Rip out browser-side RID caching for most visited items.

chrome/browser/ui/webui/ntp/thumbnail_source.h

Index: chrome/browser/ui/webui/ntp/thumbnail_source.h
diff --git a/chrome/browser/ui/webui/ntp/thumbnail_source.h b/chrome/browser/ui/webui/ntp/thumbnail_source.h
index 09be5bee66abe13ddb1bed2067408bb8fe3ac088..80084079bc0ff23ae4760f8b20826f861c564cb6 100644
--- a/chrome/browser/ui/webui/ntp/thumbnail_source.h
+++ b/chrome/browser/ui/webui/ntp/thumbnail_source.h
@@ -5,7 +5,6 @@
 #ifndef CHROME_BROWSER_UI_WEBUI_NTP_THUMBNAIL_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_THUMBNAIL_SOURCE_H_
 
-#include <map>
 #include <string>
 
 #include "base/basictypes.h"
@@ -51,14 +50,6 @@ class ThumbnailSource : public content::URLDataSource {
   // ThumbnailService.
   scoped_refptr<thumbnails::ThumbnailService> thumbnail_service_;
 
-  // Transient mappings from an ID-based path to an URL-based path.
-  // The key is an ID-string, the value is a URL string.
-  // Mappings are added in ShouldServiceRequest() and erased once
-  // the request is serviced in StartDataRequest().
-  // TODO(dhollowa): Consider passing the |request| object through
-  // to the StartDataRequest() call.
-  mutable std::map<std::string, std::string> id_to_url_map_;
-
   // Only used when servicing requests on the UI thread.
   Profile* const profile_;