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 166ae62d2fb8be67765e37c8ec6e2b7847ea280a..60943f469c733708b05202b1355029c5767aff94 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -357,6 +357,8 @@ 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",
@@ -373,6 +375,8 @@ 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",
@@ -403,6 +407,8 @@ 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",