[Sync] Add tab sync latency UMA

chrome/browser/ui/webui/foreign_session_handler.cc

 // Copyright (c) 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/ui/webui/foreign_session_handler.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/i18n/time_formatting.h"
 #include "base/memory/scoped_vector.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
 #include "base/values.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sessions/session_restore.h"
 #include "chrome/browser/sync/profile_sync_service.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
 #include "chrome/browser/ui/host_desktop.h"
 #include "chrome/browser/ui/webui/ntp/new_tab_ui.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/url_constants.h"
@@ skipping 17 matching lines @@
 
 // Comparator function for use with std::sort that will sort sessions by
 // descending modified_time (i.e., most recent first).
 bool SortSessionsByRecency(const SyncedSession* s1, const SyncedSession* s2) {
   return s1->modified_time > s2->modified_time;
 }
 
 }  // namepace
 
 ForeignSessionHandler::ForeignSessionHandler() {
+  load_attempt_time_ = base::TimeTicks::Now();
 }
 
 // static
 void ForeignSessionHandler::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterDictionaryPref(prefs::kNtpCollapsedForeignSessions);
 }
 
 // static
 void ForeignSessionHandler::OpenForeignSessionTab(
@@ skipping 152 matching lines @@
       now < time ? base::TimeDelta() : now - time);
 }
 
 void ForeignSessionHandler::HandleGetForeignSessions(
     const base::ListValue* /*args*/) {
   OpenTabsUIDelegate* open_tabs = GetOpenTabsUIDelegate(web_ui());
   std::vector<const SyncedSession*> sessions;
 
   base::ListValue session_list;
   if (open_tabs && open_tabs->GetAllForeignSessions(&sessions)) {
+    if (!load_attempt_time_.is_null()) {
+      UMA_HISTOGRAM_TIMES("Sync.SessionsRefreshDelay",
+                          base::TimeTicks::Now() - load_attempt_time_);
+      load_attempt_time_ = base::TimeTicks();
+    }
+
     // Sort sessions from most recent to least recent.
     std::sort(sessions.begin(), sessions.end(), SortSessionsByRecency);
 
     // Use a pref to keep track of sessions that were collapsed by the user.
     // To prevent the pref from accumulating stale sessions, clear it each time
     // and only add back sessions that are still current.
     DictionaryPrefUpdate pref_update(Profile::FromWebUI(web_ui())->GetPrefs(),
                                      prefs::kNtpCollapsedForeignSessions);
     base::DictionaryValue* current_collapsed_sessions = pref_update.Get();
     scoped_ptr<base::DictionaryValue> collapsed_sessions(
@@ skipping 169 matching lines @@
       last_synced < base::TimeDelta::FromMinutes(1) ?
           l10n_util::GetStringUTF16(IDS_SYNC_TIME_JUST_NOW) :
           ui::TimeFormat::Simple(ui::TimeFormat::FORMAT_ELAPSED,
                                  ui::TimeFormat::LENGTH_SHORT, last_synced));
   dictionary->SetInteger("sessionId", window.window_id.id());
   dictionary->Set("tabs", tab_values.release());
   return true;
 }
 
 }  // namespace browser_sync