Add QuicStringPiece which is actually StringPiece.

net/tools/quic/quic_http_response_cache_test.cc

 // Copyright 2013 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/tools/quic/quic_http_response_cache.h"
 
 #include "base/files/file_path.h"
 #include "base/path_service.h"
 #include "net/quic/platform/api/quic_map_util.h"
 #include "net/quic/platform/api/quic_str_cat.h"
 #include "net/quic/platform/api/quic_text_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-using base::StringPiece;
 using std::string;
 
 namespace net {
 namespace test {
 
 namespace {
 typedef QuicHttpResponseCache::Response Response;
 typedef QuicHttpResponseCache::ServerPushInfo ServerPushInfo;
 };  // namespace
 
@@ skipping 213 matching lines @@
     ASSERT_TRUE(QuicContainsKey(response->headers(), ":status"));
     EXPECT_EQ(push_response_status[i++],
               response->headers().find(":status")->second);
     EXPECT_EQ(push_resource.body, response->body());
     resources.pop_front();
   }
 }
 
 }  // namespace test
 }  // namespace net