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

net/spdy/spdy_protocol.cc

Index: net/spdy/spdy_protocol.cc
diff --git a/net/spdy/spdy_protocol.cc b/net/spdy/spdy_protocol.cc
index 435c8417b2cf36be9aaaf98eb8641031eb5673b0..7d287cafc081ff0fed99fd21548da0c93307c833 100644
--- a/net/spdy/spdy_protocol.cc
+++ b/net/spdy/spdy_protocol.cc
@@ -228,9 +228,9 @@ SpdyDataIR::SpdyDataIR(SpdyStreamId stream_id, SpdyStringPiece data)
 SpdyDataIR::SpdyDataIR(SpdyStreamId stream_id, const char* data)
     : SpdyDataIR(stream_id, SpdyStringPiece(data)) {}
 
-SpdyDataIR::SpdyDataIR(SpdyStreamId stream_id, std::string data)
+SpdyDataIR::SpdyDataIR(SpdyStreamId stream_id, SpdyString data)
     : SpdyFrameWithFinIR(stream_id),
-      data_store_(base::MakeUnique<std::string>(std::move(data))),
+      data_store_(base::MakeUnique<SpdyString>(std::move(data))),
       data_(data_store_->data()),
       data_len_(data_store_->size()),
       padded_(false),
@@ -306,7 +306,7 @@ SpdyGoAwayIR::SpdyGoAwayIR(SpdyStreamId last_good_stream_id,
 
 SpdyGoAwayIR::SpdyGoAwayIR(SpdyStreamId last_good_stream_id,
                            SpdyErrorCode error_code,
-                           std::string description)
+                           SpdyString description)
     : description_store_(std::move(description)),
       description_(description_store_) {
   set_last_good_stream_id(last_good_stream_id);
@@ -325,7 +325,7 @@ SpdyFrameType SpdyGoAwayIR::frame_type() const {
 
 SpdyContinuationIR::SpdyContinuationIR(SpdyStreamId stream_id)
     : SpdyFrameWithStreamIdIR(stream_id), end_headers_(false) {
-  encoding_ = base::MakeUnique<std::string>();
+  encoding_ = base::MakeUnique<SpdyString>();
 }
 
 SpdyContinuationIR::~SpdyContinuationIR() {}