Add IsRestoringSession method to sessionRestorationBrowserAgent

This addition makes sure that calling the restoreSession method from
the agent has the same effect as calling it from the TabModel.
Also forward the call from TabModel to call IsRestoringSession of
SessionRestorationAgent.

Bug: 1010164, 783777
Change-Id: Ib4fdfb1c1fe4fc04515b8e4462f3f68df0c9453f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003911
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732967}

ios/chrome/browser/sessions/session_restoration_browser_agent.h

@@ -49,6 +49,11 @@ class SessionRestorationBrowserAgent
   // based on the value of |immediately|.
   void SaveSession(const bool immediately);
 
+  // Returns true if there is a session restoration in progress, otherwise it
+  // returns false. Note that this method can be called from the UI Thread.
+  // This method exists as a work around for crbug.com/763964.
+  bool IsRestoringSession();
+
  private:
   SessionRestorationBrowserAgent(Browser* browser,
                                  SessionServiceIOS* session_service);
@@ -71,6 +76,9 @@ class SessionRestorationBrowserAgent
 
   // Session Factory used to create session data for saving.
   SessionIOSFactory* session_ios_factory_;
+
+  // true when session restoration is in progress.
+  bool restoring_session_ = false;
 };
 
 #endif  // IOS_CHROME_BROWSER_SESSIONS_SESSION_RESTORATION_BROWSER_AGENT_H_

ios/chrome/browser/sessions/session_restoration_browser_agent.mm

@@ -72,6 +72,7 @@ bool SessionRestorationBrowserAgent::RestoreSessionWindow(
     SessionWindowIOS* window) {
   if (!window.sessions.count)
     return NO;
+  restoring_session_ = true;
 
   for (auto& observer : observers_) {
     observer.WillStartSessionRestoration();
@@ -149,9 +150,14 @@ bool SessionRestorationBrowserAgent::RestoreSessionWindow(
   for (auto& observer : observers_) {
     observer.SessionRestorationFinished(restored_web_states);
   }
+  restoring_session_ = false;
   return closed_ntp_tab;
 }
 
+bool SessionRestorationBrowserAgent::IsRestoringSession() {
+  return restoring_session_;
+}
+
 void SessionRestorationBrowserAgent::SaveSession(bool immediately) {
   if (!CanSaveSession())
     return;

ios/chrome/browser/tabs/tab_model.mm

@@ -440,20 +440,16 @@ void RecordMainFrameNavigationMetric(web::WebState* web_state) {
       ->IsWebUsageEnabled();
 }
 
+- (BOOL)isRestoringSession {
+  return _sessionRestorationBrowserAgent->IsRestoringSession();
+}
+
 - (BOOL)restoreSessionWindow:(SessionWindowIOS*)window
            forInitialRestore:(BOOL)initialRestore {
   DCHECK(_browserState);
 
   // It is only ok to pass a nil |window| during the initial restore.
   DCHECK(window || initialRestore);
-
-  // Setting the sesion progress to |YES|, so BVC can check it to work around
-  // crbug.com/763964.
-  _restoringSession = YES;
-  base::ScopedClosureRunner updateSessionRestorationProgress(base::BindOnce(^{
-    _restoringSession = NO;
-  }));
-
   return _sessionRestorationBrowserAgent->RestoreSessionWindow(window);
 }