Use RecvMsgWithPid to find real PID for zygote children

content/common/child_process_sandbox_support_impl_linux.cc

 // Copyright (c) 2012 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 "content/common/child_process_sandbox_support_impl_linux.h"
 
 #include <sys/stat.h>
 
 #include "base/debug/trace_event.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/pickle.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/posix/unix_domain_socket_linux.h"
 #include "base/sys_byteorder.h"
 #include "content/common/sandbox_linux/sandbox_linux.h"
+#include "content/common/zygote_commands_linux.h"
 #include "third_party/WebKit/public/platform/linux/WebFontFamily.h"
 #include "third_party/WebKit/public/platform/linux/WebFontRenderStyle.h"
 
 namespace content {
 
 void GetFontFamilyForCharacter(int32_t character,
                                const char* preferred_locale,
                                blink::WebFontFamily* family) {
   TRACE_EVENT0("sandbox_ipc", "GetFontFamilyForCharacter");
 
@@ skipping 147 matching lines @@
     data_length = std::min(data_length, *output_length);
     ssize_t n = HANDLE_EINTR(pread(fd, output, data_length, data_offset));
     if (n != base::checked_cast<ssize_t>(data_length))
       return false;
   }
   *output_length = data_length;
 
   return true;
 }
 
+bool SendZygoteChildPing(int fd) {
+  return UnixDomainSocket::SendMsg(fd,
+                                   kZygoteChildPingMessage,
+                                   sizeof(kZygoteChildPingMessage),
+                                   std::vector<int>());
+}
+
 }  // namespace content