[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>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "base/timer/timer.h"
 #include "build/build_config.h"
 #include "chrome/browser/resource_coordinator/tab_manager_observer.h"
 #include "chrome/browser/resource_coordinator/tab_stats.h"
+#include "chrome/browser/sessions/session_restore_observer.h"
 #include "chrome/browser/ui/browser_tab_strip_tracker.h"
 #include "chrome/browser/ui/tabs/tab_strip_model_observer.h"
 #include "ui/gfx/geometry/rect.h"
 
 class BrowserList;
 class GURL;
 class TabStripModel;
 
 namespace base {
 class TickClock;
@@ skipping 112 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);
 
+  // Return whether tabs are being loaded during session restore.
+  bool IsSessionRestoreLoadingTabs() const {

[ducbui, 2017/06/27 00:12:49]

I changed this function name from "IsInSessionRestoreTabLoading()" to
"IsSessionRestoreLoadingTabs()" so that it become consistent with methods of
SessionRestoreObserver.

+    return is_in_session_restore_tab_loading_;
+  }
+
  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 145 matching lines @@
   // Otherwise returns the new web_contents of the discarded tab.
   content::WebContents* DiscardTabImpl();
 
   // Returns true if tabs can be discarded only once.
   bool CanOnlyDiscardOnce() const;
 
   // Returns a list of BrowserInfo sorted in z-order from top to bottom. The
   // list is constructed from either |test_browser_info_list_| or BrowserList.
   std::vector<BrowserInfo> GetBrowserInfoList() const;
 
+  void OnSessionRestoreStartedLoadingTabs();
+  void OnSessionRestoreFinishedLoadingTabs();
+
   // Timer to periodically update the stats of the renderers.
   base::RepeatingTimer update_timer_;
 
   // Timer to periodically report whether a tab has been discarded since the
   // last time the timer has fired.
   base::RepeatingTimer recent_tab_discard_timer_;
 
   // A listener to global memory pressure events.
   std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 
@@ skipping 42 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 is_in_session_restore_tab_loading_;
+
+  class TabManagerSessionRestoreObserver;
+  std::unique_ptr<TabManagerSessionRestoreObserver> session_restore_observer_;
+
   // 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_