Make stack sampling profiler sample beyond startup.

chrome/browser/chrome_browser_main.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chrome_browser_main.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <set>
@@ skipping 612 matching lines @@
 
 // BrowserMainParts ------------------------------------------------------------
 
 ChromeBrowserMainParts::ChromeBrowserMainParts(
     const content::MainFunctionParams& parameters)
     : parameters_(parameters),
       parsed_command_line_(parameters.command_line),
       result_code_(content::RESULT_CODE_NORMAL_EXIT),
       startup_watcher_(new StartupTimeBomb()),
       shutdown_watcher_(new ShutdownWatcherHelper()),
+      sampling_profiler_params_(
+          metrics::CallStackProfileParams::BROWSER_PROCESS,
+          metrics::CallStackProfileParams::UI_THREAD,
+          metrics::CallStackProfileParams::PROCESS_STARTUP,
+          metrics::CallStackProfileParams::MAY_SHUFFLE),
       sampling_profiler_(
           base::PlatformThread::CurrentId(),
-          StackSamplingConfiguration::Get()->
-              GetSamplingParamsForCurrentProcess(),
+          StackSamplingConfiguration::Get()
+              ->GetSamplingParamsForCurrentProcess(),
           metrics::CallStackProfileMetricsProvider::GetProfilerCallback(
-              metrics::CallStackProfileParams(
-                  metrics::CallStackProfileParams::BROWSER_PROCESS,
-                  metrics::CallStackProfileParams::UI_THREAD,
-                  metrics::CallStackProfileParams::PROCESS_STARTUP,
-                  metrics::CallStackProfileParams::MAY_SHUFFLE))),
+              &sampling_profiler_params_)),

[sky, 2017/07/12 21:42:58]

It's rather error prone to have callers be responsible for keeping around
parameters used to create an object. Can't GetProfilerCallback copy (or move)
the params?

[Alexei Svitkine (slow), 2017/07/13 17:58:22]

Done.

       profile_(NULL),
       run_message_loop_(true),
       local_state_(NULL) {
   if (StackSamplingConfiguration::Get()->IsProfilerEnabledForCurrentProcess())
     sampling_profiler_.Start();
 
   // If we're running tests (ui_task is non-null).
   if (parameters.ui_task)
     browser_defaults::enable_help_app = false;
 
@@ skipping 1413 matching lines @@
   chromeos::CrosSettings::Shutdown();
 #endif  // defined(OS_CHROMEOS)
 #endif  // defined(OS_ANDROID)
 }
 
 // Public members:
 
 void ChromeBrowserMainParts::AddParts(ChromeBrowserMainExtraParts* parts) {
   chrome_extra_parts_.push_back(parts);
 }