[NaCl SDK] Add nacl_io and sdk_util namespaces.

native_client_sdk/src/libraries/nacl_io/kernel_object.h

Index: native_client_sdk/src/libraries/nacl_io/kernel_object.h
diff --git a/native_client_sdk/src/libraries/nacl_io/kernel_object.h b/native_client_sdk/src/libraries/nacl_io/kernel_object.h
index 99143b02e4e1b4bd16189502eaca2f47f678db20..414d34985cd43031ef985fd878f4ca8df3c7ba98 100644
--- a/native_client_sdk/src/libraries/nacl_io/kernel_object.h
+++ b/native_client_sdk/src/libraries/nacl_io/kernel_object.h
@@ -19,6 +19,7 @@
 
 #include "sdk_util/simple_lock.h"
 
+namespace nacl_io {
 
 // KernelObject provides basic functionality for threadsafe access to kernel
 // objects such as the CWD, mount points, file descriptors and file handles.
@@ -81,15 +82,17 @@ private:
   MountMap_t mounts_;
 
   // Lock to protect free_fds_ and handle_map_.
-  SimpleLock handle_lock_;
+  sdk_util::SimpleLock handle_lock_;
 
   // Lock to protect handle_map_.
-  SimpleLock mount_lock_;
+  sdk_util::SimpleLock mount_lock_;
 
   // Lock to protect cwd_.
-  SimpleLock cwd_lock_;
+  sdk_util::SimpleLock cwd_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(KernelObject);
 };
 
+}  // namespace nacl_io
+
 #endif  // LIBRARIES_NACL_IO_KERNEL_OBJECT_H_