Fix the number of JumpList slots assigned to each JumpList category

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 <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 189 matching lines @@
 
   JumpListUpdater jumplist_updater(app_id);
   if (!jumplist_updater.BeginUpdate())
     return;
 
   // Stops jumplist update if JumpListUpdater's start times out, as it's very
   // likely the following update steps will also take a long time.
   if (begin_update_timer.Elapsed() >= kTimeOutForJumplistUpdate)
     return;
 
-  // We allocate 60% of the given JumpList slots to "most-visited" items
-  // and 40% to "recently-closed" items, respectively.
-  // Nevertheless, if there are not so many items in |recently_closed_pages|,
-  // we give the remaining slots to "most-visited" items.
   // The default maximum number of items to display in JumpList is 10.
-  // https://msdn.microsoft.com/en-us/library/windows/desktop/dd378398(v=vs.85).aspx
-  const int kMostVisited = 60;
-  const int kRecentlyClosed = 40;
+  // https://msdn.microsoft.com/library/windows/desktop/dd378398.aspx
+  // The "Most visited" category title always takes 1 of the JumpList slots if
+  // |most_visited_pages| isn't empty.
+  // The "Recently closed" category title will also take 1 if
+  // |recently_closed_pages| isn't empty.
+  // For the remaining slots, we allocate 5/8 (i.e., 5 slots if both categories
+  // present) to "most-visited" items and 3/8 (i.e., 3 slots if both categories
+  // present) to "recently-closed" items, respectively.
+
+  const int kMostVisited = 50;
+  const int kRecentlyClosed = 30;
   const int kTotal = kMostVisited + kRecentlyClosed;
+
+  // Adjust the available jumplist slots to account for the category titles.
+  size_t user_max_items_adjusted = jumplist_updater.user_max_items();
+  if (!most_visited_pages.empty())
+    --user_max_items_adjusted;
+  if (!recently_closed_pages.empty())
+    --user_max_items_adjusted;
+
   size_t most_visited_items =
-      MulDiv(jumplist_updater.user_max_items(), kMostVisited, kTotal);
-  size_t recently_closed_items =
-      jumplist_updater.user_max_items() - most_visited_items;
+      MulDiv(user_max_items_adjusted, kMostVisited, kTotal);
+  size_t recently_closed_items = user_max_items_adjusted - most_visited_items;
   if (recently_closed_pages.size() < recently_closed_items) {
     most_visited_items += recently_closed_items - recently_closed_pages.size();
     recently_closed_items = recently_closed_pages.size();
   }
 
   // Delete the content in JumpListIcons folder and log the results to UMA.
   DeleteDirectoryContentAndLogResults(icon_dir, kFileDeleteLimit);
 
   // If JumpListIcons directory doesn't exist (we have tried to create it
   // already) or is not empty, skip updating the jumplist icons. The jumplist
@@ skipping 201 matching lines @@
   // As noted above, we create a ShellLinkItem objects with the following
   // parameters.
   // * arguments
   //   The last URL of the tab object.
   // * title
   //   The title of the last URL.
   // * icon
   //   An empty string. This value is to be updated in OnFaviconDataAvailable().
   // This code is copied from
   // RecentlyClosedTabsHandler::TabRestoreServiceChanged() to emulate it.
-  const int kRecentlyClosedCount = 4;
+  const int kRecentlyClosedCount = 3;
   sessions::TabRestoreService* tab_restore_service =
       TabRestoreServiceFactory::GetForProfile(profile_);
   for (const auto& entry : tab_restore_service->entries()) {
     switch (entry->type) {
       case sessions::TabRestoreService::TAB:
         AddTab(static_cast<const sessions::TabRestoreService::Tab&>(*entry),
                &temp_list, kRecentlyClosedCount);
         break;
       case sessions::TabRestoreService::WINDOW:
         AddWindow(
@@ skipping 177 matching lines @@
 void JumpList::TopSitesLoaded(history::TopSites* top_sites) {
 }
 
 void JumpList::TopSitesChanged(history::TopSites* top_sites,
                                ChangeReason change_reason) {
   top_sites->GetMostVisitedURLs(
       base::Bind(&JumpList::OnMostVisitedURLsAvailable,
                  weak_ptr_factory_.GetWeakPtr()),
       false);
 }