Oilpan: move BaseChooserOnlyDateAndTimeInputType to the heap.

third_party/WebKit/Source/core/html/forms/DateInputType.h

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 25 matching lines @@
 
 namespace blink {
 
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
 using BaseDateInputType = BaseMultipleFieldsDateAndTimeInputType;
 #else
 using BaseDateInputType = BaseChooserOnlyDateAndTimeInputType;
 #endif
 
 class DateInputType final : public BaseDateInputType {
+    WILL_BE_USING_DATETIMERCHOOSERCLIENT_GC_MIXIN(DateInputType);

[haraken, 2015/11/22 01:01:39]

Help me understand: Why can't we make BaseChooserOnlyDateAndTimeInputType a GC
mixin instead of making DateInputType a GC mixin? It seems more straightforward
since the DateTimeChooserClient is inherited by
BaseChooserOnlyDateAndTimeInputType.

[sof, 2015/11/22 07:48:55]

Isn't it the rule that the leftmost base should define itself as a GC mixin?

[haraken, 2015/11/22 14:27:09]

I think the rule is as follows.

  class A : public GarbageCollectedMixin { };
  class B : public GarbageCollected<B> { };
  class C : public B, public A { };
  class D : public C { };

We need the USING_GARBAGE_COLLECTED_MIXIN for C but don't need it for D. Am I
wrong?

 public:
     static PassRefPtrWillBeRawPtr<InputType> create(HTMLInputElement&);
+    DEFINE_BASEDATEANDTIMEINPUTTYPE_VIRTUAL_TRACE(BaseDateInputType);
 
 private:
-    DateInputType(HTMLInputElement&);
+    explicit DateInputType(HTMLInputElement&);
+
     void countUsage() override;
     const AtomicString& formControlType() const override;
     StepRange createStepRange(AnyStepHandling) const override;
     bool parseToDateComponentsInternal(const String&, DateComponents*) const override;
     bool setMillisecondToDateComponents(double, DateComponents*) const override;
     void warnIfValueIsInvalid(const String&) const override;
 
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     // BaseMultipleFieldsDateAndTimeInputType functions
     String formatDateTimeFieldsState(const DateTimeFieldsState&) const override;
     void setupLayoutParameters(DateTimeEditElement::LayoutParameters&, const DateComponents&) const override;
     bool isValidFormat(bool hasYear, bool hasMonth, bool hasWeek, bool hasDay, bool hasAMPM, bool hasHour, bool hasMinute, bool hasSecond) const override;
 #endif
 };
 
 } // namespace blink
 
 #endif // DateInputType_h