Only record the execution time during startup.

chrome/browser/history/top_sites_impl.h

Index: chrome/browser/history/top_sites_impl.h
diff --git a/chrome/browser/history/top_sites_impl.h b/chrome/browser/history/top_sites_impl.h
index 91518ec742b6ed79931882101310133b1e8b61cd..68d3d78379ee2d0415fda105afc562c7f1c3f18e 100644
--- a/chrome/browser/history/top_sites_impl.h
+++ b/chrome/browser/history/top_sites_impl.h
@@ -195,7 +195,10 @@ class TopSitesImpl : public TopSites,
   // if the list of forced URLs overflows, the oldest ones are dropped.
   // All mutations to cache_ *must* go through this. Should
   // be called from the UI thread.
-  void SetTopSites(const MostVisitedURLList& new_top_sites);
+  // The bool param is used for knowing weather this function is called during

[rkaplow, 2015/03/27 02:33:28]

whether

[yao, 2015/03/27 18:39:45]

Done.

+  // startup or not, thus histogram value could be recorded accordingly.
+  // TODO(yiyaoliu): Remove this when crbug/223430 is fixed.
+  void SetTopSites(const MostVisitedURLList& new_top_sites, bool startup);

[rkaplow, 2015/03/27 02:33:28]

it seems kind of messy to me to measure it with a bool like this.
Is it possible to just wrap the startup calls in a seperate histogram (outside
the settopsites call itself)?

[yao, 2015/03/27 18:39:45]

It's possible if we only care about execution time, but now we also record the
delta size within function settopsites. I can't think of a good way without
using an extra param. 

 
   // Returns the number of most visited results to request from history. This
   // changes depending upon how many urls have been blacklisted. Should be