Fixes a crash when InkDropDelegate gets destroyed after its InkDropHost

ui/views/animation/ink_drop_delegate_unittest.cc

+// Copyright 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.
+
+#include "ui/views/animation/ink_drop_delegate.h"
+
+#include "ui/views/animation/ink_drop_host.h"
+#include "ui/views/controls/button/custom_button.h"
+#include "ui/views/test/views_test_base.h"
+
+namespace views {
+
+namespace {
+
+// An InkDropDelegate that keeps track of order of deletions.
+class TestInkDropDelegate : public InkDropDelegate {
+ public:
+  TestInkDropDelegate(InkDropHost* ink_drop_host,
+                      bool* button_deleted,
+                      bool* delegate_deleted)
+      : ink_drop_host_(ink_drop_host),
+        button_deleted_(button_deleted),
+        delegate_deleted_(delegate_deleted) {
+    ink_drop_host_->AddInkDropLayer(nullptr);
+  }
+  ~TestInkDropDelegate() override {
+    EXPECT_FALSE(*button_deleted_);
+    ink_drop_host_->RemoveInkDropLayer(nullptr);
+    *delegate_deleted_ = true;
+  }
+
+  // InkDropDelegate:
+  void SetInkDropSize(int large_size,
+                      int large_corner_radius,
+                      int small_size,
+                      int small_corner_radius) override {}
+  void OnLayout() override {}
+  void OnAction(InkDropState state) override {}
+
+ private:
+  InkDropHost* ink_drop_host_;
+  bool* button_deleted_;
+  bool* delegate_deleted_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestInkDropDelegate);
+};
+
+// A test Button class that owns a TestInkDropDelegate.
+class TestButton : public views::CustomButton, public views::InkDropHost {
+ public:
+  TestButton(bool* layer_added,
+             bool* layer_removed,
+             bool* button_deleted,
+             bool* delegate_deleted)
+      : CustomButton(nullptr),
+        layer_added_(layer_added),
+        layer_removed_(layer_removed),
+        button_deleted_(button_deleted) {
+    scoped_ptr<views::InkDropDelegate> new_ink_drop_delegate(
+        new TestInkDropDelegate(this, button_deleted, delegate_deleted));
+    SetInkDropDelegate(new_ink_drop_delegate.Pass());
+    EXPECT_TRUE(*layer_added_);
+  }
+  ~TestButton() override {
+    SetInkDropDelegate(scoped_ptr<views::InkDropDelegate>());
+    EXPECT_TRUE(*layer_removed_);
+    *button_deleted_ = true;
+  }
+
+  // views::InkDropHost:
+  void AddInkDropLayer(ui::Layer* ink_drop_layer) override {
+    *layer_added_ = true;
+  }
+  void RemoveInkDropLayer(ui::Layer* ink_drop_layer) override {
+    *layer_removed_ = true;
+  }
+  gfx::Point CalculateInkDropCenter() const override { return gfx::Point(); }
+
+ private:
+  bool* layer_added_;
+  bool* layer_removed_;
+  bool* button_deleted_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestButton);
+};
+
+}  // namespace
+
+// Test that an InkDropDelegate gets safely deleted when a CustomButton is
+// destroyed.
+TEST(InkDropDelegateTest, CanBeDeleted) {
+  bool layer_added = false;
+  bool layer_removed = false;
+  bool button_deleted = false;
+  bool delegate_deleted = false;
+
+  TestButton* button = new TestButton(&layer_added, &layer_removed,
+                                      &button_deleted, &delegate_deleted);
+  EXPECT_TRUE(layer_added);
+  EXPECT_FALSE(layer_removed);
+  EXPECT_FALSE(button_deleted);
+  EXPECT_FALSE(delegate_deleted);
+
+  delete button;
+  EXPECT_TRUE(layer_added);
+  EXPECT_TRUE(layer_removed);
+  EXPECT_TRUE(button_deleted);
+  EXPECT_TRUE(delegate_deleted);
+}
+
+}  // namespace views