Abstract WebContents/NavigationController from core TabRestore code

components/sessions/BUILD.gn

Index: components/sessions/BUILD.gn
diff --git a/components/sessions/BUILD.gn b/components/sessions/BUILD.gn
index f77654ed597cf264edc633090d9d3f43316a7f23..05e6bb04ed5c372d8334b33c995166d18e07abcc 100644
--- a/components/sessions/BUILD.gn
+++ b/components/sessions/BUILD.gn
@@ -12,8 +12,10 @@ config("implementation") {
 
 if (!is_ios) {
   # GYP version: components/sessions.gypi:sessions_content
-  component("sessions") {
+  source_set("sessions") {
     sources = [
+      "content/content_open_tab.cc",
+      "content/content_open_tab.h",
       "content/content_serialized_navigation_builder.cc",
       "content/content_serialized_navigation_builder.h",
       "content/content_serialized_navigation_driver.cc",
@@ -69,6 +71,7 @@ source_set("shared") {
     "base_session_service_commands.cc",
     "base_session_service_commands.h",
     "base_session_service_delegate.h",
+    "core/open_tab.h",
     "core/serialized_navigation_driver.h",
     "core/session_constants.cc",
     "core/session_constants.h",