Prevent bindings escalation on an existing NavigationEntry.

content/browser/web_contents/navigation_entry_impl.cc

Index: content/browser/web_contents/navigation_entry_impl.cc
diff --git a/content/browser/web_contents/navigation_entry_impl.cc b/content/browser/web_contents/navigation_entry_impl.cc
index 44dc6e593f4ebda5fcc5c3ad625f2cb1ffb591f6..ec78d07fbf93a8eb72e6380486fd309225453f52 100644
--- a/content/browser/web_contents/navigation_entry_impl.cc
+++ b/content/browser/web_contents/navigation_entry_impl.cc
@@ -20,6 +20,8 @@ static int GetUniqueIDInConstructor() {
 
 namespace content {
 
+int NavigationEntryImpl::kInvalidBindings = -1;
+
 NavigationEntry* NavigationEntry::Create() {
   return new NavigationEntryImpl();
 }
@@ -36,6 +38,7 @@ NavigationEntryImpl* NavigationEntryImpl::FromNavigationEntry(
 NavigationEntryImpl::NavigationEntryImpl()
     : unique_id_(GetUniqueIDInConstructor()),
       site_instance_(NULL),
+      bindings_(kInvalidBindings),
       page_type_(PAGE_TYPE_NORMAL),
       update_virtual_url_with_url_(false),
       page_id_(-1),
@@ -58,6 +61,7 @@ NavigationEntryImpl::NavigationEntryImpl(SiteInstanceImpl* instance,
                                          bool is_renderer_initiated)
     : unique_id_(GetUniqueIDInConstructor()),
       site_instance_(instance),
+      bindings_(kInvalidBindings),
       page_type_(PAGE_TYPE_NORMAL),
       url_(url),
       referrer_(referrer),
@@ -148,6 +152,13 @@ void NavigationEntryImpl::set_site_instance(SiteInstanceImpl* site_instance) {
   site_instance_ = site_instance;
 }
 
+void NavigationEntryImpl::SetBindings(int bindings) {
+  // Ensure this is set to a valid value, and that it stays the same once set.
+  CHECK_NE(bindings, kInvalidBindings);
+  CHECK(bindings_ == kInvalidBindings || bindings_ == bindings);
+  bindings_ = bindings;
+}
+
 const string16& NavigationEntryImpl::GetTitleForDisplay(
     const std::string& languages) const {
   // Most pages have real titles. Don't even bother caching anything if this is