[views-mus] Prevent creating a native OzonePlatform in mus tests.

ui/views/mus/views_mus_test_suite.cc

 // Copyright 2016 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 "ui/views/mus/views_mus_test_suite.h"
 
 #include <memory>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 234 matching lines @@
 
 void ViewsMusTestSuite::Initialize() {
   PlatformTestHelper::SetIsMus();
   // Let other services know that we're running in tests. Do this with a
   // command line flag to avoid making blocking calls to other processes for
   // setup for tests (e.g. to unlock the screen in the window manager).
   EnsureCommandLineSwitch(ui::switches::kUseTestConfig);
 
   EnsureCommandLineSwitch(switches::kOverrideUseSoftwareGLForTests);
 
+  // aura::Env detects whether it is being run as a mus client by looking for
+  // this flag. By setting this flag, we prevent the creation of an
+  // OzonePlatformX11 in mus client processes, which was previously causing
+  // false negatives, as the tests would pass because they were running against
+  // X11 and not mus.
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  command_line->AppendSwitch("primordial-pipe-token");

[sky, 2017/04/10 23:53:26]

This is mildly confusing and could easily confuse other things that look for
this switch. How about adding a private static bool indicating if in mus that
this code sets to true? AuraTestBase would explicitly friend ViewsMusTestSuite
as we don't want individual tests changing the state.

[Elliot Glaysher, 2017/04/12 18:09:16]

I've changed how mus works so that it no longer detects based on a command line
flag anywhere, and instead uses the Env::mode(). This requires some small
changes to how views tests work.

+
   ViewsTestSuite::Initialize();
   service_manager_connections_ = base::MakeUnique<ServiceManagerConnection>();
 }
 
 void ViewsMusTestSuite::Shutdown() {
   service_manager_connections_.reset();
   ViewsTestSuite::Shutdown();
 }
 
 }  // namespace views