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

chrome/browser/sessions/session_restore.cc

Index: chrome/browser/sessions/session_restore.cc
diff --git a/chrome/browser/sessions/session_restore.cc b/chrome/browser/sessions/session_restore.cc
index c6692162035c06fdb0cb02d7c1b7714f178e2d53..7fdc1d5daa227d95a8526aef61f10a5429a8f6d4 100644
--- a/chrome/browser/sessions/session_restore.cc
+++ b/chrome/browser/sessions/session_restore.cc
@@ -297,10 +297,28 @@ class SessionRestoreImpl : public content::NotificationObserver {
     }
 
     if (succeeded) {
-      // Start Loading tabs.
       if (SessionRestore::GetSmartRestoreMode() !=
-          SessionRestore::SMART_RESTORE_MODE_OFF)
+          SessionRestore::SMART_RESTORE_MODE_OFF) {
+        if (SessionRestore::GetSmartRestoreMode() ==
+            SessionRestore::SMART_RESTORE_MODE_MRU) {
+          // Sanitize the last active time by keeping the same time lapse
+          // between tabs. The latest tab will have its time set to Now() while
+          // the rest of the tabs will have theirs set earlier.
+          base::TimeTicks now = base::TimeTicks::Now();
+          base::TimeTicks highest_time = base::TimeTicks::UnixEpoch();
+          for (const auto& tab : *contents_created) {
+            if (tab.contents()->GetLastActiveTime() > highest_time)
+              highest_time = tab.contents()->GetLastActiveTime();
+          }
+          for (const auto& tab : *contents_created) {
+            base::TimeDelta delta =
+                highest_time - tab.contents()->GetLastActiveTime();
+            tab.contents()->SetLastActiveTime(now - delta);
+          }
+        }
         std::stable_sort(contents_created->begin(), contents_created->end());
+      }
+      // Start Loading tabs.
       SessionRestoreDelegate::RestoreTabs(*contents_created, restore_started_);
     }
 
@@ -591,6 +609,17 @@ class SessionRestoreImpl : public content::NotificationObserver {
     // focused tab will be loaded by Browser, and TabLoader will load the rest.
     DCHECK(web_contents->GetController().NeedsReload());
 
+    // Restore the saved last active time since by default, the last active time
+    // of a WebContent is initially set to the creation time of the tab, which
+    // is not necessarly the same as the loading time. This makes sure that the
+    // state is preserved between restores. Also, since TimeTicks only make
+    // sense in their current session, these values are sanitized later on
+    // (before we start loading background tabs).
+    if (SessionRestore::GetSmartRestoreMode() ==
+        SessionRestore::SMART_RESTORE_MODE_MRU) {
+      web_contents->SetLastActiveTime(tab.last_active_time);

[sky, 2015/05/22 03:00:19]

I don't like pushing potentially bogus times to the webcontents. I would rather
you do the sanitizing first.

[Georges Khalil, 2015/05/22 20:14:09]

That was done because otherwise, by the time we sanitized the values, the wrong
ones had already been saved.

I worked around this by sanitizing the values earlier.

+    }
+
     return web_contents;
   }