Put PrintingUIWebContentsObserver and PrintingMessageFilter into printing namespace.

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 784 matching lines @@
   Profile* profile = Profile::FromBrowserContext(host->GetBrowserContext());
   net::URLRequestContextGetter* context =
       profile->GetRequestContextForRenderProcess(id);
 
   host->AddFilter(new ChromeRenderMessageFilter(id, profile));
 #if defined(ENABLE_PLUGINS)
   host->AddFilter(new PluginInfoMessageFilter(id, profile));
 #endif
   host->AddFilter(new cast::CastTransportHostFilter);
 #if defined(ENABLE_PRINTING)
-  host->AddFilter(new PrintingMessageFilter(id, profile));
+  host->AddFilter(new printing::PrintingMessageFilter(id, profile));
 #endif
   host->AddFilter(new SearchProviderInstallStateMessageFilter(id, profile));
 #if defined(ENABLE_SPELLCHECK)
   host->AddFilter(new SpellCheckMessageFilter(id));
 #endif
 #if defined(OS_MACOSX)
   host->AddFilter(new SpellCheckMessageFilterMac(id));
 #endif
   host->AddFilter(new ChromeNetBenchmarkingMessageFilter(profile, context));
   host->AddFilter(new prerender::PrerenderMessageFilter(id, profile));
@@ skipping 1798 matching lines @@
       switches::kDisableWebRtcEncryption,
     };
     to_command_line->CopySwitchesFrom(from_command_line,
                                       kWebRtcDevSwitchNames,
                                       arraysize(kWebRtcDevSwitchNames));
   }
 }
 #endif  // defined(ENABLE_WEBRTC)
 
 }  // namespace chrome