Revert of Memoize LayoutTheemDefault::clampedMenuListArrowPaddingSize()....

Revert of Memoize LayoutTheemDefault::clampedMenuListArrowPaddingSize(). (patchset #1 id:1 of https://codereview.chromium.org/2600873002/ )

Reason for revert:
This appears to be causing the layout test failures in crbug.com/678684.  (Ran a local bisect to find the culprit.)

Original issue's description:
> Memoize LayoutTheemDefault::clampedMenuListArrowPaddingSize().
>
> This is the second try to fix a performance regression of menulist rendering.
> The first try [1] didn't have major improvement. This CL reverts it, and cache
> another value.
>
> [1] crrev.com/438496
>
> BUG=673754
>
> Committed: https://crrev.com/b1f1c5d7ee4bfe822c4c0a384a9ac2ddaa71554f
> Cr-Commit-Position: refs/heads/master@{#441569}

TBR=keishi@chromium.org,tkent@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=673754

Review-Url: https://codereview.chromium.org/2612113003
Cr-Commit-Position: refs/heads/master@{#441739}

third_party/WebKit/Source/core/layout/LayoutThemeDefault.cpp

@@ -336,36 +336,31 @@ int LayoutThemeDefault::popupInternalPaddingBottom(
 }
 
 int LayoutThemeDefault::menuListArrowWidthInDIP() const {
+  if (m_menuListArrowWidthInDIP > 0)
+    return m_menuListArrowWidthInDIP;
   int width = Platform::current()
                   ->themeEngine()
                   ->getSize(WebThemeEngine::PartScrollbarUpArrow)
                   .width;
-  return width > 0 ? width : 15;
+  const_cast<LayoutThemeDefault*>(this)->m_menuListArrowWidthInDIP =
+      width > 0 ? width : 15;
+  return m_menuListArrowWidthInDIP;
 }
 
 float LayoutThemeDefault::clampedMenuListArrowPaddingSize(
     const HostWindow* host,
     const ComputedStyle& style) const {
-  if (m_cachedMenuListArrowPaddingSize > 0 &&
-      style.effectiveZoom() == m_cachedMenuListArrowZoomLevel)
-    return m_cachedMenuListArrowPaddingSize;
-  m_cachedMenuListArrowZoomLevel = style.effectiveZoom();
   int originalSize = menuListArrowWidthInDIP();
   int scaledSize =
       host ? host->windowToViewportScalar(originalSize) : originalSize;
   // The result should not be samller than the scrollbar thickness in order to
   // secure space for scrollbar in popup.
   float deviceScale = 1.0f * scaledSize / originalSize;
-  float size;
-  if (m_cachedMenuListArrowZoomLevel < deviceScale) {
-    size = scaledSize;
-  } else {
-    // The value should be zoomed though scrollbars aren't scaled by zoom.
-    // crbug.com/432795.
-    size = originalSize * m_cachedMenuListArrowZoomLevel;
-  }
-  m_cachedMenuListArrowPaddingSize = size;
-  return size;
+  if (style.effectiveZoom() < deviceScale)
+    return scaledSize;
+  // The value should be zoomed though scrollbars aren't scaled by zoom.
+  // crbug.com/432795.
+  return originalSize * style.effectiveZoom();
 }
 
 // static

third_party/WebKit/Source/core/layout/LayoutThemeDefault.h

@@ -159,9 +159,7 @@ class CORE_EXPORT LayoutThemeDefault : public LayoutTheme {
   static unsigned m_inactiveSelectionForegroundColor;
 
   ThemePainterDefault m_painter;
-  // Cached values for crbug.com/673754.
-  mutable float m_cachedMenuListArrowZoomLevel = 0;
-  mutable float m_cachedMenuListArrowPaddingSize = 0;
+  int m_menuListArrowWidthInDIP = 0;
 };
 
 }  // namespace blink