Connect mojo:debugger to window_manager only when requested.

services/debugger/debugger.cc

Index: services/debugger/debugger.cc
diff --git a/services/debugger/debugger.cc b/services/debugger/debugger.cc
index 5d1f63038df94226aa76b10851818f167814ca2b..5654cdb2cf7434034bfad9d8e11f63f035a721e7 100644
--- a/services/debugger/debugger.cc
+++ b/services/debugger/debugger.cc
@@ -39,7 +39,6 @@ class Debugger : public mojo::ApplicationDelegate,
   // mojo::ApplicationDelegate:
   void Initialize(mojo::ApplicationImpl* app) override {
     app_ = app;
-    app->ConnectToService("mojo:window_manager", &window_manager_);
 
     // Format: --args-for="app_url command_port"
     if (app->args().size() < 2) {
@@ -47,6 +46,11 @@ class Debugger : public mojo::ApplicationDelegate,
       mojo::ApplicationImpl::Terminate();
       return;
     }
+    if (app->args().size() == 3 && app->args()[2] == "--wm") {
+      // Connect to window manager only if requested, as the user might want to
+      // run the debugger without spawning one.
+      app_->ConnectToService("mojo:window_manager", &window_manager_);
+    }
     base::StringToUint(app->args()[1], &command_port_);
     http_server::HttpServerFactoryPtr http_server_factory;
     app->ConnectToService("mojo:http_server", &http_server_factory);
@@ -129,6 +133,9 @@ class Debugger : public mojo::ApplicationDelegate,
   }
 
   void Reload() {
+    if (!window_manager_)
+      return;
+
     // SimpleWindowManager will wire up necessary services on our behalf.
     window_manager_->Embed(url_, nullptr, nullptr);
   }