Make some updates to BM bar for MD.

ui/gfx/color_utils.cc

Index: ui/gfx/color_utils.cc
diff --git a/ui/gfx/color_utils.cc b/ui/gfx/color_utils.cc
index 65d0fa252d43a85fa9dfcf46a98b3b86beb7393f..c2f1b3f974d67b22d3d73df32a3b7bcb572e5450 100644
--- a/ui/gfx/color_utils.cc
+++ b/ui/gfx/color_utils.cc
@@ -78,6 +78,10 @@ double ContrastRatio(double foreground_luminance, double background_luminance) {
 
 // ----------------------------------------------------------------------------
 
+double GetContrastRatio(SkColor color_a, SkColor color_b) {
+  return ContrastRatio(RelativeLuminance(color_a), RelativeLuminance(color_b));
+}
+
 unsigned char GetLuminanceForColor(SkColor color) {
   return base::saturated_cast<unsigned char>(
       (0.3 * SkColorGetR(color)) +