Convert JsonWriter::Write to taking a const ref for the in-param

components/invalidation/invalidation_test_util.cc

Index: components/invalidation/invalidation_test_util.cc
diff --git a/components/invalidation/invalidation_test_util.cc b/components/invalidation/invalidation_test_util.cc
index 336879761e703f5f73aea37b16eac095cb866e9e..6fcd8efd3e04067be592c9355c90aa6c1a689824 100644
--- a/components/invalidation/invalidation_test_util.cc
+++ b/components/invalidation/invalidation_test_util.cc
@@ -99,9 +99,8 @@ void InvalidationEqMatcher::DescribeNegationTo(::std::ostream* os) const {
 }  // namespace
 
 void PrintTo(const AckHandle& ack_handle, ::std::ostream* os) {
-  scoped_ptr<base::Value> value(ack_handle.ToValue());
   std::string printable_ack_handle;
-  base::JSONWriter::Write(value.get(), &printable_ack_handle);
+  base::JSONWriter::Write(*ack_handle.ToValue(), &printable_ack_handle);
   *os << "{ ack_handle: " << printable_ack_handle << " }";
 }