Enable startup profiling by Win x64 stack sampling profiler

chrome/browser/chrome_browser_main.cc

Index: chrome/browser/chrome_browser_main.cc
diff --git a/chrome/browser/chrome_browser_main.cc b/chrome/browser/chrome_browser_main.cc
index fb5034032e2085bdb551bd929c5420f4eb78b692..45d43ff09686daf433a9d3816d9c99bff7eb10ed 100644
--- a/chrome/browser/chrome_browser_main.cc
+++ b/chrome/browser/chrome_browser_main.cc
@@ -577,11 +577,14 @@ ChromeBrowserMainParts::ChromeBrowserMainParts(
       startup_watcher_(new StartupTimeBomb()),
       shutdown_watcher_(new ShutdownWatcherHelper()),
       browser_field_trials_(parameters.command_line),
+      sampling_profiler_(base::PlatformThread::CurrentId(),
+                         GetStartupSamplingParams()),
       profile_(NULL),
       run_message_loop_(true),
       notify_result_(ProcessSingleton::PROCESS_NONE),
       local_state_(NULL),
       restart_last_session_(false) {
+  sampling_profiler_.Start();
   // If we're running tests (ui_task is non-null).
   if (parameters.ui_task)
     browser_defaults::enable_help_app = false;
@@ -724,6 +727,19 @@ void ChromeBrowserMainParts::RecordBrowserStartupTime() {
   new LoadCompleteListener();
 }
 
+// static
+base::StackSamplingProfiler::SamplingParams

[cpu_(ooo_6.6-7.5), 2015/04/07 00:36:52]

this function does not need to be exposed to the interface (in the .h file) so
please put this function in as a freestanding function in this file, ideally in
the unnamed namespace.

+ChromeBrowserMainParts::GetStartupSamplingParams() {
+  // Sample at 10Hz for 30 seconds.
+  base::StackSamplingProfiler::SamplingParams params;
+  params.initial_delay = base::TimeDelta::FromMilliseconds(0);
+  params.bursts = 1;
+  params.samples_per_burst = 300;
+  params.sampling_interval = base::TimeDelta::FromMilliseconds(100);
+  params.preserve_sample_ordering = false;
+  return params;
+}
+
 // -----------------------------------------------------------------------------
 // TODO(viettrungluu): move more/rest of BrowserMain() into BrowserMainParts.