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

chrome/browser/sessions/session_service.cc

Index: chrome/browser/sessions/session_service.cc
diff --git a/chrome/browser/sessions/session_service.cc b/chrome/browser/sessions/session_service.cc
index 99de7204e61bdf7d52e078b0e979d175b29f58eb..596c493dda5f53fe76d0767c91f9545371f56155 100644
--- a/chrome/browser/sessions/session_service.cc
+++ b/chrome/browser/sessions/session_service.cc
@@ -487,6 +487,16 @@ void SessionService::SetTabExtensionAppID(
                       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) {
@@ -727,6 +737,12 @@ void SessionService::BuildCommandsForTab(const SessionID& window_id,
         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()) {