Use Chromium BUILD to approximate Blimp protocol version, and check it.

blimp/net/blimp_connection.cc

Index: blimp/net/blimp_connection.cc
diff --git a/blimp/net/blimp_connection.cc b/blimp/net/blimp_connection.cc
index 7b79a5f3f9dc229258372d0fee0bea972600a23f..51da7d9920bc04ce4c8e69191f5eb2b6681147f1 100644
--- a/blimp/net/blimp_connection.cc
+++ b/blimp/net/blimp_connection.cc
@@ -105,12 +105,58 @@ void BlimpMessageSender::OnWritePacketComplete(int result) {
   process_callback.Run(result);
 }
 
+// MessageProcessor filter used to route EndConnection messages through to
+// OnConnectionError notifications on the owning BlimpConnection.
+class BlimpConnection::EndConnectionFilter : public BlimpMessageProcessor {
+ public:
+  explicit EndConnectionFilter(BlimpConnection* connection);
+
+  void set_message_handler(BlimpMessageProcessor* message_handler) {
+    message_handler_ = message_handler;
+  }
+
+  // BlimpMessageProcessor implementation.
+  void ProcessMessage(std::unique_ptr<BlimpMessage> message,
+                      const net::CompletionCallback& callback) override;
+
+ private:
+  // Owning BlimpConnection, on which to call OnConnectionError.
+  BlimpConnection* connection_;
+
+  // Caller-provided message handler to forward non-EndConnection messages to.
+  BlimpMessageProcessor* message_handler_;
+
+  DISALLOW_COPY_AND_ASSIGN(EndConnectionFilter);
+};
+
+BlimpConnection::EndConnectionFilter::EndConnectionFilter(
+    BlimpConnection* connection)
+    : connection_(connection), message_handler_(nullptr) {}
+
+void BlimpConnection::EndConnectionFilter::ProcessMessage(
+    std::unique_ptr<BlimpMessage> message,
+    const net::CompletionCallback& callback) {
+  if (message->has_protocol_control() &&
+      message->protocol_control().has_end_connection()) {
+    // Report the EndConnection reason to connection error observers.
+    connection_->OnConnectionError(
+        message->protocol_control().end_connection().reason());
+
+    // Caller must ensure |callback| safe to call after OnConnectionError.
+    callback.Run(message->protocol_control().end_connection().reason());
+    return;
+  }
+
+  message_handler_->ProcessMessage(std::move(message), callback);
+}
+
 BlimpConnection::BlimpConnection(std::unique_ptr<PacketReader> reader,
                                  std::unique_ptr<PacketWriter> writer)
     : reader_(std::move(reader)),
       message_pump_(new BlimpMessagePump(reader_.get())),
       writer_(std::move(writer)),
-      outgoing_msg_processor_(new BlimpMessageSender(writer_.get())) {
+      outgoing_msg_processor_(new BlimpMessageSender(writer_.get())),
+      end_connection_filter_(new EndConnectionFilter(this)) {
   DCHECK(writer_);
   DCHECK(reader_);
 
@@ -136,7 +182,9 @@ void BlimpConnection::RemoveConnectionErrorObserver(
 
 void BlimpConnection::SetIncomingMessageProcessor(
     BlimpMessageProcessor* processor) {
-  message_pump_->SetMessageProcessor(processor);
+  end_connection_filter_->set_message_handler(processor);
+  message_pump_->SetMessageProcessor(processor ? end_connection_filter_.get()
+                                               : nullptr);
 }
 
 BlimpMessageProcessor* BlimpConnection::GetOutgoingMessageProcessor() {