Moved serialization out of CRWSessionEntry.

ios/web/public/web_state/page_display_state.h

Index: ios/web/public/web_state/page_display_state.h
diff --git a/ios/web/public/web_state/page_display_state.h b/ios/web/public/web_state/page_display_state.h
index a9e8802092d56cce1ad84de47c218226f22a4a46..bb5d3385a1aaf507b353b188f3062540c314af00 100644
--- a/ios/web/public/web_state/page_display_state.h
+++ b/ios/web/public/web_state/page_display_state.h
@@ -5,6 +5,8 @@
 #ifndef IOS_WEB_PUBLIC_WEB_STATE_PAGE_DISPLAY_STATE_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_PAGE_DISPLAY_STATE_H_
 
+#import <Foundation/Foundation.h>
+
 namespace web {
 
 // Class used to represent the scrolling offset of a webview.
@@ -96,6 +98,7 @@ class PageDisplayState {
                    double minimum_zoom_scale,
                    double maximum_zoom_scale,
                    double zoom_scale);
+  PageDisplayState(NSDictionary* serialization);
   ~PageDisplayState();
 
   // PageScrollStates cannot be applied until the scroll offset and zoom scale
@@ -118,6 +121,12 @@ class PageDisplayState {
   bool operator==(const PageDisplayState& other) const;
   bool operator!=(const PageDisplayState& other) const;
 
+  // Returns a serialized representation of the PageDisplayState.
+  NSDictionary* GetSerialization() const;
+
+  // Returns a description string for the PageDisplayState.
+  NSString* GetDescription() const;
+
  private:
   // The scroll state for the page's UIScrollView.
   PageScrollState scroll_state_;