Profiler-instrumentation of the startup time.

content/browser/browser_main_runner.cc

Index: content/browser/browser_main_runner.cc
diff --git a/content/browser/browser_main_runner.cc b/content/browser/browser_main_runner.cc
index b12ccd6da25c855ea0f831d2373e63d9ff04261f..3c106759d07083863e412a473fed4ecf0d7a2417 100644
--- a/content/browser/browser_main_runner.cc
+++ b/content/browser/browser_main_runner.cc
@@ -10,7 +10,9 @@
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/statistics_recorder.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/trace_event/trace_event.h"
+#include "base/tracked_objects.h"
 #include "content/browser/browser_main_loop.h"
 #include "content/browser/browser_shutdown_profile_dumper.h"
 #include "content/browser/notification_service_impl.h"
@@ -126,6 +128,13 @@ class BrowserMainRunnerImpl : public BrowserMainRunner {
   }
 
   int Initialize(const MainFunctionParams& parameters) override {
+    // TODO(vadimt): Remove all tracked_objects references below once
+    // crbug.com/453640 is fixed.
+    tracked_objects::ThreadData::InitializeThreadContext("CrBrowserMain");
+
+    tracked_objects::ScopedTracker tracking_profile(
+        FROM_HERE_WITH_EXPLICIT_FUNCTION("BrowserMainRunnerImpl::Initialize"));

[vadimt, 2015/03/12 17:54:56]

"453640 BrowserMainRunnerImpl::Initialize"
I know, this is how I originally wrote this, but this better highlights the
temporary nature of this instrumentation.

[yao, 2015/03/12 18:16:17]

Done.

+
     TRACE_EVENT0("startup", "BrowserMainRunnerImpl::Initialize");
     // On Android we normally initialize the browser in a series of UI thread
     // tasks. While this is happening a second request can come from the OS or