update_engine: Replace scoped_ptr with std::unique_ptr.

BUG=None
TEST=`FEATURES=test emerge-$BOARD update_engine`
TEST=`USE='clang asan' FEATURES=test emerge-$BOARD update_engine`

Change-Id: I55a2f7f53675faaac20ba25f72ed52cf938d7744
Reviewed-on: https://chromium-review.googlesource.com/224189
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Ben Chan <benchan@chromium.org>
diff --git a/update_manager/fake_variable.h b/update_manager/fake_variable.h
index 2dae3db..9459fac 100644
--- a/update_manager/fake_variable.h
+++ b/update_manager/fake_variable.h
@@ -5,10 +5,9 @@
 #ifndef UPDATE_ENGINE_UPDATE_MANAGER_FAKE_VARIABLE_H_
 #define UPDATE_ENGINE_UPDATE_MANAGER_FAKE_VARIABLE_H_
 
+#include <memory>
 #include <string>
 
-#include <base/memory/scoped_ptr.h>
-
 #include "update_engine/update_manager/variable.h"
 
 namespace chromeos_update_manager {
@@ -53,7 +52,7 @@
 
  private:
   // The pointer returned by GetValue().
-  scoped_ptr<const T> ptr_;
+  std::unique_ptr<const T> ptr_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeVariable);
 };