Remove MediaValues' dependency on RenderStyle

Source/core/css/MediaValuesCached.cpp

Index: Source/core/css/MediaValuesCached.cpp
diff --git a/Source/core/css/MediaValuesCached.cpp b/Source/core/css/MediaValuesCached.cpp
index d83a4b919b4bb392e63f6a394e06348971fb12fa..d8888d91ff7dcce488c0f61fc0f46fc4b899f5c6 100644
--- a/Source/core/css/MediaValuesCached.cpp
+++ b/Source/core/css/MediaValuesCached.cpp
@@ -5,7 +5,6 @@
 #include "config.h"
 #include "core/css/MediaValuesCached.h"
 
-#include "core/css/CSSHelper.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/dom/Document.h"
 #include "core/rendering/RenderObject.h"
@@ -20,33 +19,35 @@ PassRefPtr<MediaValues> MediaValuesCached::create(MediaValuesCachedData& data)
 PassRefPtr<MediaValues> MediaValuesCached::create(Document& document)
 {
     Document* executingDocument = getExecutingDocument(document);
-    return MediaValuesCached::create(executingDocument->frame(), executingDocument->renderer()->style());
+    return MediaValuesCached::create(executingDocument->frame());
 }
 
-PassRefPtr<MediaValues> MediaValuesCached::create(LocalFrame* frame, RenderStyle* style)
+PassRefPtr<MediaValues> MediaValuesCached::create(LocalFrame* frame)
 {
-    return adoptRef(new MediaValuesCached(frame, style));
+    return adoptRef(new MediaValuesCached(frame));
 }
 
-MediaValuesCached::MediaValuesCached(LocalFrame* frame, RenderStyle* style)
+MediaValuesCached::MediaValuesCached(LocalFrame* frame)
 {
-    ASSERT(frame && style);
     ASSERT(isMainThread());
-    m_data.viewportWidth = calculateViewportWidth(frame);
-    m_data.viewportHeight = calculateViewportHeight(frame);
-    m_data.deviceWidth = calculateDeviceWidth(frame);
-    m_data.deviceHeight = calculateDeviceHeight(frame);
-    m_data.devicePixelRatio = calculateDevicePixelRatio(frame);
-    m_data.colorBitsPerComponent = calculateColorBitsPerComponent(frame);
-    m_data.monochromeBitsPerComponent = calculateMonochromeBitsPerComponent(frame);
-    m_data.pointer = calculateLeastCapablePrimaryPointerDeviceType(frame);
-    m_data.defaultFontSize = calculateDefaultFontSize(style);
-    m_data.computedFontSize = calculateComputedFontSize(style);
-    m_data.threeDEnabled = calculateThreeDEnabled(frame);
-    m_data.scanMediaType = calculateScanMediaType(frame);
-    m_data.screenMediaType = calculateScreenMediaType(frame);
-    m_data.printMediaType = calculatePrintMediaType(frame);
-    m_data.strictMode = calculateStrictMode(frame);
+    // In case that frame is missing (e.g. for images that their document does not have a frame)
+    // We simply leave the MediaValues object with the default MediaValuesCachedData values.
+    if (frame) {

[eseidel, 2014/04/18 16:50:13]

Early return instead of long indented block?

+        m_data.viewportWidth = calculateViewportWidth(frame);

[eseidel, 2014/04/18 16:50:13]

I almost wonder if this whole construcor shouldn't be replaced with creating a
MediaValuesDynamic and calling a "cachedCopy()" method on it. :)  CLs for
another day.

