Add some tracing for Profiles and Extensions.

chrome/browser/extensions/installed_loader.cc

Index: chrome/browser/extensions/installed_loader.cc
diff --git a/chrome/browser/extensions/installed_loader.cc b/chrome/browser/extensions/installed_loader.cc
index 16273508b1db4a491f5ce9162dc0d29aee103671..8d72dcc3fc945b9cf3776d81a91bc21080c577b5 100644
--- a/chrome/browser/extensions/installed_loader.cc
+++ b/chrome/browser/extensions/installed_loader.cc
@@ -10,6 +10,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/extensions/extension_action_manager.h"
@@ -228,6 +229,7 @@ void InstalledLoader::Load(const ExtensionInfo& info, bool write_to_prefs) {
 }
 
 void InstalledLoader::LoadAllExtensions() {
+  TRACE_EVENT0("browser,startup", "InstalledLoader::LoadAllExtensions");
   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   base::TimeTicks start_time = base::TimeTicks::Now();