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 24ac405c820d75e2c19b92784cc03fe21829bc8d..8e79909d34daad51f5bc05d60ceba9ab33b86d54 100644
--- a/chrome/browser/win/jumplist.cc
+++ b/chrome/browser/win/jumplist.cc
@@ -55,6 +55,10 @@ using JumpListData = JumpList::JumpListData;
 
 namespace {
 
+// JumpList "Most Visited" category is forced to sync with the TopSites service
+// only after this number of tabs are closed after Chrome launches.
+constexpr int kTabClosedCountToDelayTopSitesSync = 3;
+
 // The delay before updating the JumpList to prevent update storms.
 constexpr base::TimeDelta kDelayForJumplistUpdate =
     base::TimeDelta::FromMilliseconds(3500);
@@ -181,6 +185,8 @@ JumpList::JumpList(Profile* profile)
     : RefcountedKeyedService(content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::UI)),
       profile_(profile),
+      tab_closed_count_(0),
+      initial_most_visited_update_done_(false),
       jumplist_data_(new base::RefCountedData<JumpListData>),
       task_id_(base::CancelableTaskTracker::kBadTaskId),
       update_jumplist_task_runner_(base::CreateCOMSTATaskRunnerWithTraits(
@@ -208,12 +214,9 @@ 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);
@@ -270,9 +273,9 @@ 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_);
@@ -303,6 +306,8 @@ void JumpList::TabRestoreServiceChanged(sessions::TabRestoreService* service) {
   // if we have a pending favicon request, cancel it here (it is out of date).
   CancelPendingUpdate();
 
+  ++tab_closed_count_;
+
   // Initialize the one-shot timer to update the the "Recently Closed" category
   // in a while. If there is already a request queued then cancel it and post
   // the new request. This ensures that JumpList update of the "Recently Closed"
@@ -514,6 +519,9 @@ void JumpList::TopSitesChanged(history::TopSites* top_sites,
 }
 
 void JumpList::DeferredTopSitesChanged() {
+  if (tab_closed_count_ < kTabClosedCountToDelayTopSitesSync)
+    return;
+
   scoped_refptr<history::TopSites> top_sites =
       TopSitesFactory::GetForProfile(profile_);
   if (top_sites) {
@@ -525,6 +533,17 @@ void JumpList::DeferredTopSitesChanged() {
 }
 
 void JumpList::DeferredTabRestoreServiceChanged() {
+  if (tab_closed_count_ < kTabClosedCountToDelayTopSitesSync) {
+    return;
+  } else if (!initial_most_visited_update_done_) {
+    scoped_refptr<history::TopSites> top_sites =
+        TopSitesFactory::GetForProfile(profile_);
+    if (top_sites) {
+      top_sites->SyncWithHistory();
+    }
+    initial_most_visited_update_done_ = true;
+  }
+
   // Create a list of ShellLinkItems from the "Recently Closed" pages.
   // As noted above, we create a ShellLinkItem objects with the following
   // parameters.
@@ -630,20 +649,12 @@ bool JumpList::UpdateJumpList(
   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;
 
   size_t most_visited_items =
       MulDiv(user_max_items_adjusted, kMostVisited, kTotal);

[gab, 2017/05/12 18:13:35]

Can we just make this 5 and recently closed 3. i.e. stop trying to load-balance?

[chengx, 2017/05/18 00:51:00]

I stopped load-balancing, and limited these two categories to 5 items and 3
items. 

   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;