Reapply r19950. Turns out it wasn't at fault for breaking the vista tests.

chrome/browser/dom_ui/chrome_url_data_manager.h

Index: chrome/browser/dom_ui/chrome_url_data_manager.h
diff --git a/chrome/browser/dom_ui/chrome_url_data_manager.h b/chrome/browser/dom_ui/chrome_url_data_manager.h
index f11045c1f60d7770b63acdbc2320c7dd87ad88d0..49e8fd1196106bccf0cfc847cc5c8bd3ae0b1d5d 100644
--- a/chrome/browser/dom_ui/chrome_url_data_manager.h
+++ b/chrome/browser/dom_ui/chrome_url_data_manager.h
@@ -112,6 +112,11 @@ private:
   // Remove a request from the list of pending requests.
   void RemoveRequest(URLRequestChromeJob* job);
 
+  // Returns true if the job exists in |pending_requests_|. False otherwise.
+  // Called by ~URLRequestChromeJob to verify that |pending_requests_| is kept
+  // up to date.
+  bool HasPendingJob(URLRequestChromeJob* job) const;
+
   // Sent by Request::SendResponse.
   void DataAvailable(RequestID request_id,
                      scoped_refptr<RefCountedBytes> bytes);