components/user_education/common/help_bubble.cc

// Copyright 2021 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 "components/user_education/common/help_bubble.h"

#include "base/auto_reset.h"
#include "base/notreached.h"

namespace user_education {

HelpBubble::HelpBubble()
    : on_close_callbacks_(std::make_unique<CallbackList>()) {}

HelpBubble::~HelpBubble() {
  // Derived classes must call Close() in destructor lest the bubble be
  // destroyed without cleaning up the framework-specific implementation. Since
  // Close() itself depends on framework-specific logic, however, it cannot be
  // called here, as virtual functions are no longer available in the base
  // destructor.
  CHECK(is_closed());
}

bool HelpBubble::Close() {
  // This prevents us from re-entrancy during CloseBubbleImpl() or after the
  // bubble is closed.
  if (is_closed() || closing_)
    return false;

  {
    // Prevent re-entrancy until is_closed() becomes true, which happens during
    // NotifyBubbleClosed().
    base::AutoReset<bool> closing_guard(&closing_, true);
    CloseBubbleImpl();
  }

  // This call could delete `this` so no code can come after it.
  NotifyBubbleClosed();
  return true;
}

void HelpBubble::OnAnchorBoundsChanged() {}

gfx::Rect HelpBubble::GetBoundsInScreen() const {
  return gfx::Rect();
}

base::CallbackListSubscription HelpBubble::AddOnCloseCallback(
    ClosedCallback callback) {
  if (is_closed()) {
    NOTREACHED();
    return base::CallbackListSubscription();
  }

  return on_close_callbacks_->Add(std::move(callback));
}

void HelpBubble::NotifyBubbleClosed() {
  // We can't destruct the callback list during callbacks, so ensure that it
  // sticks around until the callbacks are all finished. This also has the side
  // effect of making is_closed() true since it resets the value of
  // `on_close_callbacks_`.
  std::unique_ptr<CallbackList> temp = std::move(on_close_callbacks_);
  if (temp)
    temp->Notify(this);
}

}  // namespace user_education