Disable overlay scrollbars to hide them on non-Mac.

third_party/WebKit/Source/core/testing/Internals.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 119 matching lines @@
 #include "platform/InstanceCounters.h"
 #include "platform/Language.h"
 #include "platform/LayoutLocale.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/heap/Handle.h"
 #include "platform/network/ResourceLoadPriority.h"
 #include "platform/scroll/ProgrammaticScrollAnimator.h"
+#include "platform/scroll/ScrollbarTheme.h"
 #include "platform/testing/URLTestHelpers.h"
 #include "platform/tracing/TraceEvent.h"
 #include "platform/weborigin/SchemeRegistry.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebConnectionType.h"
 #include "public/platform/WebGraphicsContext3DProvider.h"
 #include "public/platform/WebLayer.h"
 #include "public/platform/modules/remoteplayback/WebRemotePlaybackAvailability.h"
 #include "wtf/InstanceCounter.h"
 #include "wtf/Optional.h"
@@ skipping 2871 matching lines @@
   return ClientRectList::create(rects);
 }
 
 void Internals::setCapsLockState(bool enabled) {
   KeyboardEventManager::setCurrentCapsLockState(
       enabled ? OverrideCapsLockState::On : OverrideCapsLockState::Off);
 }
 
 bool Internals::setScrollbarVisibilityInScrollableArea(Node* node,
                                                        bool visible) {
-  if (ScrollableArea* scrollableArea = scrollableAreaForNode(node))
-    return scrollableArea->scrollAnimator().setScrollbarsVisibleForTesting(
-        visible);
+  if (ScrollableArea* scrollableArea = scrollableAreaForNode(node)) {
+    scrollableArea->setScrollbarsHidden(!visible);
+    scrollableArea->scrollAnimator().setScrollbarsVisibleForTesting(visible);
+    return ScrollbarTheme::theme().usesOverlayScrollbars();
+  }
   return false;
 }
 
 double Internals::monotonicTimeToZeroBasedDocumentTime(
     double platformTime,
     ExceptionState& exceptionState) {
   Document* document = contextDocument();
   if (!document) {
     exceptionState.throwDOMException(InvalidAccessError,
                                      "No context document is available.");
@@ skipping 35 matching lines @@
     return ClientRect::create();
 
   return ClientRect::create(FloatRect(node->layoutObject()->visualRect()));
 }
 
 void Internals::crash() {
   CHECK(false) << "Intentional crash";
 }
 
 }  // namespace blink