[Session restore] Add MRU logic to loading of background pages.

chrome/browser/sessions/session_service.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/sessions/session_service.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 469 matching lines @@
     const SessionID& window_id,
     const SessionID& tab_id,
     const std::string& extension_app_id) {
   if (!ShouldTrackChangesToWindow(window_id))
     return;
 
   ScheduleCommand(sessions::CreateSetTabExtensionAppIDCommand(
                       tab_id, extension_app_id).Pass());
 }
 
+void SessionService::SetActivationTime(const SessionID& window_id,
+                                       const SessionID& tab_id,
+                                       base::TimeTicks activation_time) {
+  if (!ShouldTrackChangesToWindow(window_id))
+    return;
+
+  ScheduleCommand(

[sky, 2015/05/12 21:25:30]

Don't you want to gate this by SessionRestore::GetSmartRestoreMode() ==
SessionRestore::SMART_RESTORE_MODE_MRU) ? Otherwise you can't really compare
metrics relating to file information.

[Georges Khalil, 2015/05/15 16:55:30]

Good idea. I'm actually going to gate the call to this function instead, to
avoid creating the ID (see your other comment in browser.cc).

+      sessions::CreateActivationTimeCommand(tab_id, activation_time).Pass());
+}
+
 base::CancelableTaskTracker::TaskId SessionService::GetLastSession(
     const SessionCallback& callback,
     base::CancelableTaskTracker* tracker) {
   // OnGotSessionCommands maps the SessionCommands to browser state, then run
   // the callback.
   return base_session_service_->ScheduleGetLastSessionCommands(
       base::Bind(&SessionService::OnGotSessionCommands,
                  weak_factory_.GetWeakPtr(),
                  callback),
       tracker);
@@ skipping 220 matching lines @@
   if (tab_to_available_range) {
     (*tab_to_available_range)[session_id.id()] =
         std::pair<int, int>(min_index, max_index);
   }
 
   if (is_pinned) {
     base_session_service_->AppendRebuildCommand(
         sessions::CreatePinnedStateCommand(session_id, true));
   }
 
+  // This works because we are persisting the last activation when restoring

[sky, 2015/05/12 21:25:30]

I don't understand this comment. It likely can be nuked.

[Georges Khalil, 2015/05/15 16:55:30]

Removed.

+  // tabs.
+  base_session_service_->AppendRebuildCommand(
+      sessions::CreateActivationTimeCommand(session_id,
+                                            tab->GetLastActiveTime()));
+
   extensions::TabHelper* extensions_tab_helper =
       extensions::TabHelper::FromWebContents(tab);
   if (extensions_tab_helper->extension_app()) {
     base_session_service_->AppendRebuildCommand(
         sessions::CreateSetTabExtensionAppIDCommand(
             session_id,
             extensions_tab_helper->extension_app()->id()));
   }
 
   const std::string& ua_override = tab->GetUserAgentOverride();
@@ skipping 353 matching lines @@
   for (chrome::BrowserIterator it; !it.done(); it.Next()) {
     if ((*it)->profile() == profile())
       return;
   }
   DeleteSessionOnlyData(profile());
 }
 
 sessions::BaseSessionService* SessionService::GetBaseSessionServiceForTest() {
   return base_session_service_.get();
 }