Revert of Moved NavigationManagerImpl serialization out of CRWSessionController.

ios/web/navigation/navigation_manager_impl.mm

Index: ios/web/navigation/navigation_manager_impl.mm
diff --git a/ios/web/navigation/navigation_manager_impl.mm b/ios/web/navigation/navigation_manager_impl.mm
index 31a3377b3ade1cfd36a29384fade3e5df96e02c6..6d7835c92d4c47ab694a11b77e8198b34d45afa2 100644
--- a/ios/web/navigation/navigation_manager_impl.mm
+++ b/ios/web/navigation/navigation_manager_impl.mm
@@ -70,22 +70,20 @@
   return *this;
 }
 
-NavigationManagerImpl::NavigationManagerImpl()
-    : delegate_(nullptr), browser_state_(nullptr), facade_delegate_(nullptr) {}
+NavigationManagerImpl::NavigationManagerImpl(
+    NavigationManagerDelegate* delegate,
+    BrowserState* browser_state)
+    : delegate_(delegate),
+      browser_state_(browser_state),
+      facade_delegate_(nullptr) {
+  DCHECK(browser_state_);
+}
 
 NavigationManagerImpl::~NavigationManagerImpl() {
   // The facade layer should be deleted before this object.
   DCHECK(!facade_delegate_);
 
   [session_controller_ setNavigationManager:nullptr];
-}
-
-void NavigationManagerImpl::SetDelegate(NavigationManagerDelegate* delegate) {
-  delegate_ = delegate;
-}
-
-void NavigationManagerImpl::SetBrowserState(BrowserState* browser_state) {
-  browser_state_ = browser_state;
 }
 
 void NavigationManagerImpl::SetSessionController(