[DevTools] Move subtargets functionality from ServiceWorker to Target domain.

content/browser/devtools/render_frame_devtools_agent_host.h

Index: content/browser/devtools/render_frame_devtools_agent_host.h
diff --git a/content/browser/devtools/render_frame_devtools_agent_host.h b/content/browser/devtools/render_frame_devtools_agent_host.h
index c7b1925ec514f09e2e31ca32de1c13514a00c45f..fbfb5f129fb0e0badbd1a87439b52b53cc74d42d 100644
--- a/content/browser/devtools/render_frame_devtools_agent_host.h
+++ b/content/browser/devtools/render_frame_devtools_agent_host.h
@@ -52,6 +52,7 @@ namespace schema { class SchemaHandler; }
 namespace security { class SecurityHandler; }
 namespace service_worker { class ServiceWorkerHandler; }
 namespace storage { class StorageHandler; }
+namespace target { class TargetHandler; }
 namespace tracing { class TracingHandler; }
 }
 
@@ -185,6 +186,7 @@ class CONTENT_EXPORT RenderFrameDevToolsAgentHost
       service_worker_handler_;
   std::unique_ptr<devtools::storage::StorageHandler>
       storage_handler_;
+  std::unique_ptr<devtools::target::TargetHandler> target_handler_;
   std::unique_ptr<devtools::tracing::TracingHandler> tracing_handler_;
   std::unique_ptr<devtools::emulation::EmulationHandler> emulation_handler_;
   std::unique_ptr<DevToolsFrameTraceRecorder> frame_trace_recorder_;