MultiProcessTest: Update SpawnChild* to return a Process.

content/common/sandbox_mac_unittest_helper.mm

Index: content/common/sandbox_mac_unittest_helper.mm
diff --git a/content/common/sandbox_mac_unittest_helper.mm b/content/common/sandbox_mac_unittest_helper.mm
index faac7ae21d1659170bef5b49bb4c1fbb72a05fb9..cb029d146e1c2b04e23057c812ef4dd6a720ca00 100644
--- a/content/common/sandbox_mac_unittest_helper.mm
+++ b/content/common/sandbox_mac_unittest_helper.mm
@@ -77,14 +77,14 @@ bool MacSandboxTest::RunTestInSandbox(SandboxType sandbox_type,
   if (test_data)
     setenv(kTestDataKey, test_data, 1);
 
-  base::ProcessHandle child_process = SpawnChild("mac_sandbox_test_runner");
-  if (child_process == base::kNullProcessHandle) {
+  base::Process child_process = SpawnChild("mac_sandbox_test_runner");
+  if (!child_process.IsValid()) {
     LOG(WARNING) << "SpawnChild failed";
     return false;
   }
   int code = -1;
-  if (!base::WaitForExitCode(child_process, &code)) {
-    LOG(WARNING) << "base::WaitForExitCode failed";
+  if (!child_process.WaitForExit(&code)) {
+    LOG(WARNING) << "Process::WaitForExit failed";
     return false;
   }
   return code == 0;