Sync the browser test host resolver with the network process before a test runs.

content/public/app/mojo/content_browser_manifest.json

 {
   "name": "content_browser",
   "display_name": "Content (browser process)",
   "interface_provider_specs": {
     "service_manager:connector": {
       "provides": {
         "gpu": [
           "content::mojom::FieldTrialRecorder",
           "media::mojom::AndroidOverlayProvider",
           "memory_instrumentation::mojom::Coordinator"
@@ skipping 44 matching lines @@
         // In classic ash, the browser supplies ash interfaces to itself.
         "content_browser": [ "ash" ],
         "content_gpu": [ "browser" ],
         "content_plugin": [ "browser" ],
         "content_renderer": [ "browser" ],
         "content_utility": [ "browser" ],
         "data_decoder": [ "image_decoder" ],
         "device": [ "device:wake_lock" ],
         "file": [ "file:filesystem", "file:leveldb" ],
         "media": [ "media:media" ],
-        "network": [ "url_loader" ],
+        "network": [
+          "test",
+          "url_loader"
+        ],
         "ui": [ "display_output_protection" ],
         "service_manager": [
           "service_manager:client_process",
           "service_manager:instance_name",
           "service_manager:user_id"
         ],
         "shape_detection": [
           "barcode_detection",
           "face_detection",
           "text_detection"
@@ skipping 29 matching lines @@
           "payments::mojom::PaymentRequest",
           "ui::mojom::Gpu"
         ]
       },
       "requires": {
         "content_renderer": [ "browser" ]
       }
     }
   }
 }