Headless: Support sending and receiving of raw protocol messages

headless/lib/browser/headless_devtools_client_impl.cc

Index: headless/lib/browser/headless_devtools_client_impl.cc
diff --git a/headless/lib/browser/headless_devtools_client_impl.cc b/headless/lib/browser/headless_devtools_client_impl.cc
index ca315fa14a403cfd0b876dbb9653ec73591ac374..55b5ca9233c62ff8e142f5bb1cc14c4c16db5f43 100644
--- a/headless/lib/browser/headless_devtools_client_impl.cc
+++ b/headless/lib/browser/headless_devtools_client_impl.cc
@@ -31,6 +31,7 @@ HeadlessDevToolsClientImpl* HeadlessDevToolsClientImpl::From(
 
 HeadlessDevToolsClientImpl::HeadlessDevToolsClientImpl()
     : agent_host_(nullptr),
+      raw_protocol_listener_(nullptr),
       next_message_id_(0),
       renderer_crashed_(false),
       accessibility_domain_(this),
@@ -95,6 +96,29 @@ void HeadlessDevToolsClientImpl::DetachFromHost(
   pending_messages_.clear();
 }
 
+void HeadlessDevToolsClientImpl::SetRawProtocolListener(
+    RawProtocolListener* raw_protocol_listener) {
+  raw_protocol_listener_ = raw_protocol_listener;
+}
+
+void HeadlessDevToolsClientImpl::SendRawDevtoolsMessage(
+    const std::string& json_message) {
+#ifndef NDEBUG
+  std::unique_ptr<base::Value> message =
+      base::JSONReader::Read(json_message, base::JSON_PARSE_RFC);
+  const base::DictionaryValue* message_dict;
+  int id = 0;
+  if (!message || !message->GetAsDictionary(&message_dict) ||
+      !message_dict->GetInteger("id", &id)) {
+    NOTREACHED() << "Badly formed message";
+    return;
+  }
+  DCHECK_EQ((id % 2), 1) << "Raw devtools messages must have an odd ID.";

[Sami, 2017/04/12 14:54:24]

Could we instead add a generator getter for next_message_id_? That way this is
less error prone on the embedder side.

[alex clarke (OOO till 29th), 2017/04/13 10:46:28]

Added a function as discussed offline.

+#endif
+
+  agent_host_->DispatchProtocolMessage(this, json_message);
+}
+
 void HeadlessDevToolsClientImpl::DispatchProtocolMessage(
     content::DevToolsAgentHost* agent_host,
     const std::string& json_message) {
@@ -106,10 +130,12 @@ void HeadlessDevToolsClientImpl::DispatchProtocolMessage(
     NOTREACHED() << "Badly formed reply";
     return;
   }
-  if (!DispatchMessageReply(*message_dict) &&
-      !DispatchEvent(std::move(message), *message_dict)) {
-    DLOG(ERROR) << "Unhandled protocol message: " << json_message;
+  if (!DispatchMessageReply(*message_dict)) {
+    DispatchEvent(std::move(message), *message_dict);
+    // Silently ignore unhandled messages.
   }
+  if (raw_protocol_listener_)
+    raw_protocol_listener_->OnProtocolMessage(json_message, message_dict);
 }
 
 bool HeadlessDevToolsClientImpl::DispatchMessageReply(
@@ -314,7 +340,8 @@ void HeadlessDevToolsClientImpl::FinalizeAndSendMessage(
   if (renderer_crashed_)
     return;
   DCHECK(agent_host_);
-  int id = next_message_id_++;
+  int id = next_message_id_;
+  next_message_id_ += 2;  // We only send even numbered messages.
   message->SetInteger("id", id);
   std::string json_message;
   base::JSONWriter::Write(*message, &json_message);