Update from https://crrev.com/312398

shell/child_process_host.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 "shell/child_process_host.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 #include "shell/context.h"
 #include "shell/switches.h"
 
 namespace mojo {
 namespace shell {
 
 ChildProcessHost::ChildProcessHost(Context* context,
                                    Delegate* delegate,
                                    ChildProcess::Type type)
-    : context_(context),
-      delegate_(delegate),
-      type_(type),
-      child_process_handle_(base::kNullProcessHandle) {
+    : context_(context), delegate_(delegate), type_(type) {
   DCHECK(delegate);
   platform_channel_ = platform_channel_pair_.PassServerHandle();
   CHECK(platform_channel_.is_valid());
 }
 
 ChildProcessHost::~ChildProcessHost() {
-  if (child_process_handle_ != base::kNullProcessHandle) {
+  if (child_process_.IsValid()) {
     LOG(WARNING) << "Destroying ChildProcessHost with unjoined child";
-    base::CloseProcessHandle(child_process_handle_);
-    child_process_handle_ = base::kNullProcessHandle;
+    child_process_.Close();
   }
 }
 
 void ChildProcessHost::Start() {
-  DCHECK_EQ(child_process_handle_, base::kNullProcessHandle);
+  DCHECK(!child_process_.IsValid());
 
   delegate_->WillStart();
 
   CHECK(base::PostTaskAndReplyWithResult(
       context_->task_runners()->blocking_pool(), FROM_HERE,
       base::Bind(&ChildProcessHost::DoLaunch, base::Unretained(this)),
       base::Bind(&ChildProcessHost::DidLaunch, base::Unretained(this))));
 }
 
 int ChildProcessHost::Join() {
-  DCHECK_NE(child_process_handle_, base::kNullProcessHandle);
+  DCHECK(child_process_.IsValid());
   int rv = -1;
-  // Note: |WaitForExitCode()| closes the process handle.
-  LOG_IF(ERROR, !base::WaitForExitCode(child_process_handle_, &rv))
+  LOG_IF(ERROR, child_process_.WaitForExit(&rv))
       << "Failed to wait for child process";
-  child_process_handle_ = base::kNullProcessHandle;
+  child_process_.Close();
   return rv;
 }
 
 bool ChildProcessHost::DoLaunch() {
   static const char* kForwardSwitches[] = {
       switches::kTraceToConsole, switches::kV, switches::kVModule,
   };
 
   const base::CommandLine* parent_command_line =
       base::CommandLine::ForCurrentProcess();
   base::CommandLine child_command_line(parent_command_line->GetProgram());
   child_command_line.CopySwitchesFrom(*parent_command_line, kForwardSwitches,
                                       arraysize(kForwardSwitches));
   child_command_line.AppendSwitchASCII(
       switches::kChildProcessType, base::IntToString(static_cast<int>(type_)));
 
   embedder::HandlePassingInformation handle_passing_info;
   platform_channel_pair_.PrepareToPassClientHandleToChildProcess(
       &child_command_line, &handle_passing_info);
 
   base::LaunchOptions options;
 #if defined(OS_WIN)
   options.start_hidden = true;
   options.handles_to_inherit = &handle_passing_info;
 #elif defined(OS_POSIX)
   options.fds_to_remap = &handle_passing_info;
 #endif
-
-  if (!base::LaunchProcess(child_command_line, options, &child_process_handle_))
+  child_process_ = base::LaunchProcess(child_command_line, options);
+  if (!child_process_.IsValid())
     return false;
 
   platform_channel_pair_.ChildProcessLaunched();
   return true;
 }
 
 void ChildProcessHost::DidLaunch(bool success) {
   delegate_->DidStart(success);
 }
 
 }  // namespace shell
 }  // namespace mojo