[sessions] Properly namespace recently-componentized TabRestore code

components/sessions/core/tab_restore_service.cc

Index: components/sessions/core/tab_restore_service.cc
diff --git a/components/sessions/core/tab_restore_service.cc b/components/sessions/core/tab_restore_service.cc
index 6d33f35dd2d5606f0e5649bf17c8ec1afc5885fa..7fccf96c56e30a8e4f7579c62af851a08f848561 100644
--- a/components/sessions/core/tab_restore_service.cc
+++ b/components/sessions/core/tab_restore_service.cc
@@ -4,6 +4,8 @@
 
 #include "components/sessions/core/tab_restore_service.h"
 
+namespace sessions {
+
 // TimeFactory-----------------------------------------------------------------
 
 TabRestoreService::TimeFactory::~TimeFactory() {}
@@ -79,3 +81,5 @@ TabRestoreService::Window::~Window() {
 
 TabRestoreService::~TabRestoreService() {
 }
+
+}  // namespace sessions