Implemented WebStateObserver::DidFinishNavigation(NavigationHandle*).

ios/web/BUILD.gn

Index: ios/web/BUILD.gn
diff --git a/ios/web/BUILD.gn b/ios/web/BUILD.gn
index 322051cfef5b69c511d3aa6aff292de03ec43b49..ed16f341d8c3050ed4aae5526cd6286275ff54ff 100644
--- a/ios/web/BUILD.gn
+++ b/ios/web/BUILD.gn
@@ -151,6 +151,7 @@ source_set("web_arc") {
     "public/web_state/js/crw_js_injection_evaluator.h",
     "public/web_state/js/crw_js_injection_manager.h",
     "public/web_state/js/crw_js_injection_receiver.h",
+    "public/web_state/navigation_handle.h",
     "public/web_state/page_display_state.h",
     "public/web_state/page_display_state.mm",
     "public/web_state/ui/crw_content_view.h",
@@ -208,6 +209,8 @@ source_set("web_arc") {
     "web_state/js/crw_js_window_id_manager.mm",
     "web_state/js/page_script_util.h",
     "web_state/js/page_script_util.mm",
+    "web_state/navigation_handle_impl.h",
+    "web_state/navigation_handle_impl.mm",
     "web_state/page_viewport_state.h",
     "web_state/page_viewport_state.mm",
     "web_state/ui/crw_context_menu_controller.h",
@@ -564,6 +567,7 @@ test("ios_web_unittests") {
     "web_state/js/crw_js_post_request_loader_unittest.mm",
     "web_state/js/crw_js_window_id_manager_unittest.mm",
     "web_state/js/page_script_util_unittest.mm",
+    "web_state/navigation_handle_impl_unittest.mm",
     "web_state/page_display_state_unittest.mm",
     "web_state/ui/crw_web_controller_container_view_unittest.mm",
     "web_state/ui/crw_web_controller_observer_unittest.mm",
@@ -609,6 +613,7 @@ test("ios_web_inttests") {
     "public/test/http_server_inttest.mm",
     "test/run_all_unittests.cc",
     "web_state/http_auth_inttest.mm",
+    "web_state/navigation_callbacks_inttest.mm",
     "webui/web_ui_mojo_inttest.mm",
   ]