Create a RegisterViewAssociate method in ViewManager

mojo/tools/data/apptests

 # This file contains a list of Mojo apptests. For description of the file
 # format, see `mojo_test` in devtools.
 
 tests = [
   {
     "test": "mojo:asset_bundle_apptests",
   },
   {
     "test": "mojo:authenticating_url_loader_interceptor_apptests",
   },
@@ skipping 46 matching lines @@
     "test": "mojo:prediction_apptests",
   },
   {
     "test": "mojo:ui_apptests",
     "shell-args": ["--args-for=mojo:native_viewport_service --use-headless-config --use-osmesa"],
   },
   {
     "test": "mojo:ui_associates_apptests",
   },
   {
+    "test": "mojo:view_manager_apptests",
+  },
+  {
     "test": "mojo:url_response_disk_cache_apptests",
   },
   {
     "test": "mojo:versioning_apptests",
   },
   {
     "test": "mojo:platform_handle_private_apptests",
   },
   {
     "test": "mojo:image_pipe_apptests",
@@ skipping 63 matching lines @@
       # These tests rely on various things in /bin.
       "test": "mojo:native_support_apptests",
     },
     {
       # https://github.com/domokit/mojo/issues/61
       # Sometime the shell get a trucated application when exposed through the
       # http server.
       "test": "mojo:shell_apptests",
     },
   ]