Don't shrink the message center height while open

ui/message_center/views/message_list_view.h

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_MESSAGE_CENTER_VIEWS_MESSAGE_LIST_VIEW_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_LIST_VIEW_H_
 
 #include <list>
 #include <set>
 #include <vector>
 
 #include "base/macros.h"
 #include "ui/compositor/paint_context.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
 #include "ui/message_center/message_center_export.h"
 #include "ui/message_center/notification.h"
 #include "ui/views/animation/bounds_animator.h"
 #include "ui/views/animation/bounds_animator_observer.h"
+#include "ui/views/controls/scroll_view.h"
 #include "ui/views/view.h"
 
 namespace ui {
 class Layer;
 }
 
 namespace message_center {
 
 class MessageView;
 
@@ skipping 18 matching lines @@
   void SetRepositionTarget(const gfx::Rect& target_rect);
   void ResetRepositionSession();
   void ClearAllClosableNotifications(const gfx::Rect& visible_scroll_rect);
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   void SetRepositionTargetForTest(
       const gfx::Rect& target_rect);
 
+  void set_scroller(views::ScrollView* scroller) { scroller_ = scroller; }
+
  protected:
   // Overridden from views::View.
   void Layout() override;
   gfx::Size GetPreferredSize() const override;
   int GetHeightForWidth(int width) const override;
   void PaintChildren(const ui::PaintContext& context) override;
   void ReorderChildLayers(ui::Layer* parent_layer) override;
 
   // Overridden from views::BoundsAnimatorObserver.
   void OnBoundsAnimatorProgressed(views::BoundsAnimator* animator) override;
   void OnBoundsAnimatorDone(views::BoundsAnimator* animator) override;
 
  private:
   friend class MessageCenterViewTest;
   friend class MessageListViewTest;
 
   bool IsValidChild(const views::View* child) const;
   void DoUpdateIfPossible();
 
   // Animates all notifications below target upwards to align with the top of
   // the last closed notification.
   void AnimateNotificationsBelowTarget();
-  // Animates all notifications above target downwards to align with the top of
-  // the last closed notification.
-  void AnimateNotificationsAboveTarget();
+  // Animates all notifications to align with the top of the last closed
+  // notification.
+  void AnimateNotifications();
   // Computes reposition offsets for |AnimateNotificationsAboveTarget|.
   std::vector<int> ComputeRepositionOffsets(const std::vector<int>& heights,
                                             const std::vector<bool>& deleting,
                                             int target_index,
                                             int padding);
 
   // Schedules animation for a child to the specified position. Returns false
   // if |child| will disappear after the animation.
   bool AnimateChild(views::View* child,
                     int top,
                     int height,
                     bool animate_even_on_move);
 
+  // Calculate the new fixed height and update with it. |requested_height|
+  // is the minimum height, and actual fixed height should be more than it.
+  void UpdateFixedHeight(int requested_height, bool prevent_scroll);
+
   // Animate clearing one notification.
   void AnimateClearingOneNotification();
 
   // List of MessageListView::Observer
   base::ObserverList<Observer> observers_;
 
   // The top position of the reposition target rectangle.
   int reposition_top_;
   int fixed_height_;
   bool has_deferred_task_;
   bool clear_all_started_;
   std::set<views::View*> adding_views_;
   std::set<views::View*> deleting_views_;
   std::set<views::View*> deleted_when_done_;
   std::list<views::View*> clearing_all_views_;
   views::BoundsAnimator animator_;
 
+  views::ScrollView* scroller_ = nullptr;
+
   // If true, the message loop will be quitted after the animation finishes.
   // This is just for tests and has no setter.
   bool quit_message_loop_after_animation_for_test_;
 
   base::WeakPtrFactory<MessageListView> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(MessageListView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_LIST_VIEW_H_