Revert of [Temporary On Will revert on Fri] UI impl side painting default on

chrome/browser/chromeos/login/screenshot_testing/screenshot_testing_mixin.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 "chrome/browser/chromeos/login/screenshot_testing/screenshot_testing_mixin.h"
 
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 #include "ui/compositor/compositor_switches.h"
 
 namespace chromeos {
 
 ScreenshotTestingMixin::ScreenshotTestingMixin()
     : enable_test_screenshots_(false) {
 }
 
 ScreenshotTestingMixin::~ScreenshotTestingMixin() {
 }
 
 void ScreenshotTestingMixin::SetUpInProcessBrowserTestFixture() {
   enable_test_screenshots_ = screenshot_tester_.TryInitialize();
 }
 
 void ScreenshotTestingMixin::SetUpCommandLine(base::CommandLine* command_line) {
   if (enable_test_screenshots_) {
     command_line->AppendSwitch(switches::kEnablePixelOutputInTests);
-  } else {
-    command_line->AppendSwitch(switches::kUIDisableImplSidePainting);
+    command_line->AppendSwitch(switches::kUIEnableImplSidePainting);
   }
 }
 
 void ScreenshotTestingMixin::RunScreenshotTesting(
     const std::string& test_name) {
   if (enable_test_screenshots_) {
     SynchronizeAnimationLoadWithCompositor();
     screenshot_tester_.Run(test_name);
   }
 }
@@ skipping 17 matching lines @@
   waiter.Run();
 }
 
 void ScreenshotTestingMixin::HandleAnimationLoad() {
   timer_.Stop();
   content::BrowserThread::PostTask(
       content::BrowserThread::UI, FROM_HERE, animation_waiter_quitter_);
 }
 
 }  // namespace chromeos