Revert of Remove EnableThreadedCompositing from the browser.

content/shell/app/shell_main_delegate.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/shell/app/shell_main_delegate.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/cpu.h"
 #include "base/files/file.h"
@@ skipping 139 matching lines @@
 #endif
 
     if (!command_line.HasSwitch(switches::kStableReleaseMode)) {
       command_line.AppendSwitch(
         switches::kEnableExperimentalWebPlatformFeatures);
     }
 
     if (!command_line.HasSwitch(switches::kEnableThreadedCompositing)) {
       command_line.AppendSwitch(switches::kDisableThreadedCompositing);
       command_line.AppendSwitch(cc::switches::kDisableThreadedAnimation);
-      command_line.AppendSwitch(switches::kDisableImplSidePainting);
     }
 
     command_line.AppendSwitch(switches::kEnableInbandTextTracks);
     command_line.AppendSwitch(switches::kMuteAudio);
 
 #if defined(USE_AURA) || defined(OS_ANDROID)
     // TODO: crbug.com/311404 Make layout tests work w/ delegated renderer.
     command_line.AppendSwitch(switches::kDisableDelegatedRenderer);
     command_line.AppendSwitch(cc::switches::kCompositeToMailbox);
 #endif
@@ skipping 125 matching lines @@
   browser_client_.reset(new ShellContentBrowserClient);
   return browser_client_.get();
 }
 
 ContentRendererClient* ShellMainDelegate::CreateContentRendererClient() {
   renderer_client_.reset(new ShellContentRendererClient);
   return renderer_client_.get();
 }
 
 }  // namespace content