Adding split view divider widget.

athena/athena.gyp

Index: athena/athena.gyp
diff --git a/athena/athena.gyp b/athena/athena.gyp
index 7a6c3bea4c52a6e63b8683e0493d6b983c903b2e..305d2f897361eee3d909d54830fdcb0fdaeddcfa 100644
--- a/athena/athena.gyp
+++ b/athena/athena.gyp
@@ -51,11 +51,6 @@
         'activity/public/activity_view_manager.h',
         'activity/public/activity_view_model.h',
         'athena_export.h',
-        'util/container_priorities.h',
-        'util/fill_layout_manager.cc',
-        'util/fill_layout_manager.h',
-        'util/switches.cc',
-        'util/switches.h',
         'env/athena_env_impl.cc',
         'env/public/athena_env.h',
         'home/app_list_view_delegate.cc',
@@ -102,6 +97,13 @@
         'system/time_view.h',
         'system/public/system_ui.h',
         'system/system_ui_impl.cc',
+        'util/container_priorities.h',
+        'util/drag_handle.cc',
+        'util/drag_handle.h',
+        'util/fill_layout_manager.cc',
+        'util/fill_layout_manager.h',
+        'util/switches.cc',
+        'util/switches.h',
         'wm/bezel_controller.cc',
         'wm/bezel_controller.h',
         'wm/overview_toolbar.cc',
@@ -250,7 +252,6 @@
       ],
       'sources': [
         'activity/activity_manager_unittest.cc',
-        'util/fill_layout_manager_unittest.cc',
         'content/app_activity_unittest.cc',
         'env/athena_env_unittest.cc',
         'home/athena_start_page_view_unittest.cc',
@@ -261,6 +262,8 @@
         'resource_manager/resource_manager_unittest.cc',
         'screen/screen_manager_unittest.cc',
         'test/athena_unittests.cc',
+        'util/drag_handle_unittest.cc',
+        'util/fill_layout_manager_unittest.cc',
         'wm/split_view_controller_unittest.cc',
         'wm/window_list_provider_impl_unittest.cc',
         'wm/window_manager_unittest.cc',