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

chrome/browser/sessions/session_restore_delegate.cc

Index: chrome/browser/sessions/session_restore_delegate.cc
diff --git a/chrome/browser/sessions/session_restore_delegate.cc b/chrome/browser/sessions/session_restore_delegate.cc
index 28b2966f818c6a42ba26c4b1c9d1017cd44b0ec6..42f97e099456cf0e0ab0e63a04388e4e886805d8 100644
--- a/chrome/browser/sessions/session_restore_delegate.cc
+++ b/chrome/browser/sessions/session_restore_delegate.cc
@@ -33,15 +33,18 @@ bool IsInternalPage(const GURL& url) {
 
 }  // namespace
 
-SessionRestoreDelegate::RestoredTab::RestoredTab(content::WebContents* contents,
-                                                 bool is_active,
-                                                 bool is_app,
-                                                 bool is_pinned)
+SessionRestoreDelegate::RestoredTab::RestoredTab(
+    content::WebContents* contents,
+    bool is_active,
+    bool is_app,
+    bool is_pinned,
+    base::TimeTicks last_activation_time)
     : contents_(contents),
       is_active_(is_active),
       is_app_(is_app),
       is_internal_page_(IsInternalPage(contents->GetLastCommittedURL())),
-      is_pinned_(is_pinned) {
+      is_pinned_(is_pinned),
+      last_activation_time_(last_activation_time) {
 }
 
 bool SessionRestoreDelegate::RestoredTab::operator<(
@@ -56,7 +59,10 @@ bool SessionRestoreDelegate::RestoredTab::operator<(
   // Apps should be loaded before normal tabs.
   if (is_app_ != right.is_app_)
     return is_app_;
-  // TODO(georgesak): Add criterion based on recency.
+  // Restore using MRU. Behind an experiment for now.
+  if (SessionRestore::GetSmartRestoreMode() ==
+      SessionRestore::SMART_RESTORE_MODE_MRU)
+    return last_activation_time_ > right.last_activation_time_;
   return false;
 }