Improve multi-process debugging.

mojo/shell/switches.cc

Index: mojo/shell/switches.cc
diff --git a/mojo/shell/switches.cc b/mojo/shell/switches.cc
index 1fff40d5c3e2629addaf923447eaed15c2864bf5..e5c9d346c9bcb4c3c3ed1940266be011149159f6 100644
--- a/mojo/shell/switches.cc
+++ b/mojo/shell/switches.cc
@@ -8,6 +8,10 @@
 
 namespace switches {
 
+// Used just for debugging to make it easier to attach debuggers. The actual app
+// path that is used is sent over IPC.
+const char kApp[] = "app";
+
 // Used internally by the main process to indicate that a new process should be
 // a child process. Not for user use.
 const char kChildProcess[] = "child-process";