Make ChildProcessHost::DoLaunch() not touch a random set of things on a different thread.

shell/child_process_host_unittest.cc

Index: shell/child_process_host_unittest.cc
diff --git a/shell/child_process_host_unittest.cc b/shell/child_process_host_unittest.cc
index bb1817b5ee7b4472d79157a94dc76389a6a690fb..d4dc4a8f80de8cc9aa88b04f7ca2b331b4274771 100644
--- a/shell/child_process_host_unittest.cc
+++ b/shell/child_process_host_unittest.cc
@@ -25,9 +25,9 @@ class TestChildProcessHost : public ChildProcessHost {
   explicit TestChildProcessHost(Context* context) : ChildProcessHost(context) {}
   ~TestChildProcessHost() override {}
 
-  void DidStart(bool success) override {
-    EXPECT_TRUE(success);
-    ChildProcessHost::DidStart(success);
+  void DidStart(base::Process child_process) override {
+    EXPECT_TRUE(child_process.IsValid());
+    ChildProcessHost::DidStart(child_process.Pass());
     base::MessageLoop::current()->QuitWhenIdle();
   }