Reland "[Chromecast] Use base::FeatureList to control features."

chromecast/browser/cast_browser_main_parts.cc

 // Copyright 2014 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 "chromecast/browser/cast_browser_main_parts.h"
 
 #include <stddef.h>
 #include <string.h>
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/path_service.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "cc/base/switches.h"
 #include "chromecast/base/cast_constants.h"
+#include "chromecast/base/cast_features.h"
 #include "chromecast/base/cast_paths.h"
 #include "chromecast/base/cast_sys_info_util.h"
 #include "chromecast/base/chromecast_switches.h"
 #include "chromecast/base/metrics/cast_metrics_helper.h"
 #include "chromecast/base/metrics/grouped_histogram.h"
+#include "chromecast/base/pref_names.h"
 #include "chromecast/base/version.h"
 #include "chromecast/browser/cast_browser_context.h"
 #include "chromecast/browser/cast_browser_process.h"
 #include "chromecast/browser/cast_content_browser_client.h"
 #include "chromecast/browser/cast_memory_pressure_monitor.h"
 #include "chromecast/browser/cast_net_log.h"
 #include "chromecast/browser/devtools/remote_debugging_server.h"
 #include "chromecast/browser/geolocation/cast_access_token_store.h"
 #include "chromecast/browser/media/media_caps_impl.h"
 #include "chromecast/browser/metrics/cast_metrics_prefs.h"
@@ skipping 230 matching lines @@
   }
 }
 
 }  // namespace
 
 CastBrowserMainParts::CastBrowserMainParts(
     const content::MainFunctionParams& parameters,
     URLRequestContextFactory* url_request_context_factory)
     : BrowserMainParts(),
       cast_browser_process_(new CastBrowserProcess()),
+      field_trial_list_(nullptr),
       parameters_(parameters),
       url_request_context_factory_(url_request_context_factory),
       net_log_(new CastNetLog()),
       media_caps_(new media::MediaCapsImpl()) {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
   AddDefaultCommandLineSwitches(command_line);
 
 #if BUILDFLAG(IS_CAST_USING_CMA_BACKEND)
   media_resource_tracker_ = nullptr;
 #endif  // BUILDFLAG(IS_CAST_USING_CMA_BACKEND)
@@ skipping 115 matching lines @@
   breakpad::CrashDumpObserver::Create();
   breakpad::CrashDumpObserver::GetInstance()->RegisterClient(
       base::MakeUnique<breakpad::CrashDumpManager>(crash_dumps_dir,
                                                    kAndroidMinidumpDescriptor));
 #else
   base::FilePath home_dir;
   CHECK(PathService::Get(DIR_CAST_HOME, &home_dir));
   if (!base::CreateDirectory(home_dir))
     return 1;
 
+  scoped_refptr<PrefRegistrySimple> pref_registry(new PrefRegistrySimple());
+  metrics::RegisterPrefs(pref_registry.get());
+  PrefProxyConfigTrackerImpl::RegisterPrefs(pref_registry.get());
+  cast_browser_process_->SetPrefService(
+      PrefServiceHelper::CreatePrefService(pref_registry.get()));
+
+  // As soon as the PrefService is set, initialize the base::FeatureList, so
+  // objects initialized after this point can use features from
+  // base::FeatureList.
+  const auto* features_dict =
+      cast_browser_process_->pref_service()->GetDictionary(
+          prefs::kLatestDCSFeatures);
+  const auto* experiment_ids = cast_browser_process_->pref_service()->GetList(
+      prefs::kActiveDCSExperiments);
+  auto* command_line = base::CommandLine::ForCurrentProcess();
+  InitializeFeatureList(
+      *features_dict, *experiment_ids,
+      command_line->GetSwitchValueASCII(switches::kEnableFeatures),
+      command_line->GetSwitchValueASCII(switches::kDisableFeatures));
+
   // Hook for internal code
   cast_browser_process_->browser_client()->PreCreateThreads();
 
   // Set GL strings so GPU config code can make correct feature blacklisting/
   // whitelisting decisions.
   // Note: SetGLStrings can be called before GpuDataManager::Initialize.
   std::unique_ptr<CastSysInfo> sys_info = CreateSysInfo();
   content::GpuDataManager::GetInstance()->SetGLStrings(
       sys_info->GetGlVendor(), sys_info->GetGlRenderer(),
       sys_info->GetGlVersion());
 #endif
 
 #if defined(USE_AURA)
   cast_browser_process_->SetCastScreen(base::WrapUnique(new CastScreen()));
   DCHECK(!display::Screen::GetScreen());
   display::Screen::SetScreenInstance(cast_browser_process_->cast_screen());
 #endif
 
   content::ChildProcessSecurityPolicy::GetInstance()->RegisterWebSafeScheme(
       kChromeResourceScheme);
   return 0;
 }
 
 void CastBrowserMainParts::PreMainMessageLoopRun() {
-  scoped_refptr<PrefRegistrySimple> pref_registry(new PrefRegistrySimple());
-  metrics::RegisterPrefs(pref_registry.get());
-  PrefProxyConfigTrackerImpl::RegisterPrefs(pref_registry.get());
-  cast_browser_process_->SetPrefService(
-      PrefServiceHelper::CreatePrefService(pref_registry.get()));
 
 #if !defined(OS_ANDROID)
   memory_pressure_monitor_.reset(new CastMemoryPressureMonitor());
 #endif  // defined(OS_ANDROID)
 
   cast_browser_process_->SetNetLog(net_log_.get());
   url_request_context_factory_->InitializeOnUIThread(net_log_.get());
 
   cast_browser_process_->SetConnectivityChecker(ConnectivityChecker::Create(
       content::BrowserThread::GetTaskRunnerForThread(
@@ skipping 110 matching lines @@
 
 void CastBrowserMainParts::PostDestroyThreads() {
 #if !defined(OS_ANDROID)
   media_resource_tracker_->FinalizeAndDestroy();
   media_resource_tracker_ = nullptr;
 #endif
 }
 
 }  // namespace shell
 }  // namespace chromecast