Move PlatformEventDispatcher implementations to the Oilpan heap.

Source/modules/screen_orientation/ScreenOrientationDispatcher.cpp

 // Copyright 2014 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 "config.h"
 #include "modules/screen_orientation/ScreenOrientationDispatcher.h"
 
 #include "public/platform/Platform.h"
 
 namespace blink {
 
 ScreenOrientationDispatcher& ScreenOrientationDispatcher::instance()
 {
-    DEFINE_STATIC_LOCAL(ScreenOrientationDispatcher, screenOrientationDispatcher, ());
-    return screenOrientationDispatcher;
+    DEFINE_STATIC_LOCAL(Persistent<ScreenOrientationDispatcher>, screenOrientationDispatcher, (new ScreenOrientationDispatcher()));
+    return *screenOrientationDispatcher;
 }
 
 ScreenOrientationDispatcher::ScreenOrientationDispatcher()
 {
 }
 
-ScreenOrientationDispatcher::~ScreenOrientationDispatcher()
+void ScreenOrientationDispatcher::trace(Visitor* visitor)
 {
+    PlatformEventDispatcher::trace(visitor);
 }
 
 void ScreenOrientationDispatcher::startListening()
 {
     Platform::current()->startListening(WebPlatformEventScreenOrientation, 0);
 }
 
 void ScreenOrientationDispatcher::stopListening()
 {
     Platform::current()->stopListening(WebPlatformEventScreenOrientation);
 }
 
 } // namespace blink