Log the ratio of the duration spent adding the two JumpList categories

chrome/browser/win/jumplist.cc

Index: chrome/browser/win/jumplist.cc
diff --git a/chrome/browser/win/jumplist.cc b/chrome/browser/win/jumplist.cc
index 7ebb5eab0553e7be09175a4f82c941bac03e2de6..9e641789593c95874358a947f85e66fdf8f47a44 100644
--- a/chrome/browser/win/jumplist.cc
+++ b/chrome/browser/win/jumplist.cc
@@ -753,6 +753,9 @@ void JumpList::CreateNewJumpListAndNotifyOS(
     return;
   }
 
+  base::TimeDelta most_visited_category_time =
+      add_custom_category_timer.Elapsed();
+
   // Update the "Recently Closed" category of the JumpList.
   if (!jumplist_updater.AddCustomCategory(
           l10n_util::GetStringUTF16(IDS_RECENTLY_CLOSED), recently_closed_pages,
@@ -760,9 +763,22 @@ void JumpList::CreateNewJumpListAndNotifyOS(
     return;
   }
 
+  base::TimeDelta add_category_total_time = add_custom_category_timer.Elapsed();
+
+  double most_visited_over_recently_closed =
+      most_visited_category_time.InMillisecondsF() /
+      (add_category_total_time - most_visited_category_time).InMillisecondsF();

[Ilya Sherman, 2017/07/04 03:41:19]

nit: Mebbe move this into the if-stmt?

[chengx, 2017/07/04 06:02:16]

Done.

+
+  if (recently_closed_pages.size() == kRecentlyClosedItems &&
+      most_visited_pages.size() == kMostVisitedItems) {
+    // TODO(chengx): Remove the UMA histogram after fixing crbug/736530.
+    UMA_HISTOGRAM_COUNTS_100("WinJumplist.AddCategoryTimeComparison",
+                             (int)(most_visited_over_recently_closed * 10));

[Ilya Sherman, 2017/07/04 03:41:19]

Why are you multiplying by 10?  It's not clear to me from this code, nor from
the histogram description.

[chengx, 2017/07/04 06:02:16]

The ration is typically between 1 and 10. I multiply it by 10 to retain some
precision as the UMA histogram casts the floating point to integer.  I've added
the comment.

+  }
+
   // If AddCustomCategory takes longer than the maximum allowed time, abort the
   // current update and skip the next |kUpdatesToSkipUnderHeavyLoad| updates.
-  if (add_custom_category_timer.Elapsed() >= kTimeOutForAddCustomCategory) {
+  if (add_category_total_time >= kTimeOutForAddCustomCategory) {
     update_transaction->update_timeout = true;
     return;
   }