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

net/BUILD.gn

 # Copyright (c) 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.
 
 import("//build/buildflag_header.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
@@ skipping 1501 matching lines @@
       "spdy/hpack/hpack_static_table.h",
       "spdy/http2_frame_decoder_adapter.cc",
       "spdy/http2_frame_decoder_adapter.h",
       "spdy/http2_priority_dependencies.cc",
       "spdy/http2_priority_dependencies.h",
       "spdy/multiplexed_http_stream.cc",
       "spdy/multiplexed_http_stream.h",
       "spdy/multiplexed_session.cc",
       "spdy/multiplexed_session.h",
       "spdy/platform/api/spdy_estimate_memory_usage.h",
+      "spdy/platform/api/spdy_string.h",
       "spdy/platform/api/spdy_string_piece.h",
       "spdy/platform/api/spdy_string_utils.h",
       "spdy/platform/impl/spdy_estimate_memory_usage_impl.h",
+      "spdy/platform/impl/spdy_string_impl.h",
       "spdy/platform/impl/spdy_string_piece_impl.h",
       "spdy/platform/impl/spdy_string_utils_impl.h",
       "spdy/priority_write_scheduler.h",
       "spdy/server_push_delegate.h",
       "spdy/spdy_alt_svc_wire_format.cc",
       "spdy/spdy_alt_svc_wire_format.h",
       "spdy/spdy_bitmasks.h",
       "spdy/spdy_buffer.cc",
       "spdy/spdy_buffer.h",
       "spdy/spdy_buffer_producer.cc",
@@ skipping 4176 matching lines @@
   ]
   deps = [
     ":net_fuzzer_test_support",
     ":test_support",
     "//base",
     "//net",
   ]
   dict = "data/fuzzer_dictionaries/net_spdy_session_fuzzer.dict"
   seed_corpus = "data/fuzzer_data/net_spdy_session_fuzzer/"
 }