content/browser: Move more files into the content namespace.

content/browser/system_message_window_win.h

Index: content/browser/system_message_window_win.h
diff --git a/content/browser/system_message_window_win.h b/content/browser/system_message_window_win.h
index d4120c9c38927cea658e5fbcc7d1b2d03eb0102d..b29bad57c896de573dd874b04bfafbdce5964f09 100644
--- a/content/browser/system_message_window_win.h
+++ b/content/browser/system_message_window_win.h
@@ -11,6 +11,8 @@
 #include "base/memory/scoped_ptr.h"
 #include "content/common/content_export.h"
 
+namespace content {
+
 class CONTENT_EXPORT SystemMessageWindowWin {
  public:
   SystemMessageWindowWin();
@@ -44,4 +46,6 @@ class CONTENT_EXPORT SystemMessageWindowWin {
   DISALLOW_COPY_AND_ASSIGN(SystemMessageWindowWin);
 };
 
+}  // namespace content
+
 #endif  // CONTENT_BROWSER_SYSTEM_MESSAGE_WINDOW_WIN_H_