Add mimetypes on the "chrome-resource://" responses....

chrome/browser/browser_about_handler.cc

Index: chrome/browser/browser_about_handler.cc
===================================================================
--- chrome/browser/browser_about_handler.cc	(revision 5286)
+++ chrome/browser/browser_about_handler.cc	(working copy)
@@ -70,6 +70,10 @@
   // the path we registered.
   virtual void StartDataRequest(const std::string& path, int request_id);
 
+  virtual std::string GetMimeType(const std::string&) const {
+    return "text/html";
+  }
+
   // Send the response data.
   void FinishDataRequest(const std::string& html, int request_id);