arc: Support non-standard display scale factors.

ui/gfx/image/image_skia.h

Index: ui/gfx/image/image_skia.h
diff --git a/ui/gfx/image/image_skia.h b/ui/gfx/image/image_skia.h
index db7447d986c08a497371523456e372544a5d21be..13391d046c078230d7084497af7dcd8042f99640 100644
--- a/ui/gfx/image/image_skia.h
+++ b/ui/gfx/image/image_skia.h
@@ -75,6 +75,11 @@ class GFX_EXPORT ImageSkia {
   // Returns the maximum scale supported by this platform.
   static float GetMaxSupportedScale();
 
+  // Maps to the closest supported scale. In case scale is greater than the

[msw, 2017/05/24 21:44:18]

nit: This is worded a bit awkwardly; consider something like "Maps to the
closest supported scale. Returns an exact match, a smaller scale within 0.2
units, the nearest larger scale, or the min/max supported scale."

[khmel, 2017/05/26 15:34:53]

Done.

+  // nearest supported scale not more than 0.2 then lowest supported scale is
+  // used otherwise scale is mapped to upper supported scale.
+  static float MapToSupportedScale(float scale);
+
   // Creates an image from the passed in bitmap.
   // DIP width and height are based on scale factor of 1x.
   // Adds ref to passed in bitmap.
@@ -141,7 +146,7 @@ class GFX_EXPORT ImageSkia {
   const SkBitmap* bitmap() const { return &GetBitmap(); }
 
   // Returns a vector with the image reps contained in this object.
-  // There is no guarantee that this will return all images rep for
+  // There is no guarantee that this will r+images rep for

[msw, 2017/05/24 21:44:18]

fix

[khmel, 2017/05/26 15:34:53]

Done.

   // supported scale factors.
   std::vector<gfx::ImageSkiaRep> image_reps() const;