Prevent bindings escalation on an existing NavigationEntry.

content/browser/web_contents/navigation_entry_impl.h

Index: content/browser/web_contents/navigation_entry_impl.h
diff --git a/content/browser/web_contents/navigation_entry_impl.h b/content/browser/web_contents/navigation_entry_impl.h
index c65bdb32b75a9d9dea2f212e344bb4000ae06810..9a1d6fe3e0bcb784797915c88496a2d52ed261d3 100644
--- a/content/browser/web_contents/navigation_entry_impl.h
+++ b/content/browser/web_contents/navigation_entry_impl.h
@@ -20,6 +20,9 @@ class CONTENT_EXPORT NavigationEntryImpl
  public:
   static NavigationEntryImpl* FromNavigationEntry(NavigationEntry* entry);
 
+  // The value of bindings() before it is set during commit.
+  static int kInvalidBindings;
+
   NavigationEntryImpl();
   NavigationEntryImpl(SiteInstanceImpl* instance,
                       int page_id,
@@ -91,6 +94,14 @@ class CONTENT_EXPORT NavigationEntryImpl
     return site_instance_.get();
   }
 
+  // Remember the set of bindings granted to this NavigationEntry at the time
+  // of commit, to ensure that we do not grant it additional bindings if we
+  // navigate back to it in the future.  This can only be changed once.
+  void SetBindings(int bindings);
+  int bindings() const {
+    return bindings_;
+  }
+
   void set_page_type(PageType page_type) {
     page_type_ = page_type;
   }
@@ -185,6 +196,8 @@ class CONTENT_EXPORT NavigationEntryImpl
   // See the accessors above for descriptions.
   int unique_id_;
   scoped_refptr<SiteInstanceImpl> site_instance_;
+  // TODO(creis): Persist bindings_. http://crbug.com/173672.
+  int bindings_;
   PageType page_type_;
   GURL url_;
   Referrer referrer_;