Move Singleton and related structs to namespace base

chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc

Index: chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc
diff --git a/chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc b/chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc
index c6096640b1f65e5436bd3743dd64ebe0cf0a6e30..ae5a0efc63b0dab9653526fc90f9803f5a0a12bb 100644
--- a/chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc
+++ b/chrome/browser/ui/views/apps/keyboard_hook_handler_win.cc
@@ -168,8 +168,8 @@ class LowLevelHookHandler {
 
  private:
   // Private constructor/destructor so it is accessible only
-  // DefaultSingletonTraits.
-  friend struct DefaultSingletonTraits<LowLevelHookHandler>;
+  // base::DefaultSingletonTraits.
+  friend struct base::DefaultSingletonTraits<LowLevelHookHandler>;
   LowLevelHookHandler();
 
   ~LowLevelHookHandler();
@@ -264,8 +264,8 @@ LRESULT CALLBACK LowLevelHookHandler::MessageFilterHook(int code,
 
 // static
 LowLevelHookHandler* LowLevelHookHandler::GetInstance() {
-  return Singleton<LowLevelHookHandler,
-                   DefaultSingletonTraits<LowLevelHookHandler>>::get();
+  return base::Singleton<LowLevelHookHandler, base::DefaultSingletonTraits<
+                                                  LowLevelHookHandler>>::get();
 }
 
 void LowLevelHookHandler::Register(HWND window_handle) {
@@ -416,8 +416,8 @@ LowLevelHookHandler::HandleKeyboardHook(int code,
 }  // namespace
 
 KeyboardHookHandler* KeyboardHookHandler::GetInstance() {
-  return Singleton<KeyboardHookHandler,
-                   DefaultSingletonTraits<KeyboardHookHandler>>::get();
+  return base::Singleton<KeyboardHookHandler, base::DefaultSingletonTraits<
+                                                  KeyboardHookHandler>>::get();
 }
 
 void KeyboardHookHandler::Register(views::Widget* widget) {