DevTools: introduce browser domain for basic target discovery.

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 2f662bb669550ec6b7ff2e075844fddebd0c4f66..1b18b2fb4939919c137bca42d53270b16560d3bf 100644
--- a/headless/lib/browser/headless_devtools_client_impl.cc
+++ b/headless/lib/browser/headless_devtools_client_impl.cc
@@ -72,7 +72,7 @@ void HeadlessDevToolsClientImpl::AttachToHost(
 void HeadlessDevToolsClientImpl::DetachFromHost(
     content::DevToolsAgentHost* agent_host) {
   DCHECK_EQ(agent_host_, agent_host);
-  agent_host_->DetachClient();
+  agent_host_->DetachClient(this);
   agent_host_ = nullptr;
   pending_messages_.clear();
 }