Moved NavigationManagerImpl serialization out of CRWSessionController.

ios/web/web_state/web_state_impl.h

Index: ios/web/web_state/web_state_impl.h
diff --git a/ios/web/web_state/web_state_impl.h b/ios/web/web_state/web_state_impl.h
index 9c4cfb6148d1d6d652d41f8d5b16c76bce402ac8..2644f5f03a709f73a075ed9ee9724f37dc1fe9f8 100644
--- a/ios/web/web_state/web_state_impl.h
+++ b/ios/web/web_state/web_state_impl.h
@@ -55,7 +55,12 @@ class WebUIIOS;
 //    writing them out for session saves.
 class WebStateImpl : public WebState, public NavigationManagerDelegate {
  public:
+  // Constructor for WebStateImpls created for new sessions.
   WebStateImpl(BrowserState* browser_state);
+  // Constructor for WebStatesImpls created for deserialized or copied
+  // NavigationManagerImpls.
+  WebStateImpl(BrowserState* browser_state,
+               scoped_ptr<NavigationManagerImpl> navigation_manager);
   ~WebStateImpl() override;
 
   // Sets the CRWWebController that backs this object. Typically
@@ -69,12 +74,11 @@ class WebStateImpl : public WebState, public NavigationManagerDelegate {
 
   // Returns a WebStateImpl that doesn't have a browser context, web
   // controller, or facade set, but which otherwise has the same state variables
-  // as the calling object (including copies of the NavigationManager and its
-  // attendant CRWSessionController).
+  // as the calling object (including copies of the NavigationManager).
   // TODO(marq): Revisit this function and the ownership model described above;
   // too this depends on and interacts directly with above-the-web-level
   // information.
-  WebStateImpl* CopyForSessionWindow();
+  scoped_ptr<WebStateImpl> CopyForSerialization() const;
 
   // Notifies the observers that a provisional navigation has started.
   void OnProvisionalNavigationStarted(const GURL& url);
@@ -279,7 +283,8 @@ class WebStateImpl : public WebState, public NavigationManagerDelegate {
   // The CRWWebController that backs and owns this object.
   CRWWebController* web_controller_;
 
-  NavigationManagerImpl navigation_manager_;
+  // The NavigationManagerImpl that stores session info for this WebStateImpl.
+  scoped_ptr<NavigationManagerImpl> navigation_manager_;
 
   // |web::WebUIIOS| object for the current page if it is a WebUI page that
   // uses the web-based WebUI framework, or nullptr otherwise.