Profiler-instrumentation of the startup time.

chrome/app/chrome_main_delegate.cc

Index: chrome/app/chrome_main_delegate.cc
diff --git a/chrome/app/chrome_main_delegate.cc b/chrome/app/chrome_main_delegate.cc
index e17bf8128a60481133fadce18f5e95458de29590..986185374a10f6941e21b562cfccf29dcc34b96b 100644
--- a/chrome/app/chrome_main_delegate.cc
+++ b/chrome/app/chrome_main_delegate.cc
@@ -15,6 +15,7 @@
 #include "base/path_service.h"
 #include "base/process/memory.h"
 #include "base/process/process_handle.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "chrome/browser/chrome_content_browser_client.h"
@@ -971,3 +972,18 @@ ChromeMainDelegate::CreateContentUtilityClient() {
   return g_chrome_content_utility_client.Pointer();
 #endif
 }
+
+bool ChromeMainDelegate::EnableProfilerRecording() {
+  switch (chrome::VersionInfo::GetChannel()) {
+    case chrome::VersionInfo::CHANNEL_UNKNOWN:
+    case chrome::VersionInfo::CHANNEL_CANARY:
+      tracked_objects::ScopedTracker::Enable();

[vadimt, 2015/03/12 18:23:03]

We don't need BOTH returning bool and enabling.

[yao, 2015/03/12 18:32:19]

I don't really have a strong opinion, but what's the benefit of enabling it from
the caller instead of here? 

[vadimt, 2015/03/12 18:37:26]

Hypothetically, another implementation may override this, and there will be
duplication of tracked_objects::ScopedTracker::Enable();

So, I have a slight preference for simply returning bool, but it's up to you.

[yao, 2015/03/13 15:24:49]

Changed as you suggested. 

+      return true;
+    case chrome::VersionInfo::CHANNEL_DEV:
+    case chrome::VersionInfo::CHANNEL_BETA:
+    case chrome::VersionInfo::CHANNEL_STABLE:
+    default:
+      // Don't enable instrumentation.
+      return false;
+  }
+}