Make it possible to pass a default url to sky_debugger

sky/tools/debugger/prompt/prompt.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/debug/profiler.h"
 #include "base/memory/weak_ptr.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 24 matching lines @@
       : is_tracing_(false),
         weak_ptr_factory_(this) {
   }
   virtual ~Prompt() {
   }
 
  private:
   // Overridden from mojo::ApplicationDelegate:
   virtual void Initialize(mojo::ApplicationImpl* app) override {
     app->ConnectToService("mojo:tracing", &tracing_);
-    // app_url, command_port, url_to_load
+    // Format: --args-for="app_url command_port"
     if (app->args().size() < 2) {
       LOG(ERROR) << "--args-for required to specify command_port";
-      exit(2);
+      mojo::ApplicationImpl::Terminate();
+      return;
     }
 
     base::StringToUint(app->args()[1], &command_port_);
 
     scoped_ptr<net::ServerSocket> server_socket(
         new net::TCPServerSocket(NULL, net::NetLog::Source()));
     int result = server_socket->ListenWithAddressAndPort("0.0.0.0", command_port_, 1);
     if (result != net::OK) {
-      // FIXME: Should we quit here?
       LOG(ERROR) << "Failed to bind to port " << command_port_
-                 << " skydb commands will not work, exiting.";
-      exit(2);
+                 << " skydb commands will not work.";
+      mojo::ApplicationImpl::Terminate();
       return;
     }
     web_server_.reset(new net::HttpServer(server_socket.Pass(), this));
   }
 
   virtual bool ConfigureIncomingConnection(
       mojo::ApplicationConnection* connection) override {
     connection->ConnectToService(&debugger_);
     return true;
   }
@@ skipping 143 matching lines @@
 };
 
 }  // namespace debugger
 }  // namespace sky
 
 MojoResult MojoMain(MojoHandle shell_handle) {
   mojo::ApplicationRunnerChromium runner(new sky::debugger::Prompt);
   runner.set_message_loop_type(base::MessageLoop::TYPE_IO);
   return runner.Run(shell_handle);
 }