Support fixed prefixes and suffixes when extracting terms from search template URLs.

components/search_engines/template_url.h

Index: components/search_engines/template_url.h
diff --git a/components/search_engines/template_url.h b/components/search_engines/template_url.h
index c62bd20bea689c4c5cf5f7561428e73efa1ef41d..10bc6d44885ea415fcfec2e64e8b24d6a15b29bd 100644
--- a/components/search_engines/template_url.h
+++ b/components/search_engines/template_url.h
@@ -467,6 +467,8 @@ class TemplateURLRef {
   mutable std::string search_term_key_;
   mutable size_t search_term_position_in_path_;
   mutable url::Parsed::ComponentType search_term_key_location_;
+  mutable std::string search_term_value_prefix_;
+  mutable std::string search_term_value_suffix_;
 
   mutable PostParams post_params_;