Add SpdyString alias for std::string in net/spdy.

net/spdy/spdy_log_util_unittest.cc

 // Copyright 2017 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 "net/spdy/spdy_log_util.h"
 
 #include "base/values.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace net {
 
 TEST(SpdyLogUtilTest, ElideGoAwayDebugDataForNetLog) {
   // Only elide for appropriate log level.
   EXPECT_EQ(
       "[6 bytes were stripped]",
       ElideGoAwayDebugDataForNetLog(NetLogCaptureMode::Default(), "foobar"));
   EXPECT_EQ("foobar",
             ElideGoAwayDebugDataForNetLog(
                 NetLogCaptureMode::IncludeCookiesAndCredentials(), "foobar"));
 }
 
 TEST(SpdyLogUtilTest, ElideSpdyHeaderBlockForNetLog) {
   SpdyHeaderBlock headers;
   headers["foo"] = "bar";
   headers["cookie"] = "name=value";
 
   std::unique_ptr<base::ListValue> list =
       ElideSpdyHeaderBlockForNetLog(headers, NetLogCaptureMode::Default());
   EXPECT_EQ(2u, list->GetSize());
-  std::string field;
+  SpdyString field;
   EXPECT_TRUE(list->GetString(0, &field));
   EXPECT_EQ("foo: bar", field);
   EXPECT_TRUE(list->GetString(1, &field));
   EXPECT_EQ("cookie: [10 bytes were stripped]", field);
 
   list = ElideSpdyHeaderBlockForNetLog(
       headers, NetLogCaptureMode::IncludeCookiesAndCredentials());
   EXPECT_EQ(2u, list->GetSize());
   EXPECT_TRUE(list->GetString(0, &field));
   EXPECT_EQ("foo: bar", field);
   EXPECT_TRUE(list->GetString(1, &field));
   EXPECT_EQ("cookie: name=value", field);
 }
 
 }  // namespace net