Use the mojo::shell namespace consistently underly shell/.

shell/application_manager/fetcher.cc

 // Copyright 2015 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 "shell/application_manager/fetcher.h"
 
 #include "url/gurl.h"
 
 namespace mojo {
+namespace shell {
 
 const char Fetcher::kMojoMagic[] = "#!mojo ";
 const size_t Fetcher::kMaxShebangLength = 2048;
 
 Fetcher::Fetcher(const FetchCallback& loader_callback)
     : loader_callback_(loader_callback) {
 }
 
 Fetcher::~Fetcher() {
 }
 
 bool Fetcher::PeekContentHandler(std::string* mojo_shebang,
                                  GURL* mojo_content_handler_url) {
   // TODO(aa): I guess this should just go in ApplicationManager now.
   std::string shebang;
   if (HasMojoMagic() && PeekFirstLine(&shebang)) {
     GURL url(shebang.substr(arraysize(kMojoMagic) - 1, std::string::npos));
     if (url.is_valid()) {
       *mojo_shebang = shebang;
       *mojo_content_handler_url = url;
       return true;
     }
   }
   return false;
 }
 
+}  // namespace shell
 }  // namespace mojo