update_engine: fix -Wpessimizing-move warning

BUG=chromium:492864
TEST=FEATURES="test" emerge-falco update_engine

Change-Id: Ia82d9ba6f65a6ad01e558d914dd2532968fcb97a
Reviewed-on: https://chromium-review.googlesource.com/273575
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Yunlian Jiang <yunlian@chromium.org>
Tested-by: Yunlian Jiang <yunlian@chromium.org>
diff --git a/update_manager/boxed_value_unittest.cc b/update_manager/boxed_value_unittest.cc
index 62f4bfe..4914a23 100644
--- a/update_manager/boxed_value_unittest.cc
+++ b/update_manager/boxed_value_unittest.cc
@@ -86,7 +86,7 @@
 
 TEST(UmBoxedValueTest, MixedMap) {
   map<int, BoxedValue> m;
-  m.emplace(42, std::move(BoxedValue(new const string("Hola mundo!"))));
+  m.emplace(42, BoxedValue(new const string("Hola mundo!")));
 
   auto it = m.find(42);
   ASSERT_NE(it, m.end());
diff --git a/update_manager/evaluation_context-inl.h b/update_manager/evaluation_context-inl.h
index 3255138..9dfed38 100644
--- a/update_manager/evaluation_context-inl.h
+++ b/update_manager/evaluation_context-inl.h
@@ -34,8 +34,7 @@
   // Cache the value for the next time. The map of CachedValues keeps the
   // ownership of the pointer until the map is destroyed.
   value_cache_.emplace(
-    static_cast<BaseVariable*>(var),
-    std::move(BoxedValue(result)));
+    static_cast<BaseVariable*>(var), BoxedValue(result));
   return result;
 }