Ensures the first browser in each interactive_ui_test is in the foreground

chrome/test/base/interactive_ui_tests_main.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/test/base/chrome_test_launcher.h"
 
 #include "build/build_config.h"
 #include "chrome/test/base/chrome_test_suite.h"
+#include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/interactive_test_utils.h"
 #include "ui/base/test/ui_controls.h"
 
 #if defined(USE_AURA)
 #include "ui/aura/test/ui_controls_factory_aura.h"
 #include "ui/base/test/ui_controls_aura.h"
 #if defined(OS_LINUX) && !defined(OS_CHROMEOS)
 #include "ui/views/test/ui_controls_factory_desktop_aurax11.h"
 #endif
 #endif
 
@@ skipping 53 matching lines @@
  public:
   int RunTestSuite(int argc, char** argv) override {
     return InteractiveUITestSuite(argc, argv).Run();
   }
 };
 
 int main(int argc, char** argv) {
 #if defined(OS_WIN)
   KillAlwaysOnTopWindows(RunType::BEFORE_TEST);
 #endif
+  // TODO(sky): this causes a crash in an autofill test on macosx, figure out
+  // why.

[msw, 2016/08/29 01:12:29]

nit: file a bug?

[sky, 2016/08/29 15:51:20]

Done.

+#if !defined(OS_MACOSX)
+  // Without this it's possible for the first browser to start up in the
+  // background, generally because the last test did something that causes the
+  // test to run in the background. Most interactive ui tests assume they are in
+  // the foreground and fail in weird ways if they aren't (for example, clicks
+  // go to the wrong place). This ensures the first browser is always in the
+  // foreground.
+  InProcessBrowserTest::set_global_browser_set_up_function(
+      &ui_test_utils::BringBrowserWindowToFront);

[msw, 2016/08/29 01:12:29]

It seems odd that new browser windows would ever be created in the background or
unactivated. Do we need a general fix for that? Otherwise, is it possible to
call this somewhere from the InteractiveUITestSuiteRunner or similar, to avoid
setting a function pointer?

[sky, 2016/08/29 15:51:20]

Interactive tests some times test behavior when clicking on the desktop. When
that happens the test launcher goes in the background. The next test that starts
is then launched in the background and we get the flake we were getting. In
other words I don't think it's unexpected that we need to do this, and you can
see some tests have calls to BringBrowserWindowToFront already.

+#endif
   // Run interactive_ui_tests serially, they do not support running in parallel.
   int default_jobs = 1;
   InteractiveUITestSuiteRunner runner;
   ChromeTestLauncherDelegate delegate(&runner);
   const int result = LaunchChromeTests(default_jobs, &delegate, argc, argv);
 #if defined(OS_WIN)
   KillAlwaysOnTopWindows(RunType::AFTER_TEST);
 #endif
   return result;
 }