Implement message center on Windows

ui/views/bubble/tray_bubble_view.h

Index: ui/views/bubble/tray_bubble_view.h
diff --git a/ui/views/bubble/tray_bubble_view.h b/ui/views/bubble/tray_bubble_view.h
index 2a2ea443bb610594bbf6020cf4d72d90b411c66a..a01930e9904ce1c50a992dc36fe302b0f2c19434 100644
--- a/ui/views/bubble/tray_bubble_view.h
+++ b/ui/views/bubble/tray_bubble_view.h
@@ -34,7 +34,7 @@ class VIEWS_EXPORT TrayBubbleView : public views::BubbleDelegateView {
  public:
   enum AnchorType {
     ANCHOR_TYPE_TRAY,
-    ANCHOR_TYPE_BUBBLE
+    ANCHOR_TYPE_BUBBLE,
   };
 
   enum AnchorAlignment {
@@ -86,6 +86,9 @@ class VIEWS_EXPORT TrayBubbleView : public views::BubbleDelegateView {
                int max_width);
     AnchorType anchor_type;
     AnchorAlignment anchor_alignment;
+    // The anchor_point is used when no anchor view is available.
+    int anchor_point_x;
+    int anchor_point_y;
     int min_width;
     int max_width;
     int max_height;
@@ -95,6 +98,7 @@ class VIEWS_EXPORT TrayBubbleView : public views::BubbleDelegateView {
     views::BubbleBorder::ArrowLocation arrow_location;
     int arrow_offset;
     views::BubbleBorder::Shadow shadow;
+    views::BubbleBorder::BubbleAlignment arrow_alignment;
   };
 
   // Constructs and returns a TrayBubbleView. init_params may be modified.