Improve doc of ViewObserver and clarify arguments

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/ash_export.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
@@ skipping 49 matching lines @@
                              const gfx::Rect& new_bounds) override;
 
   // views::WidgetRemovalsObserver
   void OnWillRemoveView(views::Widget* widget, views::View* view) override;
 
   // views::WidgetObserver
   void OnWidgetBoundsChanged(views::Widget* widget,
                              const gfx::Rect& new_bounds) override;
 
   // views::ViewObserver
-  void OnChildViewRemoved(views::View* view, views::View* parent) override;
-  void OnChildViewAdded(views::View* view) override;
-  void OnChildViewReordered(views::View*) override;
+  void OnChildViewRemoved(views::View* parent, views::View* view) override;
+  void OnChildViewAdded(views::View* parent, views::View* view) override;
+  void OnChildViewReordered(views::View* parent, views::View*) override;
   void OnViewBoundsChanged(views::View* view) override;
 
   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);
 
@@ skipping 65 matching lines @@
 
   base::ObserverList<AshDevToolsDOMAgentObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(AshDevToolsDOMAgent);
 };
 
 }  // namespace devtools
 }  // namespace ash
 
 #endif  // ASH_COMMON_DEVTOOLS_ASH_DEVTOOLS_DOM_AGENT_H_