Scale scrollbar in use-zoom-for-dsf mode

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

 /*
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  *
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  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
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  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
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  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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 #include "platform/scroll/Scrollbar.h"
 
 #include <algorithm>
+#include "platform/HostWindow.h"
 #include "platform/PlatformGestureEvent.h"
 #include "platform/PlatformMouseEvent.h"
 #include "platform/graphics/paint/CullRect.h"
 // See windowActiveChangedForSnowLeopardOnly() below.
 // TODO(ellyjones): remove this when Snow Leopard support is gone.
 #if OS(MACOSX)
 #include "platform/mac/VersionUtilMac.h"
 #endif
 #include "platform/scroll/ScrollAnimatorBase.h"
 #include "platform/scroll/ScrollableArea.h"
 #include "platform/scroll/ScrollbarTheme.h"
 
 namespace blink {
 
-PassRefPtrWillBeRawPtr<Scrollbar> Scrollbar::create(ScrollableArea* scrollableArea, ScrollbarOrientation orientation, ScrollbarControlSize size)
+PassRefPtrWillBeRawPtr<Scrollbar> Scrollbar::create(ScrollableArea* scrollableArea, ScrollbarOrientation orientation, ScrollbarControlSize size, HostWindow* hostWindow)
 {
-    return adoptRefWillBeNoop(new Scrollbar(scrollableArea, orientation, size));
+    return adoptRefWillBeNoop(new Scrollbar(scrollableArea, orientation, size, hostWindow));
 }
 
 PassRefPtrWillBeRawPtr<Scrollbar> Scrollbar::createForTesting(ScrollableArea* scrollableArea, ScrollbarOrientation orientation, ScrollbarControlSize size, ScrollbarTheme* theme)
 {
-    return adoptRefWillBeNoop(new Scrollbar(scrollableArea, orientation, size, theme));
+    return adoptRefWillBeNoop(new Scrollbar(scrollableArea, orientation, size, nullptr, theme));
 }
 
-Scrollbar::Scrollbar(ScrollableArea* scrollableArea, ScrollbarOrientation orientation, ScrollbarControlSize controlSize, ScrollbarTheme* theme)
+Scrollbar::Scrollbar(ScrollableArea* scrollableArea, ScrollbarOrientation orientation, ScrollbarControlSize controlSize, HostWindow* hostWindow, ScrollbarTheme* theme)
     : m_scrollableArea(scrollableArea)
     , m_orientation(orientation)
     , m_controlSize(controlSize)
     , m_theme(theme ? *theme : ScrollbarTheme::theme())
     , m_visibleSize(0)
     , m_totalSize(0)
     , m_currentPos(0)
     , m_dragOrigin(0)
     , m_hoveredPart(NoPart)
     , m_pressedPart(NoPart)
     , m_pressedPos(0)
     , m_scrollPos(0)
     , m_draggingDocument(false)
     , m_documentDragPos(0)
     , m_enabled(true)
     , m_scrollTimer(this, &Scrollbar::autoscrollTimerFired)
     , m_overlapsResizer(false)
     , m_elasticOverscroll(0)
     , m_trackNeedsRepaint(true)
     , m_thumbNeedsRepaint(true)
 {
     m_theme.registerScrollbar(*this);
 
     // FIXME: This is ugly and would not be necessary if we fix cross-platform code to actually query for
     // scrollbar thickness and use it when sizing scrollbars (rather than leaving one dimension of the scrollbar
     // alone when sizing).
     int thickness = m_theme.scrollbarThickness(controlSize);
+    if (hostWindow) {
+        // Convert the thickness in the screen (dip) to the viewport
+        // by applying the invert of the viewport to screen scale.
+        // TODO(oshima): Introduce the screenToViewport(float) to avoid the rounding error.
+        IntRect inScreen(0, 0, 100, 0);
+        inScreen = hostWindow->viewportToScreen(inScreen);
+        thickness *= 100.f / inScreen.width();
+    }
+
     Widget::setFrameRect(IntRect(0, 0, thickness, thickness));
 
     m_currentPos = scrollableAreaCurrentPos();
 }
 
 Scrollbar::~Scrollbar()
 {
     m_theme.unregisterScrollbar(*this);
 }
 
@@ skipping 462 matching lines @@
         invalidParts = AllParts;
     if (invalidParts & ~ThumbPart)
         m_trackNeedsRepaint = true;
     if (invalidParts & ThumbPart)
         m_thumbNeedsRepaint = true;
     if (m_scrollableArea)
         m_scrollableArea->setScrollbarNeedsPaintInvalidation(orientation());
 }
 
 } // namespace blink