Let page zoom affect resolution and -webkit-device-pixel-ratio MQs.

Source/core/css/MediaQueryEvaluator.cpp

 /*
  * CSS Media Query Evaluator
  *
  * Copyright (C) 2006 Kimmo Kinnunen <kimmo.t.kinnunen@nokia.com>.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ skipping 254 matching lines @@
         return compareAspectRatioValue(value, static_cast<int>(sg.width()), static_cast<int>(sg.height()), op);
     }
 
     // ({,min-,max-}device-aspect-ratio)
     // assume if we have a device, its aspect ratio is non-zero
     return true;
 }
 
 static bool evalResolution(CSSValue* value, Frame* frame, MediaFeaturePrefix op)
 {
-    // FIXME: Possible handle other media types than 'screen' and 'print'.
-    float deviceScaleFactor = 0;
+    // FIXME: Possibly handle other media types than 'screen' and 'print'.
+    float actualResolution = 0;
 
     // This checks the actual media type applied to the document, and we know
     // this method only got called if this media type matches the one defined
     // in the query. Thus, if if the document's media type is "print", the
     // media type of the query will either be "print" or "all".
     String mediaType = frame->view()->mediaType();
     if (equalIgnoringCase(mediaType, "screen"))
-        deviceScaleFactor = frame->page()->deviceScaleFactor();
+        actualResolution = frame->resolutionDPPX();

[eae, 2013/08/14 15:20:49]

Why not use devicePixelRatio directly here?

[rune, 2013/08/14 15:59:34]

Do you mean the one in DOMWindow?

It felt more natural to do implement devicePixelRatio/resolutionDPPX in Frame
instead of going Frame -> DOMWindow -> Frame.

     else if (equalIgnoringCase(mediaType, "print")) {
         // The resolution of images while printing should not depend on the DPI
         // of the screen. Until we support proper ways of querying this info
         // we use 300px which is considered minimum for current printers.
-        deviceScaleFactor = 300 / cssPixelsPerInch;
+        actualResolution = 300 / cssPixelsPerInch;
     }
 
     if (!value)
-        return !!deviceScaleFactor;
+        return !!actualResolution;
 
     if (!value->isPrimitiveValue())
         return false;
 
     CSSPrimitiveValue* resolution = toCSSPrimitiveValue(value);
 
     if (resolution->isNumber())
-        return compareValue(deviceScaleFactor, resolution->getFloatValue(), op);
+        return compareValue(actualResolution, resolution->getFloatValue(), op);
 
     if (!resolution->isResolution())
         return false;
 
     if (resolution->isDotsPerCentimeter()) {
         // To match DPCM to DPPX values, we limit to 2 decimal points.
         // The http://dev.w3.org/csswg/css3-values/#absolute-lengths recommends
         // "that the pixel unit refer to the whole number of device pixels that best
         // approximates the reference pixel". With that in mind, allowing 2 decimal
         // point precision seems appropriate.
         return compareValue(
-            floorf(0.5 + 100 * deviceScaleFactor) / 100,
+            floorf(0.5 + 100 * actualResolution) / 100,
             floorf(0.5 + 100 * resolution->getFloatValue(CSSPrimitiveValue::CSS_DPPX)) / 100, op);
     }
 
-    return compareValue(deviceScaleFactor, resolution->getFloatValue(CSSPrimitiveValue::CSS_DPPX), op);
+    return compareValue(actualResolution, resolution->getFloatValue(CSSPrimitiveValue::CSS_DPPX), op);
 }
 
 static bool devicePixelRatioMediaFeatureEval(CSSValue *value, RenderStyle*, Frame* frame, MediaFeaturePrefix op)
 {
     return (!value || toCSSPrimitiveValue(value)->isNumber()) && evalResolution(value, frame, op);
 }
 
 static bool resolutionMediaFeatureEval(CSSValue* value, RenderStyle*, Frame* frame, MediaFeaturePrefix op)
 {
     return (!value || toCSSPrimitiveValue(value)->isResolution()) && evalResolution(value, frame, op);
@@ skipping 358 matching lines @@
     // and let trampoline functions override the prefix if prefix is
     // used
     EvalFunc func = gFunctionMap->get(expr->mediaFeature().impl());
     if (func)
         return func(expr->value(), m_style.get(), m_frame, NoPrefix);
 
     return false;
 }
 
 } // namespace