[Search] Store and recall search terms using NavigationEntry to improve search term extraction

content/public/browser/navigation_entry.h

Index: content/public/browser/navigation_entry.h
diff --git a/content/public/browser/navigation_entry.h b/content/public/browser/navigation_entry.h
index 63af6871b20e202b7d796960e9d298c9d86e2a35..7db903806d00af0f784fdc9bf6da199700091896 100644
--- a/content/public/browser/navigation_entry.h
+++ b/content/public/browser/navigation_entry.h
@@ -182,6 +182,11 @@ class NavigationEntry {
   // resources.
   virtual void SetCanLoadLocalResources(bool allow) = 0;
   virtual bool GetCanLoadLocalResources() const = 0;
+
+  // Set extra data on this NavigationEntry.
+  virtual void SetExtraData(const std::string& key, const string16& data) = 0;
+  virtual const bool GetExtraData(const std::string& key, string16* out_value)
+      const = 0;
 };
 
 }  // namespace content