Don't change layout size due to top control show/hide

third_party/WebKit/Source/core/css/CSSToLengthConversionData.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 50 matching lines @@
     return m_font->fontMetrics().xHeight();
 }
 
 float CSSToLengthConversionData::FontSizes::ch() const
 {
     ASSERT(m_font);
     return m_font->fontMetrics().zeroWidth();
 }
 
 CSSToLengthConversionData::ViewportSize::ViewportSize(const LayoutView* layoutView)
-    : m_width(layoutView ? layoutView->layoutViewportWidth() : 0)
-    , m_height(layoutView ? layoutView->layoutViewportHeight() : 0)
+    : m_width(layoutView ? layoutView->viewportSizeForViewportUnits().width() : 0)

[jbroman, 2016/01/20 15:44:28]

viewportSizeForViewportUnits seems not free to do twice. Why not store a
DoubleSize internally, and then construct it as:

: m_size(layoutView ? layoutView->viewportSizeForViewportUnits() : 0)

[bokan, 2016/01/20 16:41:10]

Done.

+    , m_height(layoutView ? layoutView->viewportSizeForViewportUnits().height() : 0)
 {
 }
 
 CSSToLengthConversionData::CSSToLengthConversionData(const ComputedStyle* style, const FontSizes& fontSizes, const ViewportSize& viewportSize, float zoom)
     : m_style(style)
     , m_fontSizes(fontSizes)
     , m_viewportSize(viewportSize)
     , m_zoom(clampTo<float>(zoom, std::numeric_limits<float>::denorm_min()))
 {
     ASSERT(m_style);
@@ skipping 84 matching lines @@
     case CSSPrimitiveValue::UnitType::Chs:
         return value * chFontSize();
 
     default:
         ASSERT_NOT_REACHED();
         return 0;
     }
 }
 
 } // namespace blink