Enable Media query evaluation in the preload scanner

Source/core/css/MediaValues.h

Index: Source/core/css/MediaValues.h
diff --git a/Source/core/css/MediaValues.h b/Source/core/css/MediaValues.h
new file mode 100644
index 0000000000000000000000000000000000000000..15fc1af761a3d4fc877428c09fe312cf176f1699
--- /dev/null
+++ b/Source/core/css/MediaValues.h
@@ -0,0 +1,127 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MediaValues_h
+#define MediaValues_h
+
+#include "core/css/MediaQueryEvaluator.h"
+#include "core/css/resolver/StyleResolverState.h"
+#include "core/rendering/style/RenderStyle.h"
+#include "wtf/RefCounted.h"
+#include "wtf/RefPtr.h"
+#include "wtf/text/WTFString.h"
+
+namespace WebCore {
+
+class Document;
+
+class MediaValues : public RefCounted<MediaValues> {
+public:
+    enum MediaValuesMode { CachingMode, DynamicMode };

[abarth-chromium, 2014/03/27 21:01:55]

These should all be on separate lines.

+
+    static PassRefPtr<MediaValues> create(Document*, MediaValuesMode);
+    static PassRefPtr<MediaValues> create(LocalFrame*, RenderStyle*, MediaValuesMode);
+    PassRefPtr<MediaValues> copy() const;
+
+    enum PointerDeviceType { TouchPointer, MousePointer, NoPointer, UnknownPointer };

[abarth-chromium, 2014/03/27 21:01:55]

These too.

+
+    int viewportWidth() const;
+    int viewportHeight() const;
+    int deviceWidth() const;
+    int deviceHeight() const;
+    float devicePixelRatio() const;
+    int colorBitsPerComponent() const;
+    int monochromeBitsPerComponent() const;
+    PointerDeviceType pointer() const;
+    int defaultFontSize() const;
+    bool threeDEnabled() const;
+    bool scanMediaType() const;
+    bool screenMediaType() const;
+    bool printMediaType() const;
+    bool strictMode() const;
+    RenderStyle* style() const { return m_style.get(); }
+    Document* document() const;
+
+    MediaValues(PassRefPtr<RenderStyle> style,
+        LocalFrame* frame,
+        MediaValuesMode mode)

[abarth-chromium, 2014/03/27 21:01:55]

You can merge these three lines though.  :)

+        : m_style(style)
+        , m_frame(frame)
+        , m_mode(mode)
+        , m_viewportWidth(0)
+        , m_viewportHeight(0)
+        , m_deviceWidth(0)
+        , m_deviceHeight(0)
+        , m_devicePixelRatio(0)
+        , m_colorBitsPerComponent(0)
+        , m_monochromeBitsPerComponent(0)
+        , m_pointer(UnknownPointer)
+        , m_defaultFontSize(0)
+        , m_threeDEnabled(false)
+        , m_scanMediaType(false)
+        , m_screenMediaType(false)
+        , m_printMediaType(false)
+        , m_strictMode(false)
+    {
+        ASSERT(mode == DynamicMode);
+    }
+
+    MediaValues(MediaValuesMode mode,
+        int viewportWidth,
+        int viewportHeight,
+        int deviceWidth,
+        int deviceHeight,
+        float devicePixelRatio,
+        int colorBitsPerComponent,
+        int monochromeBitsPerComponent,
+        PointerDeviceType pointer,
+        int defaultFontSize,
+        bool threeDEnabled,
+        bool scanMediaType,
+        bool screenMediaType,
+        bool printMediaType,
+        bool strictMode)
+        : m_frame(0)
+        , m_mode(mode)
+        , m_viewportWidth(viewportWidth)
+        , m_viewportHeight(viewportHeight)
+        , m_deviceWidth(deviceWidth)
+        , m_deviceHeight(deviceHeight)
+        , m_devicePixelRatio(devicePixelRatio)
+        , m_colorBitsPerComponent(colorBitsPerComponent)
+        , m_monochromeBitsPerComponent(monochromeBitsPerComponent)
+        , m_pointer(pointer)
+        , m_defaultFontSize(defaultFontSize)
+        , m_threeDEnabled(threeDEnabled)
+        , m_scanMediaType(scanMediaType)
+        , m_screenMediaType(screenMediaType)
+        , m_printMediaType(printMediaType)
+        , m_strictMode(strictMode)
+    {
+        ASSERT(mode == CachingMode);
+    }
+
+private:
+    RefPtr<RenderStyle> m_style;
+    LocalFrame* m_frame;
+    MediaValuesMode m_mode;
+
+    int m_viewportWidth;

[abarth-chromium, 2014/03/27 21:01:55]

I'd add a comment here explaining that the members below this point need to be
threadsafe because they're copied to another thread.

I'd also add an isSafeToSendToAnotherThread function that checks !m_style,
!m_frame, m_mode == CachingMode, and hasOneRef().  You'll also need to call
isSafeToSendToAnotherThread in the appropriate place in the parser.

+    int m_viewportHeight;
+    int m_deviceWidth;
+    int m_deviceHeight;
+    float m_devicePixelRatio;
+    int m_colorBitsPerComponent;
+    int m_monochromeBitsPerComponent;
+    PointerDeviceType m_pointer;
+    int m_defaultFontSize;
+    bool m_threeDEnabled;
+    bool m_scanMediaType;
+    bool m_screenMediaType;
+    bool m_printMediaType;
+    bool m_strictMode;
+};
+
+} // namespace
+#endif