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

chrome/test/chromedriver/server/http_handler_unittest.cc

Index: chrome/test/chromedriver/server/http_handler_unittest.cc
diff --git a/chrome/test/chromedriver/server/http_handler_unittest.cc b/chrome/test/chromedriver/server/http_handler_unittest.cc
index 55eaeb73d7ba8707475daf49fc438261d7e7be13..59c191f3c22966ab59d9599f164c7ddc9e094dc7 100644
--- a/chrome/test/chromedriver/server/http_handler_unittest.cc
+++ b/chrome/test/chromedriver/server/http_handler_unittest.cc
@@ -74,7 +74,7 @@ TEST(HttpHandlerTest, HandleNewSession) {
   body.SetInteger("value", 1);
   body.SetString("sessionId", "session_id");
   std::string json;
-  base::JSONWriter::Write(&body, &json);
+  base::JSONWriter::Write(body, &json);
   ASSERT_EQ(json, response.body());
 }
 
@@ -119,7 +119,7 @@ TEST(HttpHandlerTest, HandleCommand) {
   body.SetInteger("value", 1);
   body.SetString("sessionId", "session_id");
   std::string json;
-  base::JSONWriter::Write(&body, &json);
+  base::JSONWriter::Write(body, &json);
   ASSERT_EQ(json, response.body());
 }