Add ability to constrain dominant color selection to a HSL range.

ui/gfx/color_utils.h

Index: ui/gfx/color_utils.h
diff --git a/ui/gfx/color_utils.h b/ui/gfx/color_utils.h
index 6dd6300aa3bab7abdaaab1cbab3e15a3f1fbae22..18bb2c218f287ae8f956b6b4d8942791ab4e19e5 100644
--- a/ui/gfx/color_utils.h
+++ b/ui/gfx/color_utils.h
@@ -29,6 +29,20 @@ GFX_EXPORT double RelativeLuminance(SkColor color);
 GFX_EXPORT void SkColorToHSL(SkColor c, HSL* hsl);
 GFX_EXPORT SkColor HSLToSkColor(const HSL& hsl, SkAlpha alpha);
 
+// Determines whether the given |hsl| falls within the given range for each
+// component.
+//
+// Any components of |lower_bound| or |upper_bound| that are -1 will be
+// ignored.

[Matt Giuca, 2014/05/22 05:03:52]

This could be construed as "the component will be extended to its logical
limit."

For example, if lower_bound.s = -1 and upper_bound.s = 0.4, I might expect it to
ignore lower_bound, but still apply upper_bound (so effectively be checking s in
[0.0, 0.4]). That's not the case with your algorithm -- if either lower or upper
is -1, the entire attribute is ignored. Either fix the comment or the code.

Also, don't say "that are -1", say "that are negative".

[calamity, 2014/05/22 07:36:36]

Done.

+//
+// For hue, the lower bound should be in the range [0, 1] and the upper bound
+// should be in the range [(lower bound), (lower bound + 1)].
+// For saturation and value, bounds should be specified in the range [0, 1],
+// with the lower bound less than the upper bound.
+GFX_EXPORT bool IsWithinHSLRange(const HSL& hsl,
+                                 const HSL& lower_bound,
+                                 const HSL& upper_bound);
+
 // HSL-Shift an SkColor. The shift values are in the range of 0-1, with the
 // option to specify -1 for 'no change'. The shift values are defined as:
 // hsl_shift[0] (hue): The absolute hue value - 0 and 1 map