Turned on Shadow DOM flag by default.

content/renderer/render_thread_impl.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/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 684 matching lines @@
   WebRuntimeFeatures::enableFileSystem(
       !command_line.HasSwitch(switches::kDisableFileSystem));
 
   WebRuntimeFeatures::enableJavaScriptI18NAPI(
       !command_line.HasSwitch(switches::kDisableJavaScriptI18NAPI));
 
   WebRuntimeFeatures::enableGamepad(true);
 
   WebRuntimeFeatures::enableQuota(true);
 
-  WebRuntimeFeatures::enableShadowDOM(
-      command_line.HasSwitch(switches::kEnableExperimentalWebKitFeatures));
+  WebRuntimeFeatures::enableShadowDOM(true);
 
   WebRuntimeFeatures::enableStyleScoped(
       command_line.HasSwitch(switches::kEnableExperimentalWebKitFeatures));
 
   WebRuntimeFeatures::enableCSSExclusions(
       command_line.HasSwitch(switches::kEnableExperimentalWebKitFeatures));
 
   FOR_EACH_OBSERVER(RenderProcessObserver, observers_, WebKitInitialized());
 
   devtools_agent_message_filter_ = new DevToolsAgentFilter();
@@ skipping 433 matching lines @@
 
 scoped_refptr<base::MessageLoopProxy>
 RenderThreadImpl::GetFileThreadMessageLoopProxy() {
   DCHECK(message_loop() == MessageLoop::current());
   if (!file_thread_.get()) {
     file_thread_.reset(new base::Thread("Renderer::FILE"));
     file_thread_->Start();
   }
   return file_thread_->message_loop_proxy();
 }