Improve process launch handle sharing API.

base/process/launch_fuchsia.cc

 // Copyright 2017 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 "base/process/launch.h"
 
 #include <launchpad/launchpad.h>
 #include <magenta/process.h>
 #include <unistd.h>
 
@@ skipping 98 matching lines @@
   }
 
   if (!environ_modifications.empty())
     new_environ = AlterEnvironment(old_environ, environ_modifications);
 
   if (!environ_modifications.empty() || options.clear_environ)
     launchpad_set_environ(lp, new_environ.get());
   else
     to_clone |= LP_CLONE_ENVIRON;
 
-  if (!options.fds_to_remap)
+  if (options.fds_to_remap.empty())
     to_clone |= LP_CLONE_MXIO_STDIO;
   launchpad_clone(lp, to_clone);
 
-  if (options.fds_to_remap) {
-    for (const auto& src_target : *options.fds_to_remap) {
-      launchpad_clone_fd(lp, src_target.first, src_target.second);
-    }
-  }
+  for (const auto& src_target : options.fds_to_remap)
+    launchpad_clone_fd(lp, src_target.first, src_target.second);
 
   mx_handle_t proc;
   const char* errmsg;
   mx_status_t status = launchpad_go(lp, &proc, &errmsg);
   if (status != MX_OK) {
     LOG(ERROR) << "launchpad_go failed: " << errmsg << ", status=" << status;
     return Process();
   }
 
   return Process(proc);
@@ skipping 21 matching lines @@
 }
 
 bool GetAppOutputWithExitCode(const CommandLine& cl,
                               std::string* output,
                               int* exit_code) {
   bool result = GetAppOutputInternal(cl.argv(), false, output, exit_code);
   return result && *exit_code == EXIT_SUCCESS;
 }
 
 }  // namespace base