Implement color-gamut media query

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

Index: third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp
diff --git a/third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp b/third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp
index 5d3f0b3b2bca3c57326b5f36635abce626f18d0a..0efd93b94343f6667727a95298d225ddfed465f5 100644
--- a/third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp
+++ b/third_party/WebKit/Source/core/css/MediaQueryEvaluator.cpp
@@ -51,6 +51,7 @@
 #include "core/style/ComputedStyle.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatRect.h"
+#include "platform/graphics/ColorSpace.h"
 #include "public/platform/PointerProperties.h"
 #include "public/platform/ShapeProperties.h"
 #include "public/platform/WebDisplayMode.h"
@@ -753,6 +754,46 @@ static bool scanMediaFeatureEval(const MediaQueryExpValue& value,
   return (value.id == CSSValueProgressive);
 }
 
+static bool colorGamutMediaFeatureEval(const MediaQueryExpValue& value,
+                                       MediaFeaturePrefix,
+                                       const MediaValues& mediaValues) {
+  // isValid() is false if there is no parameter. Without parameter we should
+  // return true to indicate that colorGamutMediaFeature is enabled in the
+  // browser.
+  if (!value.isValid())
+    return true;
+
+  if (!value.isID)
+    return false;
+
+  DCHECK(value.id == CSSValueSRGB || value.id == CSSValueP3 ||
+         value.id == CSSValueRec2020);
+
+  ColorSpaceGamut gamut = mediaValues.colorGamut();
+  switch (gamut) {
+    case ColorSpaceGamut::Unknown:
+    case ColorSpaceGamut::LessThanNTSC:
+    case ColorSpaceGamut::NTSC:
+    case ColorSpaceGamut::SRGB:
+      return value.id == CSSValueSRGB;
+    case ColorSpaceGamut::AlmostP3:
+    case ColorSpaceGamut::P3:
+    case ColorSpaceGamut::AdobeRGB:
+    case ColorSpaceGamut::Wide:
+      return value.id == CSSValueSRGB || value.id == CSSValueP3;
+    case ColorSpaceGamut::BT2020:
+    case ColorSpaceGamut::ProPhoto:
+    case ColorSpaceGamut::UltraWide:
+      return value.id == CSSValueSRGB || value.id == CSSValueP3 ||
+             value.id == CSSValueRec2020;
+    case ColorSpaceGamut::End:

[Yoav Weiss, 2017/01/27 12:13:38]

Potential nit: Can we use `default:` here and avoid one of the returns?

[mlamouri (slow - plz ping), 2017/01/27 16:54:29]

I prefer to avoid `default` so if a new value gets added, it will fail to
compile. Most compilers will understand that all values of the enum are handled
but every time I try one Android or Microsoft compiler is too dumb. Happy to
give it a shot again :)

[hubbe, 2017/01/27 18:19:37]

I think it would be easier to just do something like:

switch (value.id) {
   case CSSValueP3:
       return gamut >= ColorSpaceGamut::P3;
   ....
}

[mlamouri (slow - plz ping), 2017/01/27 18:54:17]

That is true but because `value.id` isn't a "restricted" enum, new values on
either side (color-gamut MQ or ColorSpaceGamut) could be added without this code
being looked at. The primary goal here is making sure we don't forget about this
code :)

+      NOTREACHED();
+      return false;
+  }
+
+  return false;
+}
+
 void MediaQueryEvaluator::init() {
   // Create the table.
   gFunctionMap = new FunctionMap;