Move ScrollbarManager from core to platform and use as Scrollbar parent

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

Index: third_party/WebKit/Source/platform/scroll/ScrollbarManager.cpp
diff --git a/third_party/WebKit/Source/core/paint/ScrollbarManager.cpp b/third_party/WebKit/Source/platform/scroll/ScrollbarManager.cpp
similarity index 58%
rename from third_party/WebKit/Source/core/paint/ScrollbarManager.cpp
rename to third_party/WebKit/Source/platform/scroll/ScrollbarManager.cpp
index 4b270c2fdc07abcc787922c4bb576e195c49fb24..43c4894a61b9e4fe29555a8a885e58f8bc49cf51 100644
--- a/third_party/WebKit/Source/core/paint/ScrollbarManager.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollbarManager.cpp
@@ -2,23 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "core/paint/ScrollbarManager.h"
+#include "platform/scroll/ScrollbarManager.h"
 
 namespace blink {
 
-ScrollbarManager::ScrollbarManager(ScrollableArea& scrollable_area)
-    : scrollable_area_(&scrollable_area),
-      h_bar_is_attached_(0),
-      v_bar_is_attached_(0) {}
+ScrollbarManager::ScrollbarManager()
+    : h_bar_is_attached_(false), v_bar_is_attached_(false) {}
 
 DEFINE_TRACE(ScrollbarManager) {
-  visitor->Trace(scrollable_area_);
   visitor->Trace(h_bar_);
   visitor->Trace(v_bar_);
 }
 
 void ScrollbarManager::Dispose() {
-  h_bar_is_attached_ = v_bar_is_attached_ = 0;
+  h_bar_is_attached_ = v_bar_is_attached_ = false;
   DestroyScrollbar(kHorizontalScrollbar);
   DestroyScrollbar(kVerticalScrollbar);
 }