Increase test coverage for Navigation.MainFrameSchemeDifferentPage

components/navigation_metrics/BUILD.gn

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 static_library("navigation_metrics") {
   sources = [
     "navigation_metrics.cc",
     "navigation_metrics.h",
     "origins_seen_service.cc",
     "origins_seen_service.h",
   ]
 
   deps = [
     "//base",
     "//components/keyed_service/core",
     "//url",
   ]
 }
+
+source_set("unit_tests") {
+  testonly = true
+  sources = [
+    "navigation_metrics_unittest.cc",
+  ]
+  deps = [
+    ":navigation_metrics",
+    "//base/test:test_support",
+    "//testing/gtest",
+    "//url",
+  ]
+}