[DevTools] Support multiple sessions in content/ domain handlers

content/browser/devtools/protocol/tracing_handler.cc

Index: content/browser/devtools/protocol/tracing_handler.cc
diff --git a/content/browser/devtools/protocol/tracing_handler.cc b/content/browser/devtools/protocol/tracing_handler.cc
index f522b3aa38ead5e781a4ece23cc4d082dab1e5e0..25d3a26918156464101d608e6eba82fa20dc94d5 100644
--- a/content/browser/devtools/protocol/tracing_handler.cc
+++ b/content/browser/devtools/protocol/tracing_handler.cc
@@ -131,9 +131,10 @@ TracingHandler::~TracingHandler() {
 }
 
 // static
-TracingHandler* TracingHandler::FromSession(DevToolsSession* session) {
-  return static_cast<TracingHandler*>(
-      session->GetHandlerByName(Tracing::Metainfo::domainName));
+std::vector<TracingHandler*> TracingHandler::ForAgentHost(
+    DevToolsAgentHostImpl* host) {
+  return DevToolsSession::HandlersForAgentHost<TracingHandler>(
+      host, Tracing::Metainfo::domainName);
 }
 
 void TracingHandler::Wire(UberDispatcher* dispatcher) {