Use a mocked compositor for unit tests

ui/aura/test/aura_test_base.cc

Index: ui/aura/test/aura_test_base.cc
diff --git a/ui/aura/test/aura_test_base.cc b/ui/aura/test/aura_test_base.cc
index 1e4eb41e5f2148fcb03690933c7148c506a16ebe..e132ebdf0baf70b769ee6fe5a65b9e2e4acf5b50 100644
--- a/ui/aura/test/aura_test_base.cc
+++ b/ui/aura/test/aura_test_base.cc
@@ -10,15 +10,10 @@
 
 #include "ui/aura/desktop.h"
 #include "ui/aura/test/test_desktop_delegate.h"
-#include "ui/gfx/compositor/test_compositor.h"
 
 namespace aura {
 namespace test {
 
-static ui::Compositor* TestCreateCompositor() {
-  return new ui::TestCompositor();
-}
-
 AuraTestBase::AuraTestBase()
     : setup_called_(false),
       teardown_called_(false) {
@@ -40,7 +35,6 @@ AuraTestBase::~AuraTestBase() {
 void AuraTestBase::SetUp() {
   testing::Test::SetUp();
   setup_called_ = true;
-  aura::Desktop::set_compositor_factory_for_testing(&TestCreateCompositor);
   // TestDesktopDelegate is owned by the desktop.
   new TestDesktopDelegate();
   Desktop::GetInstance()->Show();
@@ -53,7 +47,6 @@ void AuraTestBase::TearDown() {
   RunPendingMessages();
   teardown_called_ = true;
   testing::Test::TearDown();
-  aura::Desktop::set_compositor_factory_for_testing(NULL);
 }
 
 }  // namespace test