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

chrome/browser/win/jumplist.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/win/jumplist.h"
 
 #include "base/base_paths.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ skipping 735 matching lines @@
 
   // Update the "Most Visited" category of the JumpList if it exists.
   // This update request is applied into the JumpList when we commit this
   // transaction.
   if (!jumplist_updater.AddCustomCategory(
           l10n_util::GetStringUTF16(IDS_NEW_TAB_MOST_VISITED),
           most_visited_pages, kMostVisitedItems)) {
     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,
           kRecentlyClosedItems)) {
     return;
   }
 
+  base::TimeDelta add_category_total_time = add_custom_category_timer.Elapsed();
+
+  if (recently_closed_pages.size() == kRecentlyClosedItems &&
+      most_visited_pages.size() == kMostVisitedItems) {
+    // TODO(chengx): Remove the UMA histogram after fixing crbug/736530.
+    double most_visited_over_recently_closed =
+        most_visited_category_time.InMillisecondsF() /
+        (add_category_total_time - most_visited_category_time)
+            .InMillisecondsF();
+
+    // The ratio above is typically between 1 and 10. Multiply it by 10 to
+    // retain decimal precision.
+    UMA_HISTOGRAM_COUNTS_100("WinJumplist.RatioAddCategoryTime",
+                             most_visited_over_recently_closed * 10);
+  }
+
   // 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;
   }
 
   // Update the "Tasks" category of the JumpList.
   if (!UpdateTaskCategory(&jumplist_updater, incognito_availability))
     return;
 
   base::ElapsedTimer commit_update_timer;
 
@@ skipping 87 matching lines @@
                                const URLIconCache& icons_cache) {
   // Put all cached icon file paths into a set.
   base::flat_set<base::FilePath> cached_files;
   cached_files.reserve(icons_cache.size());
 
   for (const auto& url_path_pair : icons_cache)
     cached_files.insert(url_path_pair.second);
 
   DeleteNonCachedFiles(icon_dir, cached_files);
 }