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

ui/views/mus/views_mus_test_suite.cc

Index: ui/views/mus/views_mus_test_suite.cc
diff --git a/ui/views/mus/views_mus_test_suite.cc b/ui/views/mus/views_mus_test_suite.cc
index 86b748839e150b88e1a10d9660706f8e3478087a..829d0d460c6a6684c2f48c7821b1264751e26f3f 100644
--- a/ui/views/mus/views_mus_test_suite.cc
+++ b/ui/views/mus/views_mus_test_suite.cc
@@ -252,6 +252,14 @@ void ViewsMusTestSuite::Initialize() {
 
   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>();
 }