chromeos: makes it possible for unittests to honor --mus

This makes it so aura::Env is configured for mus if --mus is specified
on the command line.

BUG=776514
TEST=test only change

Change-Id: Iaeb80b571e274f5bae9af7688d6b55b79e43b3d2
Reviewed-on: https://chromium-review.googlesource.com/823568Reviewed-by: Elliot Glaysher <erg@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523824}

ash/test/ash_test_helper.h

@@ -63,6 +63,9 @@ class AshTestHelper {
   explicit AshTestHelper(AshTestEnvironment* ash_test_environment);
   ~AshTestHelper();
 
+  // This is intended to be called from TestSuites, not individual configs.
+  static void set_config(Config config) { config_ = config; }
+
   // Returns the configuration that tests are run in. See ash::Config enum for
   // details.
   static Config config() { return config_; }

chrome/test/BUILD.gn

@@ -4190,6 +4190,13 @@ static_library("test_support_unit") {
       "//chrome/install_static/test:test_support",
     ]
   }
+
+  if (is_chromeos) {
+    deps = [
+      "//ash:test_support_with_content",
+      "//ash/public/cpp",
+    ]
+  }
 }
 
 if (is_win) {

chrome/test/base/chrome_unit_test_suite.cc

@@ -30,7 +30,11 @@
 #include "ui/gl/test/gl_surface_test_support.h"
 
 #if defined(OS_CHROMEOS)
+#include "ash/public/cpp/config.h"
+#include "ash/test/ash_test_helper.h"
 #include "chromeos/chromeos_paths.h"
+#include "ui/aura/env.h"
+#include "ui/aura/test/aura_test_context_factory.h"
 #endif
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
@@ -107,6 +111,16 @@ void ChromeUnitTestSuite::Initialize() {
 
   base::DiscardableMemoryAllocator::SetInstance(&discardable_memory_allocator_);
   ProfileShortcutManager::DisableForUnitTests();
+
+#if defined(OS_CHROMEOS)
+  aura::Env* env = aura::Env::GetInstance();
+  if (env->mode() == aura::Env::Mode::MUS) {
+    ash::AshTestHelper::set_config(ash::Config::MUS);
+    context_factory_ = std::make_unique<aura::test::AuraTestContextFactory>();
+    env->set_context_factory(context_factory_.get());
+    env->set_context_factory_private(nullptr);
+  }
+#endif
 }
 
 void ChromeUnitTestSuite::Shutdown() {

chrome/test/base/chrome_unit_test_suite.h

@@ -5,12 +5,20 @@
 #ifndef CHROME_TEST_BASE_CHROME_UNIT_TEST_SUITE_H_
 #define CHROME_TEST_BASE_CHROME_UNIT_TEST_SUITE_H_
 
+#include <memory>
+
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/test/test_discardable_memory_allocator.h"
 #include "chrome/test/base/chrome_test_suite.h"
 
+#if defined(OS_CHROMEOS)
+namespace ui {
+class ContextFactory;
+}
+#endif
+
 // Test suite for unit tests. Creates additional stub services that are not
 // needed for browser tests (e.g. a TestingBrowserProcess).
 class ChromeUnitTestSuite : public ChromeTestSuite {
@@ -31,6 +39,12 @@ class ChromeUnitTestSuite : public ChromeTestSuite {
  private:
   base::TestDiscardableMemoryAllocator discardable_memory_allocator_;
 
+#if defined(OS_CHROMEOS)
+  // Only used when running in mus/mash, and is set as the context_factory
+  // on aura::Env.
+  std::unique_ptr<ui::ContextFactory> context_factory_;
+#endif
+
   DISALLOW_COPY_AND_ASSIGN(ChromeUnitTestSuite);
 };