Fixing std::swap(x, x) in base.

base/pickle_unittest.cc

Index: base/pickle_unittest.cc
diff --git a/base/pickle_unittest.cc b/base/pickle_unittest.cc
index e00edd9e03142b4dbc4509abc06df4062614327a..ebef1b9b3702e5399812b486c6ffd9b4388ac3fd 100644
--- a/base/pickle_unittest.cc
+++ b/base/pickle_unittest.cc
@@ -665,4 +665,9 @@ TEST(PickleTest, PickleSizer) {
   }
 }
 
+TEST(PickleTest, SelfSwap) {
+  TestingPickle pickle;
+  std::swap(pickle, pickle);
+}
+
 }  // namespace base