Allow component IME extension use app.window and add 'ime' window type for app window

ash/shell_unittest.cc

Index: ash/shell_unittest.cc
diff --git a/ash/shell_unittest.cc b/ash/shell_unittest.cc
index aafb8cd8b5280d5f97bdb49ffd1d1858bf8bfe0f..72e5c073bdf393999005065b0656e2d722e93acf 100644
--- a/ash/shell_unittest.cc
+++ b/ash/shell_unittest.cc
@@ -82,7 +82,7 @@ void ExpectAllContainers() {
   EXPECT_TRUE(
       Shell::GetContainer(root_window, kShellWindowId_OverlayContainer));
   EXPECT_TRUE(Shell::GetContainer(
-      root_window, kShellWindowId_VirtualKeyboardParentContainer));
+      root_window, kShellWindowId_ImeWindowParentContainer));
 #if defined(OS_CHROMEOS)
   EXPECT_TRUE(
       Shell::GetContainer(root_window, kShellWindowId_MouseCursorContainer));