Changing multiprocess test SpawnChild to return a struct.

base/debug/stack_trace_unittest.cc

Index: base/debug/stack_trace_unittest.cc
diff --git a/base/debug/stack_trace_unittest.cc b/base/debug/stack_trace_unittest.cc
index 560dc1ddde8dc5ee7dd42e62b0e0e296ad5a5ac4..bbcf388376a602733519d3100cdeb761ffb3bcce 100644
--- a/base/debug/stack_trace_unittest.cc
+++ b/base/debug/stack_trace_unittest.cc
@@ -171,11 +171,11 @@ MULTIPROCESS_TEST_MAIN(MismatchedMallocChildProcess) {
 // and e.g. mismatched new[]/delete would cause a hang because
 // of re-entering malloc.
 TEST_F(StackTraceTest, AsyncSignalUnsafeSignalHandlerHang) {
-  Process child = SpawnChild("MismatchedMallocChildProcess");
-  ASSERT_TRUE(child.IsValid());
+  SpawnChildResult spawn_result = SpawnChild("MismatchedMallocChildProcess");
+  ASSERT_TRUE(spawn_result.process.IsValid());
   int exit_code;
-  ASSERT_TRUE(child.WaitForExitWithTimeout(TestTimeouts::action_timeout(),
-                                           &exit_code));
+  ASSERT_TRUE(spawn_result.process.WaitForExitWithTimeout(
+      TestTimeouts::action_timeout(), &exit_code));
 }
 #endif  // !defined(OS_IOS)