[Linux] Enable subpixel text on high-dpi regardless of hinting

Source/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 179 matching lines @@
         return alpha > 255 ? 255 : alpha;
     }
 
     void setImageInterpolationQuality(InterpolationQuality quality) { mutableState()->setInterpolationQuality(quality); }
     InterpolationQuality imageInterpolationQuality() const { return immutableState()->interpolationQuality(); }
 
     void setCompositeOperation(CompositeOperator, blink::WebBlendMode = blink::WebBlendModeNormal);
     CompositeOperator compositeOperation() const { return immutableState()->compositeOperator(); }
     blink::WebBlendMode blendModeOperation() const { return immutableState()->blendMode(); }
 
-    // Change the way document markers are rendered.
-    // Any deviceScaleFactor higher than 1.5 is enough to justify setting this flag.
-    void setUseHighResMarkers(bool isHighRes) { m_useHighResMarker = isHighRes; }
+    // Speicy the device scale factor which may change the way document markers
+    // and fonts are rendered.
+    void setDeviceScaleFactor(float factor) { m_deviceScaleFactor = factor; }
+    float deviceScaleFactor() const { return m_deviceScaleFactor; }
 
     // If true we are (most likely) rendering to a web page and the
     // canvas has been prepared with an opaque background. If false,
     // the canvas may have transparency (as is the case when rendering
     // to a canvas object).
     void setCertainlyOpaque(bool isOpaque) { m_isCertainlyOpaque = isOpaque; }
     bool isCertainlyOpaque() const { return m_isCertainlyOpaque; }
 
     // Returns if the context is a printing context instead of a display
     // context. Bitmap shouldn't be resampled when printing to keep the best
@@ skipping 293 matching lines @@
     bool m_disableDestructionChecks;
 #endif
     // Tracks the region painted opaque via the GraphicsContext.
     OpaqueRegionSkia m_opaqueRegion;
 
     // Tracks the region where text is painted via the GraphicsContext.
     SkRect m_textRegion;
 
     unsigned m_disabledState;
 
+    float m_deviceScaleFactor;
+
     // Activation for the above region tracking features
     bool m_trackOpaqueRegion : 1;
     bool m_trackTextRegion : 1;
 
-    // Are we on a high DPI display? If so, spelling and grammar markers are larger.
-    bool m_useHighResMarker : 1;
     // FIXME: Make this go away: crbug.com/236892
     bool m_updatingControlTints : 1;
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
     bool m_antialiasHairlineImages : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext_h