Introduce the ability to wait for the watcher process to initialize.

chrome/app/chrome_watcher_client_win.cc

+// Copyright 2015 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 "chrome/app/chrome_watcher_client_win.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "components/browser_watcher/watcher_client_win.h"
+
+ChromeWatcherClient::ChromeWatcherClient(
+    const CommandLineGenerator& command_line_generator)
+    : command_line_generator_(command_line_generator) {
+}
+
+ChromeWatcherClient::~ChromeWatcherClient() {
+}
+
+bool ChromeWatcherClient::LaunchWatcher() {
+  // Create an inheritable event that the child process will signal when it has
+  // completed initialization.
+  SECURITY_ATTRIBUTES on_initialized_event_attributes = {
+      sizeof(SECURITY_ATTRIBUTES),  // nLength
+      nullptr,                      // lpSecurityDescriptor
+      TRUE                          // bInheritHandle
+  };
+  on_initialized_event_.Set(::CreateEvent(&on_initialized_event_attributes,
+                                          TRUE,  // manual reset
+                                          FALSE, nullptr));
+  if (!on_initialized_event_.IsValid()) {
+    PLOG(ERROR) << "Failed to create an event.";
+    return false;
+  }
+
+  // Configure the basic WatcherClient, binding in the initialization event
+  // HANDLE.
+  browser_watcher::WatcherClient watcher_client(
+      base::Bind(command_line_generator_, on_initialized_event_.Get()));
+  // Indicate that the event HANDLE should be inherited.
+  watcher_client.AddInheritedHandle(on_initialized_event_.Get());
+  // Launch the watcher.
+  watcher_client.LaunchWatcher();
+  // Grab a handle to the watcher so that we may later wait on its
+  // initialization.
+  process_ = watcher_client.process().Duplicate();
+  if (!process_.IsValid())
+    on_initialized_event_.Close();
+  return process_.IsValid();
+}
+
+bool ChromeWatcherClient::EnsureInitialized() {
+  if (!process_.IsValid()) {

[grt (UTC plus 2), 2015/02/04 03:04:48]

nit: no braces

[erikwright (departed), 2015/02/04 04:19:18]

Done.

+    return false;
+  }
+
+  DCHECK(on_initialized_event_.IsValid());
+
+  HANDLE handles[] = {on_initialized_event_.Get(), process_.Handle()};
+  DWORD result = ::WaitForMultipleObjects(arraysize(handles), handles,
+                                          FALSE, INFINITE);
+
+  switch (result) {
+    case WAIT_OBJECT_0:
+      return true;
+    case WAIT_OBJECT_0 + 1:
+      LOG(ERROR) << "Chrome watcher process failed to launch.";
+      return false;
+    case WAIT_FAILED:
+      PLOG(ERROR)
+          << "Failure while waiting on Chrome watcher process launch.";
+      return false;
+    default:
+      NOTREACHED() << "Unexpected result while waiting on Chrome watcher "
+                      "process launch: " << result;
+      return false;
+  }
+}
+
+bool ChromeWatcherClient::WaitForExit(int* exit_code) {
+  if (!process_.IsValid())
+    return false;
+
+  return process_.WaitForExit(exit_code);

[grt (UTC plus 2), 2015/02/04 03:04:47]

nit (here and below):
  return process_.IsValid() && ...;

[erikwright (departed), 2015/02/04 04:19:18]

Done.

+}
+
+bool ChromeWatcherClient::WaitForExitWithTimeout(const base::TimeDelta& timeout,
+                                                 int* exit_code) {
+  if (!process_.IsValid())
+    return false;
+
+  return process_.WaitForExitWithTimeout(timeout, exit_code);
+}