Oilpan: disable conservative GCs during initial GC mixin construction.

Source/core/frame/DeviceSingleWindowEventController.h

Index: Source/core/frame/DeviceSingleWindowEventController.h
diff --git a/Source/core/frame/DeviceSingleWindowEventController.h b/Source/core/frame/DeviceSingleWindowEventController.h
index 5f08fe76c443aa8f4a807406710a922c8c3e6603..1d712f0522469320390b0ed099bfb077c6f33f3a 100644
--- a/Source/core/frame/DeviceSingleWindowEventController.h
+++ b/Source/core/frame/DeviceSingleWindowEventController.h
@@ -15,7 +15,6 @@ class Document;
 class Event;
 
 class DeviceSingleWindowEventController : public NoBaseWillBeGarbageCollectedFinalized<DeviceSingleWindowEventController>, public PlatformEventController, public DOMWindowLifecycleObserver {
-    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(DeviceSingleWindowEventController);

[haraken, 2015/03/05 02:20:19]

Why can we remove this?

[sof, 2015/03/05 07:14:58]

It's an abstract class with all objects that implement it are also declared as
GC mixins. The declaration here serves no purpose?

(I can split the change out, its presence initially created some extra problems
for this CL.)

 public:
     virtual ~DeviceSingleWindowEventController();
 
@@ -29,10 +28,10 @@ public:
     virtual void didRemoveAllEventListeners(LocalDOMWindow*) override;
 
 protected:
-    Document& document() const { return *m_document; }
-
     explicit DeviceSingleWindowEventController(Document&);
 
+    Document& document() const { return *m_document; }
+
     void dispatchDeviceEvent(const PassRefPtrWillBeRawPtr<Event>);
 
     virtual PassRefPtrWillBeRawPtr<Event> lastEvent() const = 0;