Hook up Android closed captions 'enabled' setting to Blink

Add an API for the Android closed captions state change to be
plumbed down to Blink.

Blink-side CL: https://codereview.chromium.org/1118613002/

BUG=457850, 388588

Review URL: https://codereview.chromium.org/1110103004

Cr-Commit-Position: refs/heads/master@{#338350}
diff --git a/AUTHORS b/AUTHORS
index b5bbb40d..6f15199 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -529,6 +529,7 @@
 Sungguk Lim <[email protected]>
 Sungmann Cho <[email protected]>
 Sungmann Cho <[email protected]>
+Sunitha Srivatsa <[email protected]>
 Suyash Sengar <[email protected]>
 Sunil Ratnu <[email protected]>
 Swati Jaiswal <[email protected]>