Filter out redundant jumplist updates.

chrome/browser/jumplist_win.h

Index: chrome/browser/jumplist_win.h
diff --git a/chrome/browser/jumplist_win.h b/chrome/browser/jumplist_win.h
index 72b6d02a7cb1d3281ce4f45783708b318527b99c..1c69165960381c532b5a38282b80af3f973b4504 100644
--- a/chrome/browser/jumplist_win.h
+++ b/chrome/browser/jumplist_win.h
@@ -14,6 +14,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/task/cancelable_task_tracker.h"
+#include "base/timer/timer.h"
 #include "chrome/browser/jumplist_updater_win.h"
 #include "chrome/browser/prefs/incognito_mode_prefs.h"
 #include "chrome/browser/sessions/tab_restore_service.h"
@@ -125,6 +126,10 @@ class JumpList : public TabRestoreServiceObserver,
   // Helper for RunUpdate() that determines its parameters.
   void PostRunUpdate();
 
+  // Called on a timer to invoke RunUpdateOnFileThread() after requests storms
+  // have subsided.
+  void DeferredRunUpdate();
+
   // Runnable method that updates the jumplist, once all the data
   // has been fetched.
   void RunUpdateOnFileThread(
@@ -162,6 +167,9 @@ class JumpList : public TabRestoreServiceObserver,
   // protected by the list_lock_.
   ShellLinkItemList recently_closed_pages_;
 
+  // Timer for requesting delayed updates of the jumplist.
+  base::OneShotTimer<JumpList> timer_;
+
   // A list of URLs we need to retrieve their favicons,
   // protected by the list_lock_.
   typedef std::pair<std::string, scoped_refptr<ShellLinkItem> > URLPair;