third_party/WebKit/Source/core/dom/ScopedWindowFocusAllowedIndicator.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef ScopedWindowFocusAllowedIndicator_h
   6 #define ScopedWindowFocusAllowedIndicator_h
   7
   8 #include "core/dom/ContextLifecycleObserver.h"
   9 #include "core/dom/ExecutionContext.h"
  10 #include "wtf/Noncopyable.h"
  11
  12 namespace blink {
  13
  14 class ScopedWindowFocusAllowedIndicator final {
  15     WTF_MAKE_FAST_ALLOCATED(ScopedWindowFocusAllowedIndicator);
  16     WTF_MAKE_NONCOPYABLE(ScopedWindowFocusAllowedIndicator);
  17 public:
  18     explicit ScopedWindowFocusAllowedIndicator(ExecutionContext* executionContext)
  19         : m_observer(adoptPtrWillBeNoop(new Observer(executionContext)))
  20     {
  21     }
  22     ~ScopedWindowFocusAllowedIndicator()
  23     {
  24         m_observer->dispose();
  25     }
  26
  27 private:
  28     class Observer final : public NoBaseWillBeGarbageCollectedFinalized<Observer>, public ContextLifecycleObserver {
  29         WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(Observer);
  30     public:
  31         explicit Observer(ExecutionContext* executionContext)
  32             : ContextLifecycleObserver(executionContext)
  33         {
  34             if (executionContext)
  35                 executionContext->allowWindowInteraction();
  36         }
  37
  38         void dispose()
  39         {
  40             if (executionContext())
  41                 executionContext()->consumeWindowInteraction();
  42         }
  43
  44         DEFINE_INLINE_TRACE()
  45         {
  46             ContextLifecycleObserver::trace(visitor);
  47         }
  48     };
  49
  50     // In Oilpan, destructors are not allowed to touch other on-heap objects.
  51     // The Observer indirection is needed to keep
  52     // ScopedWindowFocusAllowedIndicator off-heap and thus allows its destructor
  53     // to call executionContext()->consumeWindowInteraction().
  54     OwnPtrWillBePersistent<Observer> m_observer;
  55 };
  56
  57 } // namespace blink
  58
  59 #endif // ScopedWindowFocusAllowedIndicator_h