[MD] replace infobar bottom solid line separator with a shadow.

ui/gfx/skia_util.cc

Index: ui/gfx/skia_util.cc
diff --git a/ui/gfx/skia_util.cc b/ui/gfx/skia_util.cc
index a971c9f22ecbe483a13e07a509fd13bca8aa469d..7d554696ad4cdba237a609da569d689ef8f5fc03 100644
--- a/ui/gfx/skia_util.cc
+++ b/ui/gfx/skia_util.cc
@@ -130,7 +130,7 @@ skia::RefPtr<SkShader> CreateGradientShader(int start_point,
   grad_points[1].iset(0, end_point);
 
   return skia::AdoptRef(SkGradientShader::CreateLinear(
-      grad_points, grad_colors, NULL, 2, SkShader::kRepeat_TileMode));
+      grad_points, grad_colors, NULL, 2, SkShader::kClamp_TileMode));

[sky, 2016/03/16 15:39:42]

Why does this change matter?

[Evan Stade, 2016/03/16 19:29:52]

ASCII art of what we want is something like:

---------------------
black 10%
black 10%
black 10%
black 10%
black 8%
black 6%
black 4%
black 2%
black 0%
---------------------

So we define the middle gradient point and the final gradient point. Clamp means
the black 10% is then repeated all the way to the top edge. With tile, this
would end up looking something like

---------------------
black 4%
black 2%
black 0%
black 10%
black 8%
black 6%
black 4%
black 2%
black 0%
---------------------

[sky, 2016/03/16 21:56:55]

Are you sure other call sites don't want the current behavior?

 }
 
 static SkScalar RadiusToSigma(double radius) {