Changing multiprocess test SpawnChild to return a struct.

mojo/edk/test/multiprocess_test_helper.h

Index: mojo/edk/test/multiprocess_test_helper.h
diff --git a/mojo/edk/test/multiprocess_test_helper.h b/mojo/edk/test/multiprocess_test_helper.h
index dd9bd6a623b31345f9208a18f7436b0ae382c745..c3b6e01c797a801d2824b2254da5cc51480280fe 100644
--- a/mojo/edk/test/multiprocess_test_helper.h
+++ b/mojo/edk/test/multiprocess_test_helper.h
@@ -80,7 +80,7 @@ class MultiprocessTestHelper {
   // |EXPECT_TRUE(WaitForChildTestShutdown());|.
   bool WaitForChildTestShutdown();
 
-  const base::Process& test_child() const { return test_child_; }
+  const base::Process& test_child() const { return test_child_.process; }
 
   // Used by macros in mojo/edk/test/mojo_test_base.h to support multiprocess
   // test client initialization.
@@ -93,7 +93,7 @@ class MultiprocessTestHelper {
 
  private:
   // Valid after |StartChild()| and before |WaitForChildShutdown()|.
-  base::Process test_child_;
+  base::SpawnChildResult test_child_;
 
   ProcessErrorCallback process_error_callback_;