Abstract OSMesa from the Layout tests

mash/test/mash_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 "mash/test/mash_test_suite.h"
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/memory/ptr_util.h"
 #include "base/path_service.h"
@@ skipping 45 matching lines @@
 };
 
 MashTestSuite::MashTestSuite(int argc, char** argv) : TestSuite(argc, argv) {}
 
 MashTestSuite::~MashTestSuite() {}
 
 void MashTestSuite::Initialize() {
   base::TestSuite::Initialize();
 
   base::CommandLine::ForCurrentProcess()->AppendSwitch(
-      switches::kOverrideUseGLWithOSMesaForTests);
+      switches::kOverrideUseSoftwareGLForTests);
 
   // Load ash mus strings and resources; not 'common' (Chrome) resources.
   base::FilePath resources;
   PathService::Get(base::DIR_MODULE, &resources);
   resources = resources.Append(FILE_PATH_LITERAL("ash_mus_resources.pak"));
   ui::ResourceBundle::InitSharedInstanceWithPakPath(resources);
 
   base::DiscardableMemoryAllocator::SetInstance(&discardable_memory_allocator_);
   env_ = aura::Env::CreateInstance(aura::Env::Mode::MUS);
 
   compositor_context_factory_ = base::MakeUnique<TestContextFactory>();
   env_->set_context_factory(compositor_context_factory_.get());
 }
 
 void MashTestSuite::Shutdown() {
   env_.reset();
   ui::ResourceBundle::CleanupSharedInstance();
   base::TestSuite::Shutdown();
 }
 
 }  // namespace test
 }  // namespace mash