Moved NavigationManagerImpl serialization out of CRWSessionController.

ios/web/navigation/navigation_manager_impl.h

Index: ios/web/navigation/navigation_manager_impl.h
diff --git a/ios/web/navigation/navigation_manager_impl.h b/ios/web/navigation/navigation_manager_impl.h
index ef09e5205d991ceaf33001fdb9bf2da2b2eb4ee6..0df7fea8c59d7c3aae3e13695399d5712611607c 100644
--- a/ios/web/navigation/navigation_manager_impl.h
+++ b/ios/web/navigation/navigation_manager_impl.h
@@ -23,15 +23,19 @@ class NavigationItem;
 struct Referrer;
 class NavigationManagerDelegate;
 class NavigationManagerFacadeDelegate;
+class SerializedNavigationManagerBuilder;
 
 // Implementation of NavigationManager.
 // Generally mirrors upstream's NavigationController.
 class NavigationManagerImpl : public NavigationManager {
  public:
-  NavigationManagerImpl(NavigationManagerDelegate* delegate,
-                        BrowserState* browser_state);
+  NavigationManagerImpl();
   ~NavigationManagerImpl() override;
 
+  // Setters for NavigationManagerDelegate and BrowserState.
+  void SetDelegate(NavigationManagerDelegate* delegate);
+  void SetBrowserState(BrowserState* browser_state);
+
   // Sets the CRWSessionController that backs this object.
   // Keeps a strong reference to |session_controller|.
   // This method should only be called when deserializing |session_controller|
@@ -58,6 +62,10 @@ class NavigationManagerImpl : public NavigationManager {
   void ReplaceSessionHistory(ScopedVector<NavigationItem> items,
                              int current_index);
 
+  // Returns a deep copy of the NavigationManager for use in serialization.
+  // Does not copy |delegate_| or |facade_delegate_|.
+  scoped_ptr<NavigationManagerImpl> CopyForSerialization() const;
+
   // Sets the delegate used to drive the navigation controller facade.
   void SetFacadeDelegate(NavigationManagerFacadeDelegate* facade_delegate);
   NavigationManagerFacadeDelegate* GetFacadeDelegate() const;
@@ -130,6 +138,8 @@ class NavigationManagerImpl : public NavigationManager {
   // CRWSessionController.
   void CopyState(NavigationManagerImpl* navigation_manager);
  private:
+  friend SerializedNavigationManagerBuilder;
+
   // The primary delegate for this manager.
   NavigationManagerDelegate* delegate_;