[Tab Metrics] Measure FP, FCP and FMP for Foreground Tab during Session Restore

chrome/browser/resource_coordinator/tab_manager.cc

Index: chrome/browser/resource_coordinator/tab_manager.cc
diff --git a/chrome/browser/resource_coordinator/tab_manager.cc b/chrome/browser/resource_coordinator/tab_manager.cc
index 296ab6d8b93deb027ed47e431bc1c978648cc32b..d183dc874598d66c67c826109d2ae519c7ead128 100644
--- a/chrome/browser/resource_coordinator/tab_manager.cc
+++ b/chrome/browser/resource_coordinator/tab_manager.cc
@@ -144,6 +144,7 @@ TabManager::TabManager()
       browser_tab_strip_tracker_(this, nullptr, this),
       test_tick_clock_(nullptr),
       is_session_restore_loading_tabs_(false),
+      initial_session_restore_foreground_tab_changed_(false),
       weak_ptr_factory_(this) {
 #if defined(OS_CHROMEOS)
   delegate_.reset(new TabManagerDelegate(weak_ptr_factory_.GetWeakPtr()));
@@ -482,8 +483,10 @@ int64_t TabManager::IdFromWebContents(WebContents* web_contents) {
 }
 
 void TabManager::OnSessionRestoreStartedLoadingTabs() {
-  DCHECK(!is_session_restore_loading_tabs_);
   is_session_restore_loading_tabs_ = true;
+
+  // Needs to reset this flag for each session restore.
+  initial_session_restore_foreground_tab_changed_ = false;
 }
 
 void TabManager::OnSessionRestoreFinishedLoadingTabs() {
@@ -826,6 +829,10 @@ void TabManager::ActiveTabChanged(content::WebContents* old_contents,
     ReloadWebContentsIfDiscarded(new_contents,
                                  GetWebContentsData(new_contents));
   }
+
+  if (old_contents && !initial_session_restore_foreground_tab_changed_) {
+    initial_session_restore_foreground_tab_changed_ = true;
+  }
 }
 
 void TabManager::TabInsertedAt(TabStripModel* tab_strip_model,