Add pause/resume for isolates in vmservice/observatory.

runtime/bin/dbg_connection.h

Index: runtime/bin/dbg_connection.h
diff --git a/runtime/bin/dbg_connection.h b/runtime/bin/dbg_connection.h
index 8fd0860a5a57ba1071c1a3de42c9b305c50542c4..4d2d6feb66d26eac9cf98842a93eeca18f74fbe5 100644
--- a/runtime/bin/dbg_connection.h
+++ b/runtime/bin/dbg_connection.h
@@ -51,6 +51,11 @@ class DebuggerConnectionHandler {
   // from the client.
   static int StartHandler(const char* address, int port_number);
 
+  // Initializes the parts of the debugger which are needed by the vm
+  // service.  This function should only be called when StartHandler
+  // is not called.
+  static void InitForVmService();
+
   // Called by Isolates when they need to wait for a connection
   // from debugger clients.
   static void WaitForConnection();