[Oilpan] Move ScrollAnimators onto oilpan heap

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
index 85016be74b5a15c2f326a65e4254a439ceac12f6..2874d85de5f967f256fdfd2ef992d63bd4539f6b 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp
@@ -54,7 +54,7 @@ struct SameSizeAsScrollableArea {
 #if ENABLE(ASSERT) && ENABLE(OILPAN)
     VerifyEagerFinalization verifyEager;
 #endif
-    void* pointer;
+    OwnPtrWillBeMember<void*> pointer[2];
     unsigned bitfields : 16;
     IntPoint origin;
 };
@@ -93,29 +93,28 @@ ScrollableArea::~ScrollableArea()
 
 void ScrollableArea::clearScrollAnimators()
 {
-    m_animators.clear();
+#if OS(MACOSX) && ENABLE(OILPAN)

[peria, 2015/12/03 13:42:08]

This clearing is added to make the probability to kick the timer in
ScrollAnimatorMac small.

[haraken, 2015/12/03 14:48:47]

Add something to make the likelihood small sounds bad, since it means that we
have a bug...

In oilpan, why do we need to explicitly call cleanup() here? Given the following
facts, it should not happen that the ScrollAnimator's timer is invoked after the
ScrollableArea dies.

- Both ScrollAnimator and ScrollableArea are on oilpan's heap.
- The ScrollAnimator has a strong reference to the ScrollableArea. Thus it
should not happen that the ScrollableArea dies before the ScrollAnimator.
- If the ScrollableArea and the ScrollAnimator die in the same GC cycle (this
can happen), the ScrollAnimator's pre-finalizer runs cleanup() and stops the
timer. Thus the timer should not be triggered after the ScrollableArea gets
destructed.

In conclusion, I think that we don't need to call cleanup() here. Am I missing
something?

+    if (m_scrollAnimator)
+        m_scrollAnimator->cleanup();
+#endif
+    m_scrollAnimator.clear();
+    m_programmaticScrollAnimator.clear();
 }
 
 ScrollAnimatorBase* ScrollableArea::scrollAnimator() const
 {
-    if (!m_animators)
-        m_animators = adoptPtr(new ScrollableAreaAnimators);
-
-    if (!m_animators->scrollAnimator)
-        m_animators->scrollAnimator = ScrollAnimatorBase::create(const_cast<ScrollableArea*>(this));
+    if (!m_scrollAnimator)
+        m_scrollAnimator = ScrollAnimatorBase::create(const_cast<ScrollableArea*>(this));
 
-    return m_animators->scrollAnimator.get();
+    return m_scrollAnimator.get();
 }
 
 ProgrammaticScrollAnimator* ScrollableArea::programmaticScrollAnimator() const
 {
-    if (!m_animators)
-        m_animators = adoptPtr(new ScrollableAreaAnimators);
-
-    if (!m_animators->programmaticScrollAnimator)
-        m_animators->programmaticScrollAnimator = ProgrammaticScrollAnimator::create(const_cast<ScrollableArea*>(this));
+    if (!m_programmaticScrollAnimator)
+        m_programmaticScrollAnimator = ProgrammaticScrollAnimator::create(const_cast<ScrollableArea*>(this));
 
-    return m_animators->programmaticScrollAnimator.get();
+    return m_programmaticScrollAnimator.get();
 }
 
 void ScrollableArea::setScrollOrigin(const IntPoint& origin)
@@ -584,4 +583,10 @@ IntSize ScrollableArea::excludeScrollbars(const IntSize& size) const
 
 }
 
+DEFINE_TRACE(ScrollableArea)
+{
+    visitor->trace(m_scrollAnimator);
+    visitor->trace(m_programmaticScrollAnimator);
+}
+
 } // namespace blink