don't call surfaces_.erase() inside DCHECK(). Otherwise this is not
executed when chromium is built without DCHECK. As a result deleted
surfaces may be accessed.
Call surfaces_.erase() unconditionally and only check the return value to
fix this.

Bug: 1006813
Change-Id: Id8f280afd0f92770dda1b7b66b892343d6939c02
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1845755Reviewed-by: Maksim Sisov <msisov@igalia.com>
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Cr-Commit-Position: refs/heads/master@{#703656}

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

@@ -515,7 +515,8 @@ void WaylandBufferManagerHost::OnWindowAdded(WaylandWindow* window) {
 
 void WaylandBufferManagerHost::OnWindowRemoved(WaylandWindow* window) {
   DCHECK(window);
-  DCHECK(surfaces_.erase(window->GetWidget()));
+  auto ret = surfaces_.erase(window->GetWidget());
+  DCHECK(ret);
 }
 
 void WaylandBufferManagerHost::SetTerminateGpuCallback(