Adding histograms showing fraction of page load times

net/url_request/url_request_job.h

Index: net/url_request/url_request_job.h
===================================================================
--- net/url_request/url_request_job.h	(revision 147972)
+++ net/url_request/url_request_job.h	(working copy)
@@ -286,6 +286,9 @@
   // Set the status of the job.
   void SetStatus(const URLRequestStatus& status);
 
+  // Custom handler for derived classes when the request is detached.
+  virtual void OnDetachRequest() {}
+
   // The number of bytes read before passing to the filter.
   int prefilter_bytes_read() const { return prefilter_bytes_read_; }