[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 122f6bd73eb70bc170bab67c512cbc4fa47f4678..c3f3e401874e16a89bd840d1f292f607201dc125 100644
--- a/chrome/browser/resource_coordinator/tab_manager.cc
+++ b/chrome/browser/resource_coordinator/tab_manager.cc
@@ -162,6 +162,7 @@ TabManager::TabManager()
       browser_tab_strip_tracker_(this, nullptr, nullptr),
       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()));
@@ -507,6 +508,9 @@ 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() {
@@ -830,6 +834,10 @@ void TabManager::ActiveTabChanged(content::WebContents* old_contents,
     GetWebContentsData(old_contents)
         ->set_time_to_purge(GetTimeToPurge(min_time_to_purge_));
   }
+
+  if (old_contents && !initial_session_restore_foreground_tab_changed_) {
+    initial_session_restore_foreground_tab_changed_ = true;
+  }
 }
 
 void TabManager::TabInsertedAt(TabStripModel* tab_strip_model,