ui: No more TestCompositor. Use NullDraw contexts in unit tests.

ash/test/ash_test_helper.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 "ash/test/ash_test_helper.h"
 
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/ash_switches.h"
 #include "ash/shell.h"
 #include "ash/test/display_manager_test_api.h"
@@ skipping 40 matching lines @@
 }
 
 void AshTestHelper::SetUp(bool start_session) {
   wm_state_.reset(new views::corewm::WMState);
 
   // Disable animations during tests.
   zero_duration_mode_.reset(new ui::ScopedAnimationDurationScaleMode(
       ui::ScopedAnimationDurationScaleMode::ZERO_DURATION));
   ui::InitializeInputMethodForTesting();
 
-  bool allow_test_contexts = true;
-  ui::InitializeContextFactoryForTests(allow_test_contexts);
+  bool enable_pixel_output = false;
+  ui::InitializeContextFactoryForTests(enable_pixel_output);
 
   // Creates Shell and hook with Desktop.
   test_shell_delegate_ = new TestShellDelegate;
 
   // Creates MessageCenter since g_browser_process is not created in AshTestBase
   // tests.
   message_center::MessageCenter::Initialize();
 
 #if defined(OS_CHROMEOS)
   // Create DBusThreadManager for testing.
@@ skipping 66 matching lines @@
 aura::Window* AshTestHelper::CurrentContext() {
   aura::Window* root_window = Shell::GetTargetRootWindow();
   if (!root_window)
     root_window = Shell::GetPrimaryRootWindow();
   DCHECK(root_window);
   return root_window;
 }
 
 }  // namespace test
 }  // namespace ash