This adds periodic OOM score adjustment, based on the last access time

chrome/browser/tab_contents/tab_contents.h

Index: chrome/browser/tab_contents/tab_contents.h
diff --git a/chrome/browser/tab_contents/tab_contents.h b/chrome/browser/tab_contents/tab_contents.h
index 113bc72cf4a1657d61f61f8f45a95f017250cf66..8fc184445a63107c263181e86637df01964d98ad 100644
--- a/chrome/browser/tab_contents/tab_contents.h
+++ b/chrome/browser/tab_contents/tab_contents.h
@@ -318,6 +318,9 @@ class TabContents : public PageNavigator,
   // Invoked when the tab contents becomes selected. If you override, be sure
   // and invoke super's implementation.
   virtual void DidBecomeSelected();
+  base::TimeTicks last_selected_time() const {
+    return last_selected_time_;
+  }
 
   // Invoked when the tab contents becomes hidden.
   // NOTE: If you override this, call the superclass version too!
@@ -1253,6 +1256,9 @@ class TabContents : public PageNavigator,
   // The time that we started to close the tab.
   base::TimeTicks tab_close_start_time_;
 
+  // The time that this tab was last selected.
+  base::TimeTicks last_selected_time_;
+
   // Information about the language the page is in and has been translated to.
   LanguageState language_state_;