Move the remaning files in content\common to the content namespace.

content/common/message_router.h

Index: content/common/message_router.h
===================================================================
--- content/common/message_router.h	(revision 163632)
+++ content/common/message_router.h	(working copy)
@@ -27,6 +27,8 @@
 // The MessageRouter can be used as a concrete class provided its Send method
 // is not called and it does not receive any control messages.
 
+namespace content {
+
 class MessageRouter : public IPC::Listener, public IPC::Sender {
  public:
   MessageRouter();
@@ -59,4 +61,6 @@
   DISALLOW_COPY_AND_ASSIGN(MessageRouter);
 };
 
+}  // namespace content
+
 #endif  // CONTENT_COMMON_MESSAGE_ROUTER_H_