Refactor Extension initialization logic. Add tracing and additional histogram.

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 8d72dcc3fc945b9cf3776d81a91bc21080c577b5..d9b35d1388b3ed033189c1b1905342540e2845e9 100644
--- a/chrome/browser/extensions/installed_loader.cc
+++ b/chrome/browser/extensions/installed_loader.cc
@@ -229,9 +229,9 @@ void InstalledLoader::Load(const ExtensionInfo& info, bool write_to_prefs) {
 }
 
 void InstalledLoader::LoadAllExtensions() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

[Yoyo Zhou, 2015/02/25 19:34:29]

DCHECK_CURRENTLY_ON()

[rkaplow, 2015/02/25 19:59:50]

Done.

   TRACE_EVENT0("browser,startup", "InstalledLoader::LoadAllExtensions");
-  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
+  SCOPED_UMA_HISTOGRAM_TIMER("Extensions.LoadAllTime2");
   base::TimeTicks start_time = base::TimeTicks::Now();
 
   Profile* profile = extension_service_->profile();
@@ -307,6 +307,11 @@ void InstalledLoader::LoadAllExtensions() {
 
   UMA_HISTOGRAM_TIMES("Extensions.LoadAllTime",
                       base::TimeTicks::Now() - start_time);
+  RecordExtensionsMetrics();
+}
+
+void InstalledLoader::RecordExtensionsMetrics() {
+  Profile* profile = extension_service_->profile();
 
   int app_user_count = 0;
   int app_external_count = 0;