Defer syncing TopSites with history until the first tab closure

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 9054e20864d8e2a1c324c721d904440b9fabaf9f..d08ddb2ef38c6152daba414cd5d88f941000d1a7 100644
--- a/chrome/browser/win/jumplist.cc
+++ b/chrome/browser/win/jumplist.cc
@@ -221,12 +221,9 @@ JumpList::JumpList(Profile* profile)
   scoped_refptr<history::TopSites> top_sites =
       TopSitesFactory::GetForProfile(profile_);
   if (top_sites) {
-    // TopSites updates itself after a delay. This is especially noticable when
-    // your profile is empty. Ask TopSites to update itself when jumplist is
-    // initialized.
-    top_sites->SyncWithHistory();
     // Register as TopSitesObserver so that we can update ourselves when the
-    // TopSites changes.
+    // TopSites changes. TopSites updates itself after a delay. This is
+    // especially noticable when your profile is empty.
     top_sites->AddObserver(this);
   }
   tab_restore_service->AddObserver(this);
@@ -283,9 +280,9 @@ void JumpList::OnMostVisitedURLsAvailable(
     const history::MostVisitedURLList& urls) {
   DCHECK(CalledOnValidThread());
 
-  // At most 9 JumpList items can be displayed for the "Most Visited"
+  // At most 5 JumpList items can be displayed for the "Most Visited"
   // category.
-  const int kMostVistedCount = 9;
+  const int kMostVistedCount = 5;
   {
     JumpListData* data = &jumplist_data_->data;
     base::AutoLock auto_lock(data->list_lock_);
@@ -532,6 +529,12 @@ void JumpList::DeferredTopSitesChanged() {
     return;
   }
 
+  // Opening the first tab in one session triggers a TopSite history sync.
+  // Delay this sync till the first tab is closed to allow the "recently closed"
+  // category from last session stay longer.
+  if (!has_tab_closed_)
+    return;
+
   scoped_refptr<history::TopSites> top_sites =
       TopSitesFactory::GetForProfile(profile_);
   if (top_sites) {
@@ -548,6 +551,15 @@ void JumpList::DeferredTabRestoreServiceChanged() {
     return;
   }
 
+  // Force to do a TopSite history sync when closing a first tab in one session.

[grt (UTC plus 2), 2017/05/18 09:35:14]

nit: "Force a TopSite..."

[chengx, 2017/05/19 02:11:58]

Done.

+  if (!has_tab_closed_) {
+    has_tab_closed_ = true;
+    scoped_refptr<history::TopSites> top_sites =
+        TopSitesFactory::GetForProfile(profile_);
+    if (top_sites)
+      top_sites->SyncWithHistory();
+  }
+
   // Create a list of ShellLinkItems from the "Recently Closed" pages.
   // As noted above, we create a ShellLinkItem objects with the following
   // parameters.
@@ -642,34 +654,24 @@ bool JumpList::UpdateJumpList(
 
   // The default maximum number of items to display in JumpList is 10.
   // 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.
-  // Nevertheless, if there are not so many items in |recently_closed_pages|,
-  // we give the remaining slots to "most-visited" items.
+  // The "Most visited" and "Recently closed" category titles always takes 2 of
+  // the JumpList slots. For the remaining slots, we allocate 5/8 (i.e., 5 slots
+  // by default) to "most-visited" items and 3/8 (i.e., 3 slots by default) 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;
+  // Adjust the available jumplist slots to account for the two category titles.
+  size_t user_max_items_adjusted = jumplist_updater.user_max_items() - 2;
 
+  // Cap 5 items for "Most visited" category, and 3 items for "Recently closed"
+  // category.
+  user_max_items_adjusted = std::min((int)jumplist_updater.user_max_items(), 8);
   size_t 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();
-  }
 
   // Record the desired number of icons to create in this JumpList update.
   int icons_to_create = 0;