Discardable property support on TabManager

chrome/browser/memory/tab_manager_web_contents_data.h

Index: chrome/browser/memory/tab_manager_web_contents_data.h
diff --git a/chrome/browser/memory/tab_manager_web_contents_data.h b/chrome/browser/memory/tab_manager_web_contents_data.h
index 4830b773f7fdd896f0aac3f4b97ed167e3bee23c..c5e49b0aee6bb7c509994b2cd201b59f0d794021 100644
--- a/chrome/browser/memory/tab_manager_web_contents_data.h
+++ b/chrome/browser/memory/tab_manager_web_contents_data.h
@@ -72,6 +72,12 @@ class TabManager::WebContentsData
   // |test_tick_clock_| for more details.
   void set_test_tick_clock(base::TickClock* test_tick_clock);
 
+  // Sets/clears the discardable state of the tab.
+  void SetDiscardableState(bool state);
+
+  // Returns true if the tab is discardable by auto discarding feature.
+  bool IsDiscardable();
+
  private:
   // Needed to access tab_data_.
   FRIEND_TEST_ALL_PREFIXES(TabManagerWebContentsDataTest, CopyState);
@@ -99,6 +105,8 @@ class TabManager::WebContentsData
     base::TimeTicks last_inactive_time_;
     // Site Engagement score (set to -1 if not available).
     double engagement_score_;
+    // Is tab eligible for auto discarding by TabManager? Defaults to true.
+    bool is_discardable;
   };
 
   // Returns either the system's clock or the test clock. See |test_tick_clock_|