Refactor remove methods, add DCHECKS, and remove_observer boolean

ash/common/devtools/ash_devtools_dom_agent.h

 // Copyright 2016 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 ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_DOM_AGENT_H_
 #define ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_DOM_AGENT_H_
 
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window_observer.h"
 #include "base/compiler_specific.h"
@@ skipping 27 matching lines @@
 
   WmWindow* GetWindowFromNodeId(int nodeId);
   views::Widget* GetWidgetFromNodeId(int nodeId);
   views::View* GetViewFromNodeId(int nodeId);
 
   int GetNodeIdFromWindow(WmWindow* window);
   int GetNodeIdFromWidget(views::Widget* widget);
   int GetNodeIdFromView(views::View* view);
 
  private:
+  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildInitialTree();
+  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildTreeForWindow(
+      WmWindow* window);
+  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildTreeForRootWidget(
+      views::Widget* widget);
   std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildTreeForView(
       views::View* view);
-  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildTreeForRootWidget(
-      views::Widget* widget);
-  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildTreeForWindow(
-      WmWindow* window);
-  std::unique_ptr<ui::devtools::protocol::DOM::Node> BuildInitialTree();
-  void AddWindowNode(WmWindow* window);
-  void RemoveWindowNode(WmWindow* window);
-  void RemoveWidgetNode(views::Widget* widget);
-  void RemoveViewNode(views::View* view);
+
+  void AddWindowTree(WmWindow* window);
+  // |remove_observer| ensures that we don't add a duplicate observer in any
+  // observer callback. For example, |remove_observer| is false when rebuilding
+  // the tree in OnWindowStackingChanged so that the observer is not removed and
+  // re-added, thus causing endless calls on the observer.
+  void RemoveWindowTree(WmWindow* window, bool remove_observer);
+  void RemoveWindowNode(WmWindow* window, bool remove_observer);
+
+  void RemoveWidgetTree(views::Widget* widget, bool remove_observer);
+  void RemoveWidgetNode(views::Widget* widget, bool remove_observer);
+
+  void RemoveViewTree(views::View* view,
+                      views::View* parent,
+                      bool remove_observer);
+  void RemoveViewNode(views::View* view,
+                      views::View* parent,
+                      bool remove_observer);
+
   void RemoveObserverFromAllWindows();
-  void AddRootWindowObservers();
   void Reset();
 
   ash::WmShell* shell_;
 
   using WindowToNodeIdMap = std::unordered_map<WmWindow*, int>;
   WindowToNodeIdMap window_to_node_id_map_;
   using NodeIdToWindowMap = std::unordered_map<int, WmWindow*>;
   NodeIdToWindowMap node_id_to_window_map_;
 
   using WidgetToNodeIdMap = std::unordered_map<views::Widget*, int>;
   WidgetToNodeIdMap widget_to_node_id_map_;
   using NodeIdToWidgetMap = std::unordered_map<int, views::Widget*>;
   NodeIdToWidgetMap node_id_to_widget_map_;
 
   using ViewToNodeIdMap = std::unordered_map<views::View*, int>;
   ViewToNodeIdMap view_to_node_id_map_;
   using NodeIdToViewMap = std::unordered_map<int, views::View*>;
   NodeIdToViewMap node_id_to_view_map_;
 
   DISALLOW_COPY_AND_ASSIGN(AshDevToolsDOMAgent);
 };
 
 }  // namespace devtools
 }  // namespace ash
 
 #endif  // ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_DOM_AGENT_H_