+        m_data.viewportHeight = calculateViewportHeight(frame);
+        m_data.deviceWidth = calculateDeviceWidth(frame);
+        m_data.deviceHeight = calculateDeviceHeight(frame);
+        m_data.devicePixelRatio = calculateDevicePixelRatio(frame);
+        m_data.colorBitsPerComponent = calculateColorBitsPerComponent(frame);
+        m_data.monochromeBitsPerComponent = calculateMonochromeBitsPerComponent(frame);
+        m_data.pointer = calculateLeastCapablePrimaryPointerDeviceType(frame);
+        m_data.defaultFontSize = calculateDefaultFontSize(frame);
+        m_data.threeDEnabled = calculateThreeDEnabled(frame);
+        m_data.scanMediaType = calculateScanMediaType(frame);
+        m_data.screenMediaType = calculateScreenMediaType(frame);
+        m_data.printMediaType = calculatePrintMediaType(frame);
+        m_data.strictMode = calculateStrictMode(frame);
+    }
 }
 
 MediaValuesCached::MediaValuesCached(const MediaValuesCachedData& data)
@@ -61,68 +62,7 @@ PassRefPtr<MediaValues> MediaValuesCached::copy() const
 
 bool MediaValuesCached::computeLength(double value, unsigned short type, int& result) const
 {
-    // We're running in a background thread, so RenderStyle is not available.
-    // Nevertheless, we can evaluate lengths using cached values.
-    //
-    // The logic in this function is duplicated from CSSPrimitiveValue::computeLengthDouble
-    // because MediaValues::computeLength needs nearly identical logic, but we haven't found a way to make
-    // CSSPrimitiveValue::computeLengthDouble more generic (to solve both cases) without hurting performance.
-
-    // FIXME - Unite the logic here with CSSPrimitiveValue is a performant way.
-    int factor = 0;
-    switch (type) {
-    case CSSPrimitiveValue::CSS_EMS:
-    case CSSPrimitiveValue::CSS_REMS:
-        factor = m_data.defaultFontSize;
-        break;
-    case CSSPrimitiveValue::CSS_PX:
-        factor = 1;
-        break;
-    case CSSPrimitiveValue::CSS_EXS:
-        // FIXME: We have a bug right now where the zoom will be applied twice to EX units.
-        // FIXME: We don't seem to be able to cache fontMetrics related values.
-        // Trying to access them is triggering some sort of microtask. Serving the spec's default instead.
-        factor = m_data.defaultFontSize / 2.0;
-        break;
-    case CSSPrimitiveValue::CSS_CHS:
-        // FIXME: We don't seem to be able to cache fontMetrics related values.
-        // Trying to access them is triggering some sort of microtask. Serving the (future) spec default instead.
-        factor = m_data.defaultFontSize / 2.0;
-        break;
-    case CSSPrimitiveValue::CSS_VW:
-        factor = m_data.viewportWidth / 100;
-        break;
-    case CSSPrimitiveValue::CSS_VH:
-        factor = m_data.viewportHeight / 100;
-        break;
-    case CSSPrimitiveValue::CSS_VMIN:
-        factor = std::min(m_data.viewportWidth, m_data.viewportHeight) / 100;
-        break;
-    case CSSPrimitiveValue::CSS_VMAX:
-        factor = std::max(m_data.viewportWidth, m_data.viewportHeight) / 100;
-        break;
-    case CSSPrimitiveValue::CSS_CM:
-        factor = cssPixelsPerCentimeter;
-        break;
-    case CSSPrimitiveValue::CSS_MM:
-        factor = cssPixelsPerMillimeter;
-        break;
-    case CSSPrimitiveValue::CSS_IN:
-        factor = cssPixelsPerInch;
-        break;
-    case CSSPrimitiveValue::CSS_PT:
-        factor = cssPixelsPerPoint;
-        break;
-    case CSSPrimitiveValue::CSS_PC:
-        factor = cssPixelsPerPica;
-        break;
-    default:
-        return false;
-    }
-
-    ASSERT(factor > 0);
-    result = roundForImpreciseConversion<int>(value*factor);
-    return true;
+    return MediaValues::computeLength(value, type, m_data.defaultFontSize, m_data.viewportWidth, m_data.viewportHeight, result);
 }
 
 bool MediaValuesCached::isSafeToSendToAnotherThread() const