Use the serviceworker with mojo by default

third_party/WebKit/LayoutTests/VirtualTestSuites

 [
   {
     "prefix": "gpu",
     "base": "fast/canvas",
     "args": ["--enable-accelerated-2d-canvas",
              "--disable-display-list-2d-canvas"]
   },
   {
     "prefix": "display_list_2d_canvas",
     "base": "fast/canvas",
@@ skipping 267 matching lines @@
     "prefix": "scalefactor150",
     "base": "fast/events/synthetic-events",
     "args": ["--force-device-scale-factor=1.5"]
   },
   {
     "prefix": "enable_wasm",
     "base": "http/tests/wasm",
     "args": ["--enable-features=WebAssembly"]
   },
   {
-    "prefix": "mojo-service-worker",
+    "prefix": "disable-mojo-service-worker",
     "base": "http/tests/serviceworker",
-    "args": ["--mojo-service-worker"]
+    "args": ["--disable-mojo-service-worker"]
   },
   {
     "prefix": "service-worker-navigation-preload",
     "base": "http/tests/serviceworker",
     "args": ["--enable-features=ServiceWorkerNavigationPreload"]
   },
   {
     "prefix": "layout_ng",
     "base": "fast/block/basic",
     "args": ["--enable-blink-features=LayoutNG"]
   },
   {
     "prefix": "layout_ng",
     "base": "fast/block/margin-collapse",
     "args": ["--enable-blink-features=LayoutNG"]
   },
   {
     "prefix": "layout_ng",
     "base": "fast/block/float",
     "args": ["--enable-blink-features=LayoutNG"]
   }
 ]