views: refactor away PlatformStyle::BackgroundColorForMdButton

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 fc8b44652869e4d8c678aff83420c0db416f8f4e..9ed814ddad4cad9489f573ea654c4786cd03d700 100644
--- a/ui/gfx/color_utils.h
+++ b/ui/gfx/color_utils.h
@@ -94,6 +94,11 @@ GFX_EXPORT double CalculateBoringScore(const SkBitmap& bitmap);
 GFX_EXPORT SkColor AlphaBlend(SkColor foreground, SkColor background,
                               SkAlpha alpha);
 
+// Returns an AlphaBlend of the specified colors, using the alpha component of
+// the foreground color for the alpha and with the alpha of the foreground color

[Evan Stade, 2016/09/08 14:50:47]

I think the most intuitive way to explain this might be:

"Returns the color that results from painting |foreground| on top of
|background|."

[Elly Fong-Jones, 2016/09/08 16:06:12]

Done.

+// set to 1.0.
+GFX_EXPORT SkColor ImplicitAlphaBlend(SkColor foreground, SkColor background);
+
 // Returns true if the luma of |color| is closer to black than white.
 GFX_EXPORT bool IsDark(SkColor color);