Discardable property support on TabManager

chrome/browser/memory/tab_manager.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_MEMORY_TAB_MANAGER_H_
 #define CHROME_BROWSER_MEMORY_TAB_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 110 matching lines @@
   void set_test_tick_clock(base::TickClock* test_tick_clock);
 
   // Returns the list of the stats for all renderers. Must be called on the UI
   // thread.
   TabStatsList GetUnsortedTabStats();
 
   // Add/remove observers.
   void AddObserver(TabManagerObserver* observer);
   void RemoveObserver(TabManagerObserver* observer);
 
+  // Returns the auto-discardable state of the tab. When true, the tab is
+  // eligible to be automatically discarded when critical memory pressure hits,
+  // otherwise the tab is ignored and will never be automatically discarded.
+  // Note that this property doesn't block the discarding of the tab via other
+  // methods (about:discards for instance).
+  bool IsTabAutoDiscardable(content::WebContents* contents) const;
+
+  // Sets/clears the auto-discardable state of the tab.
+  void SetTabAutoDiscardableState(content::WebContents* contents, bool state);
+
  private:
+  FRIEND_TEST_ALL_PREFIXES(TabManagerTest, AutoDiscardable);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, CanOnlyDiscardOnce);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ChildProcessNotifications);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, Comparator);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DiscardedTabKeepsLastActiveTime);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DiscardWebContentsAt);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, InvalidOrEmptyURL);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, IsInternalPage);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, OomPressureListener);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectPDFPages);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectRecentlyUsedTabs);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ProtectVideoTabs);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ReloadDiscardedTabContextMenu);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, TabManagerBasics);
 
   // This is needed so WebContentsData can call OnDiscardedStateChange.
   friend class WebContensData;
 
   // Called by WebContentsData whenever the discard state of a WebContents
   // changes, so that observers can be informed.
   void OnDiscardedStateChange(content::WebContents* contents,
                               bool is_discarded);
 
+  // Called by WebContentsData whenever the auto-discardable state of a
+  // WebContents changes, so that observers can be informed.
+  void OnAutoDiscardableStateChange(content::WebContents* contents,
+                                    bool is_auto_discardable);
+
   // The time that a renderer is given to react to a memory pressure
   // notification before another renderer is also notified. This prevents all
   // renderers from receiving and acting upon notifications simultaneously,
   // which can quickly overload a system. Exposed for unittesting.
   // NOTE: This value needs to be big enough to allow a process to get over the
   // hump in responding to memory pressure, so there aren't multiple processes
   // fighting for CPU and worse, temporary memory, while trying to free things
   // up. Similarly, it shouldn't be too large otherwise it will take too long
   // for the entire system to respond. Ideally, there would be a callback from a
   // child process indicating that the message has been handled. In the meantime
@@ skipping 184 matching lines @@
 
   // Weak pointer factory used for posting delayed tasks to task_runner_.
   base::WeakPtrFactory<TabManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TabManager);
 };
 
 }  // namespace memory
 
 #endif  // CHROME_BROWSER_MEMORY_TAB_MANAGER_H_