Made the NavigationTracingObserver always be active whenever background tracing is active

chrome/browser/tracing/navigation_tracing.cc

Index: chrome/browser/tracing/navigation_tracing.cc
diff --git a/chrome/browser/tracing/navigation_tracing.cc b/chrome/browser/tracing/navigation_tracing.cc
index db4c5a8a7cdbc977628a88cdf2cfceddc6177d4b..5655b05047bf0fd27d022b6d4ae583a74b2d42d8 100644
--- a/chrome/browser/tracing/navigation_tracing.cc
+++ b/chrome/browser/tracing/navigation_tracing.cc
@@ -78,6 +78,10 @@ void SetupNavigationTracing() {
       content::BackgroundTracingManager::NO_DATA_FILTERING);
 }
 
+bool NavigationTracingObserver::IsEnabled() {
+  return content::BackgroundTracingManager::GetInstance()->HasActiveScenario();
+}
+
 NavigationTracingObserver::NavigationTracingObserver(
     content::WebContents* web_contents)
     : content::WebContentsObserver(web_contents) {