Improve doc of ViewObserver and clarify arguments

ui/views/view_unittest.cc

 // Copyright (c) 2012 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.
 
 #include "ui/views/view.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
@@ skipping 4849 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // Observer tests.
 ////////////////////////////////////////////////////////////////////////////////
 
 class ViewObserverTest : public ViewTest, public ViewObserver {
  public:
   ViewObserverTest()
       : child_view_added_times_(0),
         child_view_removed_times_(0),
+        child_view_added_parent_(nullptr),
         child_view_added_(nullptr),
         child_view_removed_(nullptr),
         child_view_removed_parent_(nullptr),
         view_visibility_changed_(nullptr),
         view_enabled_changed_(nullptr),
         view_bounds_changed_(nullptr),
         view_reordered_(nullptr) {}
 
   ~ViewObserverTest() override {}
 
   // ViewObserver:
-  void OnChildViewAdded(View* child) override {
+  void OnChildViewAdded(View* parent, View* child) override {
     child_view_added_times_++;
     child_view_added_ = child;
+    child_view_added_parent_ = parent;
   }
-  void OnChildViewRemoved(View* child, View* parent) override {
+  void OnChildViewRemoved(View* parent, View* child) override {
     child_view_removed_times_++;
     child_view_removed_ = child;
     child_view_removed_parent_ = parent;
   }
 
   void OnViewVisibilityChanged(View* view) override {
     view_visibility_changed_ = view;
   }
 
   void OnViewEnabledChanged(View* view) override {
     view_enabled_changed_ = view;
   }
 
   void OnViewBoundsChanged(View* view) override { view_bounds_changed_ = view; }
 
-  void OnChildViewReordered(View* view) override { view_reordered_ = view; }
+  void OnChildViewReordered(View* parent, View* view) override {
+    view_reordered_ = view;
+  }
 
   void reset() {
     child_view_added_times_ = 0;
     child_view_removed_times_ = 0;
     child_view_added_ = nullptr;
+    child_view_added_parent_ = nullptr;
     child_view_removed_ = nullptr;
     child_view_removed_parent_ = nullptr;
     view_visibility_changed_ = nullptr;
     view_enabled_changed_ = nullptr;
     view_bounds_changed_ = nullptr;
     view_reordered_ = nullptr;
   }
 
   std::unique_ptr<View> NewView() {
     auto view = base::MakeUnique<View>();
     view->AddObserver(this);
     return view;
   }
 
   int child_view_added_times() { return child_view_added_times_; }
   int child_view_removed_times() { return child_view_removed_times_; }
   const View* child_view_added() const { return child_view_added_; }
+  const View* child_view_added_parent() const {
+    return child_view_added_parent_;
+  }
   const View* child_view_removed() const { return child_view_removed_; }
   const View* child_view_removed_parent() const {
     return child_view_removed_parent_;
   }
   const View* view_visibility_changed() const {
     return view_visibility_changed_;
   }
   const View* view_enabled_changed() const { return view_enabled_changed_; }
   const View* view_bounds_changed() const { return view_bounds_changed_; }
   const View* view_reordered() const { return view_reordered_; }
 
  private:
   int child_view_added_times_;
   int child_view_removed_times_;
 
+  View* child_view_added_parent_;
   View* child_view_added_;
   View* child_view_removed_;
   View* child_view_removed_parent_;
   View* view_visibility_changed_;
   View* view_enabled_changed_;
   View* view_bounds_changed_;
   View* view_reordered_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewObserverTest);
 };
 
 TEST_F(ViewObserverTest, ViewParentChanged) {
   std::unique_ptr<View> parent1 = NewView();
   std::unique_ptr<View> parent2 = NewView();
   std::unique_ptr<View> child_view = NewView();
 
   parent1->AddChildView(child_view.get());
   EXPECT_EQ(0, child_view_removed_times());
   EXPECT_EQ(1, child_view_added_times());
   EXPECT_EQ(child_view.get(), child_view_added());
-  EXPECT_EQ(child_view.get()->parent(), parent1.get());
+  EXPECT_EQ(child_view->parent(), child_view_added_parent());
+  EXPECT_EQ(child_view->parent(), parent1.get());
   reset();
 
   // Removed from parent1, added to parent2
   parent2->AddChildView(child_view.get());
   EXPECT_EQ(1, child_view_removed_times());
   EXPECT_EQ(1, child_view_added_times());
   EXPECT_EQ(child_view.get(), child_view_removed());
   EXPECT_EQ(parent1.get(), child_view_removed_parent());
   EXPECT_EQ(child_view.get(), child_view_added());
-  EXPECT_EQ(child_view.get()->parent(), parent2.get());
+  EXPECT_EQ(child_view->parent(), parent2.get());
 
   reset();
 
   parent2->RemoveChildView(child_view.get());
   EXPECT_EQ(1, child_view_removed_times());
   EXPECT_EQ(0, child_view_added_times());
   EXPECT_EQ(child_view.get(), child_view_removed());
   EXPECT_EQ(parent2.get(), child_view_removed_parent());
 }
 
@@ skipping 30 matching lines @@
   std::unique_ptr<View> view = NewView();
   std::unique_ptr<View> child_view = NewView();
   std::unique_ptr<View> child_view2 = NewView();
   view->AddChildView(child_view.get());
   view->AddChildView(child_view2.get());
   view->ReorderChildView(child_view2.get(), 0);
   EXPECT_EQ(child_view2.get(), view_reordered());
 }
 
 }  // namespace views