Implement Drain() on HttpPipelinedStream.

net/http/http_pipelined_stream.cc

Index: net/http/http_pipelined_stream.cc
diff --git a/net/http/http_pipelined_stream.cc b/net/http/http_pipelined_stream.cc
index 6b844a6210ddae7eb0f3ca8d16c29fe9d6c290af..943c2c085763f408c83d29edc2f4ef7dd07e3f60 100644
--- a/net/http/http_pipelined_stream.cc
+++ b/net/http/http_pipelined_stream.cc
@@ -118,11 +118,8 @@ void HttpPipelinedStream::LogNumRttVsBytesMetrics() const {
   // TODO(simonjam): I don't want to copy & paste this from http_basic_stream.
 }
 
-void HttpPipelinedStream::Drain(HttpNetworkSession*) {
-  // On errors, we already evict everything from the pipeline and close it.
-  // TODO(simonjam): Consider trying to drain the pipeline in the same way that
-  // HttpBasicStream does.
-  delete this;
+void HttpPipelinedStream::Drain(HttpNetworkSession* session) {
+  pipeline_->Drain(this, session);
 }
 
 const SSLConfig& HttpPipelinedStream::used_ssl_config() const {