[Extensions][TaskScheduler] Update ActivityLog for scheduling migration

chrome/browser/extensions/activity_log/activity_log.cc

Index: chrome/browser/extensions/activity_log/activity_log.cc
diff --git a/chrome/browser/extensions/activity_log/activity_log.cc b/chrome/browser/extensions/activity_log/activity_log.cc
index e1fa65b92d5586db185b3784e18d5799d5cacc74..4775bccbf090837b29798b65e45d0c0caf8d247a 100644
--- a/chrome/browser/extensions/activity_log/activity_log.cc
+++ b/chrome/browser/extensions/activity_log/activity_log.cc
@@ -580,6 +580,7 @@ ActivityLog::ActivityLog(content::BrowserContext* context)
 
   // Check that the right threads exist for logging to the database.
   // If not, we shouldn't try to do things that require them.
+  // TODO(devlin): We can clean this up now that we use sequenced task runners.
   if (!BrowserThread::IsMessageLoopValid(BrowserThread::DB) ||
       !BrowserThread::IsMessageLoopValid(BrowserThread::FILE) ||
       !BrowserThread::IsMessageLoopValid(BrowserThread::IO)) {