Enable Initialization of the Task Scheduler by Default in the Browser Process

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 <map>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/debug/debugger.h"
 #include "base/feature_list.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/path_service.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/run_loop.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/sys_info.h"
-#include "base/task_scheduler/switches.h"
 #include "base/task_scheduler/task_scheduler.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/sequenced_worker_pool.h"

[fdoray, 2016/11/16 19:23:59]

Remove  #include "base/threading/sequenced_worker_pool.h"

[robliao, 2016/11/16 19:42:55]

Done.

 #include "base/time/default_tick_clock.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
 #include "chrome/browser/about_flags.h"
 #include "chrome/browser/after_startup_task_utils.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_process_impl.h"
@@ skipping 257 matching lines @@
 void AddFirstRunNewTabs(StartupBrowserCreator* browser_creator,
                         const std::vector<GURL>& new_tabs) {
   for (std::vector<GURL>::const_iterator it = new_tabs.begin();
        it != new_tabs.end(); ++it) {
     if (it->is_valid())
       browser_creator->AddFirstRunTab(*it);
   }
 }
 #endif  // !defined(OS_ANDROID) && !defined(OS_CHROMEOS)
 
-void MaybeInitializeTaskScheduler() {
-  static constexpr char kFieldTrialName[] = "BrowserScheduler";
-  std::map<std::string, std::string> variation_params;
-  if (!variations::GetVariationParams(kFieldTrialName, &variation_params)) {
-    DCHECK(!base::CommandLine::ForCurrentProcess()->HasSwitch(
-        switches::kEnableBrowserTaskScheduler))
-        << "The Browser Task Scheduler remains disabled with "
-        << switches::kEnableBrowserTaskScheduler
-        << " because there is no available variation param for this build or "
-           " the task scheduler is disabled in chrome://flags.";
-    return;
-  }
-
-  if (!task_scheduler_util::InitializeDefaultTaskScheduler(variation_params))
-    return;
-
-  // TODO(gab): Remove this when http://crbug.com/622400 concludes.
-  const auto sequenced_worker_pool_param =
-      variation_params.find("RedirectSequencedWorkerPools");
-  if (sequenced_worker_pool_param != variation_params.end() &&
-      sequenced_worker_pool_param->second == "true") {
-    base::SequencedWorkerPool::RedirectToTaskSchedulerForProcess();
-  }
-}
-
 // Returns the new local state object, guaranteed non-NULL.
 // |local_state_task_runner| must be a shutdown-blocking task runner.
 PrefService* InitializeLocalState(
     base::SequencedTaskRunner* local_state_task_runner,
     const base::CommandLine& parsed_command_line) {
   TRACE_EVENT0("startup", "ChromeBrowserMainParts::InitializeLocalState")
 
   // Load local state.  This includes the application locale so we know which
   // locale dll to load.  This also causes local state prefs to be registered.
   PrefService* local_state = g_browser_process->local_state();
@@ skipping 886 matching lines @@
 
   // Task Scheduler initialization needs to be here for the following reasons:
   //   * After |SetupFieldTrials()|: Initialization uses variations.
   //   * Before |SetupMetrics()|: |SetupMetrics()| uses the blocking pool. The
   //         Task Scheduler must do any necessary redirection before then.
   //   * Near the end of |PreCreateThreads()|: The TaskScheduler needs to be
   //         created before any other threads are (by contract) but it creates
   //         threads itself so instantiating it earlier is also incorrect.
   // To maintain scoping symmetry, if this line is moved, the corresponding
   // shutdown call may also need to be moved.
-  MaybeInitializeTaskScheduler();
+  task_scheduler_util::InitializeDefaultBrowserTaskScheduler();

[fdoray, 2016/11/16 19:23:59]

Remove "Default"?

[robliao, 2016/11/16 19:42:55]

Technically it is the default one (we provide it), so I'd rather leave it here.

 
   SetupMetrics();
 
   // ChromeOS needs ResourceBundle::InitSharedInstance to be called before this.
   // This also instantiates the IOThread which requests the metrics service and
   // must be after |SetupMetrics()|.
   browser_process_->PreCreateThreads();
 
   return content::RESULT_CODE_NORMAL_EXIT;
 }
@@ skipping 860 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);
 }