Always wait on subprocess in BrowserUiTest

Subprocesses spawned in the same process group with their parent are
killed when the parent test process exits. This CL makes BrowserUiTest
always wait on the subprocess so that those tests in the subprocess are
actually run.

Bug: 1128222, 688534, 1094369
Change-Id: I2ee1059fa4968be2c2c62a3834e5f70e883f7caf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2412690Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Keren Zhu <kerenzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#807160}

chrome/browser/ui/test/browser_ui_browsertest.cc

@@ -68,13 +68,9 @@ TEST(BrowserUiTest, Invoke) {
 
   base::LaunchOptions options;
 
-#if defined(OS_WIN)
-  // Under Windows, the child process won't launch without the wait option.
-  // See http://crbug.com/688534.
+  // Wait on subprocess. Otherwise the whole process group will be killed on
+  // parent process exit. See http://crbug.com/1094369.
   options.wait = true;
-#else
-  options.wait = !command.HasSwitch(switches::kTestLauncherInteractive);
-#endif
 
   base::LaunchProcess(command, options);
 }