Consolidate bubble border code.

ash/wm/app_list_controller.cc

Index: ash/wm/app_list_controller.cc
diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index 8f6ebcb9a9963d4b8c1ca7e83baa4788535cbded..6cbb20bbf7453d167d3f640679052ee6fcfe6973 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -49,14 +49,14 @@ views::BubbleBorder::ArrowLocation GetBubbleArrowLocation() {
   ShelfAlignment shelf_alignment = Shell::GetInstance()->GetShelfAlignment();
   switch (shelf_alignment) {
     case ash::SHELF_ALIGNMENT_BOTTOM:
-      return views::BubbleBorder::BOTTOM_RIGHT;
+      return views::BubbleBorder::BOTTOM_CENTER;
     case ash::SHELF_ALIGNMENT_LEFT:
-      return views::BubbleBorder::LEFT_BOTTOM;
+      return views::BubbleBorder::LEFT_CENTER;
     case ash::SHELF_ALIGNMENT_RIGHT:
-      return views::BubbleBorder::RIGHT_BOTTOM;
+      return views::BubbleBorder::RIGHT_CENTER;
     default:
       NOTREACHED() << "Unknown shelf alignment " << shelf_alignment;
-      return views::BubbleBorder::BOTTOM_RIGHT;
+      return views::BubbleBorder::BOTTOM_CENTER;
   }
 }