Track thread activities in order to diagnose hangs.

chrome/browser/chrome_browser_field_trials_desktop.cc

Index: chrome/browser/chrome_browser_field_trials_desktop.cc
diff --git a/chrome/browser/chrome_browser_field_trials_desktop.cc b/chrome/browser/chrome_browser_field_trials_desktop.cc
index 3970bf2f0b90b873b2ea5497cef6a28e509ec351..12bf0e5abb94a63658a5d6a7c3c69d2758915846 100644
--- a/chrome/browser/chrome_browser_field_trials_desktop.cc
+++ b/chrome/browser/chrome_browser_field_trials_desktop.cc
@@ -7,8 +7,11 @@
 #include <string>
 
 #include "base/command_line.h"
+#include "base/debug/activity_tracker.h"
 #include "base/metrics/field_trial.h"
+#include "base/path_service.h"
 #include "chrome/browser/prerender/prerender_field_trial.h"
+#include "chrome/common/chrome_paths.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/variations/variations_util.h"
 #include "components/variations/variations_associated_data.h"
@@ -52,6 +55,11 @@ void SetupDesktopFieldTrials(const base::CommandLine& parsed_command_line) {
   prerender::ConfigurePrerender(parsed_command_line);
   SetupLightSpeedTrials();
   SetupStunProbeTrial();
+
+  base::FilePath activity_file;
+  if (base::PathService::Get(chrome::DIR_USER_DATA, &activity_file))
+    activity_file = activity_file.AppendASCII("ActivityTracker");
+  base::debug::SetupGlobalActivityTrackerFieldTrial(activity_file);

[manzagop (departed), 2016/06/01 21:59:40]

Should this be inside the if?
If so, should you add uma metric for failures?

[bcwhite, 2016/06/02 16:18:16]

Get() should always return the same value for a given key at a given place in
the code.  I'll just turn this into a DCHECK.

 }
 
 }  // namespace chrome