Adding code to calculate Underline Thickness from Font Metrics, this will be useful when Skia is used with Blink/Chrome. Blink changes are uploaded with code change in patch https://codereview.chromium.org/147703002/

BUG=skia:
R=reed@android.com, edisonn@google.com, reed@google.com, mtklein@google.com, mtklein@chromium.org, bungeman@google.com

Author: h.joshi@samsung.com

Review URL: https://codereview.chromium.org/152073003

git-svn-id: http://skia.googlecode.com/svn/trunk@13635 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/AUTHORS b/AUTHORS
index a51e7c6..4bef933 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -17,5 +17,6 @@
 Google Inc. <*@google.com>
 Intel <*@intel.com>
 NVIDIA <*@nvidia.com>
+Samsung <*@samsung.com>
 The Chromium Authors <*@chromium.org>
 Thiago Fransosi Farina <thiago.farina@gmail.com>