Register a default instance of FeatureList for content browser.

content/browser/browser_main_loop.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 "content/browser/browser_main_loop.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/feature_list.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/memory_pressure_monitor.h"
 #include "base/metrics/field_trial.h"
 #include "base/metrics/histogram.h"
 #include "base/pending_task.h"
 #include "base/power_monitor/power_monitor.h"
 #include "base/power_monitor/power_monitor_device_source.h"
 #include "base/process/process_metrics.h"
 #include "base/profiler/scoped_profile.h"
@@ skipping 664 matching lines @@
 
 int BrowserMainLoop::PreCreateThreads() {
   if (parts_) {
     TRACE_EVENT0("startup",
         "BrowserMainLoop::CreateThreads:PreCreateThreads");
     TRACK_SCOPED_REGION("Startup", "BrowserMainLoop::PreCreateThreads");
 
     result_code_ = parts_->PreCreateThreads();
   }
 
+  // Initialize an instance of FeatureList. This will be a no-op if an instance
+  // was already set up by the embedder.
+  base::FeatureList::InitializeInstance();
+
   // TODO(chrisha): Abstract away this construction mess to a helper function,
   // once MemoryPressureMonitor is made a concrete class.
 #if defined(OS_CHROMEOS)
   if (chromeos::switches::MemoryPressureHandlingEnabled()) {
     memory_pressure_monitor_.reset(new base::chromeos::MemoryPressureMonitor(
         chromeos::switches::GetMemoryPressureThresholds()));
   }
 #elif defined(OS_MACOSX) && !defined(OS_IOS)
   memory_pressure_monitor_.reset(new base::mac::MemoryPressureMonitor());
 #elif defined(OS_WIN)
@@ skipping 719 matching lines @@
   DCHECK(is_tracing_startup_for_duration_);
 
   is_tracing_startup_for_duration_ = false;
   TracingController::GetInstance()->DisableRecording(
       TracingController::CreateFileSink(
           startup_trace_file_,
           base::Bind(OnStoppedStartupTracing, startup_trace_file_)));
 }
 
 }  // namespace content