Added common layout framework for system menu rows.

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 0acd4774e148ada381baa6fe5608d614f4c025a7..18dfa68a07db83ad8f0c69fb6ade3297a86508b6 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -356,6 +356,8 @@ component("ash") {
     "common/system/tray/ime_info.h",
     "common/system/tray/label_tray_view.cc",
     "common/system/tray/label_tray_view.h",
+    "common/system/tray/size_range_layout.cc",
+    "common/system/tray/size_range_layout.h",
     "common/system/tray/special_popup_row.cc",
     "common/system/tray/special_popup_row.h",
     "common/system/tray/system_menu_button.cc",
@@ -372,6 +374,8 @@ component("ash") {
     "common/system/tray/system_tray_item.h",
     "common/system/tray/system_tray_notifier.cc",
     "common/system/tray/system_tray_notifier.h",
+    "common/system/tray/three_view_layout.cc",
+    "common/system/tray/three_view_layout.h",
     "common/system/tray/throbber_view.cc",
     "common/system/tray/throbber_view.h",
     "common/system/tray/tray_background_view.cc",
@@ -402,6 +406,8 @@ component("ash") {
     "common/system/tray/tray_popup_label_button.h",
     "common/system/tray/tray_popup_label_button_border.cc",
     "common/system/tray/tray_popup_label_button_border.h",
+    "common/system/tray/tray_popup_layout_factory.cc",
+    "common/system/tray/tray_popup_layout_factory.h",
     "common/system/tray/tray_utils.cc",
     "common/system/tray/tray_utils.h",
     "common/system/tray/view_click_listener.h",
@@ -1223,7 +1229,9 @@ test("ash_unittests") {
     "common/system/chromeos/session/tray_session_length_limit_unittest.cc",
     "common/system/ime/tray_ime_chromeos_unittest.cc",
     "common/system/tiles/tray_tiles_unittest.cc",
+    "common/system/tray/size_range_layout_unittest.cc",
     "common/system/tray/system_tray_unittest.cc",
+    "common/system/tray/three_view_layout_unittest.cc",
     "common/system/tray/tray_details_view_unittest.cc",
     "common/system/user/tray_user_unittest.cc",