Use layout test support flag to turn on single thread compositor proxy scheduler

content/shell/renderer/test_runner/web_test_proxy.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 "content/shell/renderer/test_runner/web_test_proxy.h"
 
 #include <cctype>
 
 #include "base/callback_helpers.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/trace_event/trace_event.h"
-#include "content/public/common/content_switches.h"
 #include "content/shell/renderer/test_runner/accessibility_controller.h"
 #include "content/shell/renderer/test_runner/event_sender.h"
 #include "content/shell/renderer/test_runner/mock_color_chooser.h"
 #include "content/shell/renderer/test_runner/mock_credential_manager_client.h"
 #include "content/shell/renderer/test_runner/mock_screen_orientation_client.h"
 #include "content/shell/renderer/test_runner/mock_web_speech_recognizer.h"
 #include "content/shell/renderer/test_runner/mock_web_user_media_client.h"
 #include "content/shell/renderer/test_runner/spell_check_client.h"
 #include "content/shell/renderer/test_runner/test_interfaces.h"
 #include "content/shell/renderer/test_runner/test_plugin.h"
@@ skipping 356 matching lines @@
   return result;
 }
 }
 
 WebTestProxyBase::WebTestProxyBase()
     : test_interfaces_(NULL),
       delegate_(NULL),
       web_widget_(NULL),
       spellcheck_(new SpellCheckClient(this)),
       chooser_count_(0) {
-  // TODO(enne): using the scheduler introduces additional composite steps
-  // that create flakiness.  This should go away eventually.
-  base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kDisableSingleThreadProxyScheduler);
   Reset();
 }
 
 WebTestProxyBase::~WebTestProxyBase() {
   test_interfaces_->WindowClosed(this);
 }
 
 void WebTestProxyBase::SetInterfaces(WebTestInterfaces* interfaces) {
   test_interfaces_ = interfaces->GetTestInterfaces();
   test_interfaces_->WindowOpened(this);
@@ skipping 987 matching lines @@
   // to cancel the input method's ongoing composition session.
   if (web_widget_)
     web_widget_->confirmComposition();
 }
 
 blink::WebString WebTestProxyBase::acceptLanguages() {
   return blink::WebString::fromUTF8(accept_languages_);
 }
 
 }  // namespace content