Enable shadow DOM-based "missing plugin" placeholder.

chrome/browser/chrome_content_browser_client.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 "chrome/browser/chrome_content_browser_client.h"
 
 #include <set>
 #include <utility>
 #include <vector>
 
@@ skipping 1347 matching lines @@
       switches::kCloudPrintURL,
       switches::kCloudPrintXmppEndpoint,
       switches::kDisableBundledPpapiFlash,
       switches::kEnableBenchmarking,
       switches::kEnableNaCl,
 #if !defined(DISABLE_NACL)
       switches::kEnableNaClDebug,
       switches::kEnableNaClNonSfiMode,
 #endif
       switches::kEnableNetBenchmarking,
+      switches::kEnablePluginPlaceholderShadowDom,
       switches::kEnableShowModalDialog,
       switches::kEnableStreamlinedHostedApps,
       switches::kEnableWebBasedSignin,
       switches::kJavaScriptHarmony,
       switches::kMessageLoopHistogrammer,
       switches::kOutOfProcessPdf,
       switches::kPlaybackMode,
       switches::kPpapiFlashArgs,
       switches::kPpapiFlashPath,
       switches::kPpapiFlashVersion,
@@ skipping 1271 matching lines @@
       switches::kDisableWebRtcEncryption,
     };
     to_command_line->CopySwitchesFrom(from_command_line,
                                       kWebRtcDevSwitchNames,
                                       arraysize(kWebRtcDevSwitchNames));
   }
 }
 #endif  // defined(ENABLE_WEBRTC)
 
 }  // namespace chrome