[TabMetrics] Add signals that mark the start and end of session restore.

chrome/browser/resource_coordinator/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_RESOURCE_COORDINATOR_TAB_MANAGER_H_
 #define CHROME_BROWSER_RESOURCE_COORDINATOR_TAB_MANAGER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 138 matching lines @@
   bool CanSuspendBackgroundedRenderer(int render_process_id) const;
 
   // Returns true if |first| is considered less desirable to be killed than
   // |second|.
   static bool CompareTabStats(const TabStats& first, const TabStats& second);
 
   // Returns a unique ID for a WebContents. Do not cast back to a pointer, as
   // the WebContents could be deleted if the user closed the tab.
   static int64_t IdFromWebContents(content::WebContents* web_contents);
 
+  void OnSessionRestoreStarted();
+  void OnSessionRestoreEnded();
+
+  bool IsInSessionRestore() const { return in_session_restore_; }
+
  private:
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, PurgeBackgroundRenderer);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ActivateTabResetPurgeState);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, ShouldPurgeAtDefaultTime);
   FRIEND_TEST_ALL_PREFIXES(TabManagerTest, DefaultTimeToPurgeInCorrectRange);
   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);
@@ skipping 207 matching lines @@
   // be crawled as the authoritative source of tabs, otherwise the BrowserList
   // and associated Browser objects are crawled. The list must be sorted in
   // z-order, from top to bottom.
   // TODO(chrisha): Factor out tab-strip model enumeration to a helper class,
   //     and make a delegate that centralizes all testing seams.
   std::vector<BrowserInfo> test_browser_info_list_;
 
   // List of observers that will receive notifications on state changes.
   base::ObserverList<TabManagerObserver> observers_;
 
+  bool in_session_restore_;
+
   // Weak pointer factory used for posting delayed tasks.
   base::WeakPtrFactory<TabManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TabManager);
 };
 
 }  // namespace resource_coordinator
 
 #endif  // CHROME_BROWSER_RESOURCE_COORDINATOR_TAB_MANAGER_H_