[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/forwarding_agent_host.cc

Index: content/browser/devtools/forwarding_agent_host.cc
diff --git a/content/browser/devtools/forwarding_agent_host.cc b/content/browser/devtools/forwarding_agent_host.cc
index 98b89545dc99587abf6c3e9bdf58599db3b5a24e..d1847a2f607b5480b44d5e5bb95c229c27e837c6 100644
--- a/content/browser/devtools/forwarding_agent_host.cc
+++ b/content/browser/devtools/forwarding_agent_host.cc
@@ -29,15 +29,16 @@ void ForwardingAgentHost::ConnectionClosed() {
   HostClosed();
 }
 
-void ForwardingAgentHost::Attach() {
+void ForwardingAgentHost::AttachSession(DevToolsSession* session) {
   delegate_->Attach(this);
 }
 
-void ForwardingAgentHost::Detach() {
+void ForwardingAgentHost::DetachSession(int session_id) {
   delegate_->Detach();
 }
 
 bool ForwardingAgentHost::DispatchProtocolMessage(
+    DevToolsSession* session,
     const std::string& message) {
   delegate_->SendMessageToBackend(message);
   return true;