Revert 164120 - content/browser: Move more files into the content namespace.

content/browser/mime_registry_message_filter.cc

Index: content/browser/mime_registry_message_filter.cc
===================================================================
--- content/browser/mime_registry_message_filter.cc	(revision 164121)
+++ content/browser/mime_registry_message_filter.cc	(working copy)
@@ -7,7 +7,7 @@
 #include "content/common/mime_registry_messages.h"
 #include "net/base/mime_util.h"
 
-namespace content {
+using content::BrowserThread;
 
 MimeRegistryMessageFilter::MimeRegistryMessageFilter() {
 }
@@ -51,5 +51,3 @@
     const std::string& mime_type, FilePath::StringType* extension) {
   net::GetPreferredExtensionForMimeType(mime_type, extension);
 }
-
-}  // namespace content