Remove navigation_service_unittests, along with the service itself.

testing/buildbot/chromium.win.json

 {
   "Win 7 Tests x64 (1)": {
     "gtest_tests": [
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "accessibility_unittests"
       },
       {
@@ skipping 307 matching lines @@
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "native_theme_unittests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
-        "test": "navigation_unittests"
-      },
-      {
-        "swarming": {
-          "can_use_on_swarming_builders": true
-        },
         "test": "net_unittests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "pdf_unittests"
       },
       {
         "swarming": {
@@ skipping 1634 matching lines @@
     "additional_compile_targets": [
       "chrome_official_builder"
     ]
   },
   "Win8 GYP (dbg)": {
     "additional_compile_targets": [
       "all"
     ]
   }
 }