Modify extension request IPC messages to pass a ListValue instead of a string.

chrome/browser/tab_contents/tab_contents.cc

Index: chrome/browser/tab_contents/tab_contents.cc
diff --git a/chrome/browser/tab_contents/tab_contents.cc b/chrome/browser/tab_contents/tab_contents.cc
index f220074edb0f9c879fc727bdc546db947de26813..6020d60a79b9e58a0676fc78bede5f905dd37dc2 100644
--- a/chrome/browser/tab_contents/tab_contents.cc
+++ b/chrome/browser/tab_contents/tab_contents.cc
@@ -2208,7 +2208,7 @@ void TabContents::DomOperationResponse(const std::string& json_string,
 }
 
 void TabContents::ProcessDOMUIMessage(const std::string& message,
-                                      const std::string& content,
+                                      const Value* content,
                                       int request_id,
                                       bool has_callback) {
   if (!render_manager_.dom_ui()) {