Implement cycle window forward/backward by keyboard shortcuts.

ui/aura_shell/test/aura_shell_test_base.cc

Index: ui/aura_shell/test/aura_shell_test_base.cc
diff --git a/ui/aura_shell/test/aura_shell_test_base.cc b/ui/aura_shell/test/aura_shell_test_base.cc
index 3fe7ebd0d672ce70f556ce9f7f1824ba0cd018a4..69a52d6e73e55c52e3244cb25c29747f3bc3c211 100644
--- a/ui/aura_shell/test/aura_shell_test_base.cc
+++ b/ui/aura_shell/test/aura_shell_test_base.cc
@@ -5,6 +5,7 @@
 #include "ui/aura_shell/test/aura_shell_test_base.h"
 
 #include "ui/aura_shell/shell.h"
+#include "ui/aura_shell/test/test_shell_delegate.h"
 
 namespace aura_shell {
 namespace test {
@@ -19,7 +20,7 @@ void AuraShellTestBase::SetUp() {
   aura::test::AuraTestBase::SetUp();
 
   // Creates Shell and hook with Desktop.
-  aura_shell::Shell::CreateInstance(NULL);
+  aura_shell::Shell::CreateInstance(new TestShellDelegate);
 }
 
 void AuraShellTestBase::TearDown() {