chromeos: converts DragImageViewTest to AshTestBase

ash/test/ash_test_base.cc

Index: ash/test/ash_test_base.cc
diff --git a/ash/test/ash_test_base.cc b/ash/test/ash_test_base.cc
index ec5972b352b5a1427653f1357fe8f2feeaf072b4..4b2b73cfc196d781bf45b49941da2ba5b6760cfb 100644
--- a/ash/test/ash_test_base.cc
+++ b/ash/test/ash_test_base.cc
@@ -232,6 +232,15 @@ std::unique_ptr<views::Widget> AshTestBase::CreateTestWidget(
   return widget;
 }
 
+std::unique_ptr<aura::Window> AshTestBase::CreateTestWindow(
+    const gfx::Rect& bounds_in_screen,
+    ui::wm::WindowType type,
+    int shell_window_id) {
+  return base::WrapUnique<aura::Window>(
+      CreateTestWindowInShellWithDelegateAndType(nullptr, type, shell_window_id,
+                                                 bounds_in_screen));
+}
+
 aura::Window* AshTestBase::CreateTestWindowInShellWithId(int id) {
   return CreateTestWindowInShellWithDelegate(NULL, id, gfx::Rect());
 }