Let JsonDoubleQuote accept StringPiece

base/json/string_escape_unittest.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/json/string_escape.h"
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 namespace {
 
 const struct json_narrow_test_data {
   const char* to_escape;
   const char* escaped;
 } json_narrow_cases[] = {
   {"\b\001aZ\"\\wee", "\\b\\u0001aZ\\\"\\\\wee"},
   {"a\b\f\n\r\t\v\1\\.\"z",
       "a\\b\\f\\n\\r\\t\\u000B\\u0001\\\\.\\\"z"},
   {"b\x0f\x7f\xf0\xff!", "b\\u000F\\u007F\\u00F0\\u00FF!"},
   {"c<>d", "c\\u003C\\u003Ed"},
 };
 
 }  // namespace
 
 TEST(StringEscapeTest, JsonDoubleQuoteNarrow) {
   for (size_t i = 0; i < arraysize(json_narrow_cases); ++i) {
-    std::string in = json_narrow_cases[i].to_escape;
+    const char* in_ptr = json_narrow_cases[i].to_escape;
+    std::string in_str = in_ptr;
     std::string out;
-    JsonDoubleQuote(in, false, &out);
+    JsonDoubleQuote(in_ptr, false, &out);
+    EXPECT_EQ(std::string(json_narrow_cases[i].escaped), out);
+    out.erase();
+    JsonDoubleQuote(in_str, false, &out);
     EXPECT_EQ(std::string(json_narrow_cases[i].escaped), out);
   }
 
   std::string in = json_narrow_cases[0].to_escape;
   std::string out;
   JsonDoubleQuote(in, false, &out);
 
   // test quoting
   std::string out_quoted;
   JsonDoubleQuote(in, true, &out_quoted);
@@ skipping 50 matching lines @@
   null_prepend.push_back(0);
   in = null_prepend + in;
   std::string expected = "test\\u0000";
   expected += json_wide_cases[0].escaped;
   out.clear();
   JsonDoubleQuote(in, false, &out);
   EXPECT_EQ(expected, out);
 }
 
 }  // namespace base