Introduce NavigationSimulator to use in unit tests

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 9e50766e377bb4c28473e1dbc2be95d2d68b4b9e..de46956c68a1c066cfad839afedd8b6a0820a828 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -80,6 +80,8 @@ static_library("test_support") {
     "../public/test/mock_special_storage_policy.h",
     "../public/test/mock_storage_client.cc",
     "../public/test/mock_storage_client.h",
+    "../public/test/navigation_simulator.cc",
+    "../public/test/navigation_simulator.h",
     "../public/test/ppapi_test_utils.cc",
     "../public/test/ppapi_test_utils.h",
     "../public/test/render_view_test.cc",
@@ -176,6 +178,8 @@ static_library("test_support") {
     "mock_webblob_registry_impl.h",
     "mock_webclipboard_impl.cc",
     "mock_webclipboard_impl.h",
+    "navigation_simulator_impl.cc",
+    "navigation_simulator_impl.h",
     "net/url_request_abort_on_end_job.cc",
     "net/url_request_abort_on_end_job.h",
     "ppapi_unittest.cc",