Add decrypt-only external clear key browser tests.

chrome/test/data/media/encrypted_media_utils.js

Index: chrome/test/data/media/encrypted_media_utils.js
diff --git a/chrome/test/data/media/encrypted_media_utils.js b/chrome/test/data/media/encrypted_media_utils.js
index b7fece4ca49e119f726f0d0156020b32b1beb9e3..e97f0928675fb07e25322018df7e9ef3b83d2529 100644
--- a/chrome/test/data/media/encrypted_media_utils.js
+++ b/chrome/test/data/media/encrypted_media_utils.js
@@ -15,6 +15,8 @@ var KEY_ID = getInitDataFromKeyId("0123456789012345");
 // Heart beat message header.
 var HEART_BEAT_HEADER = 'HEARTBEAT';
 var EXTERNAL_CLEAR_KEY_KEY_SYSTEM = "org.chromium.externalclearkey";
+var DECRYPT_ONLY_EXTERNAL_CLEAR_KEY_KEY_SYSTEM =

[ddorwin, 2013/11/21 04:10:58]

we don't need this (see below)

[xhwang, 2013/11/22 01:47:36]

Done.

+    "org.chromium.externalclearkey.decryptonly";
 // Note that his URL has been normalized from the one in clear_key_cdm.cc.
 var EXTERNAL_CLEAR_KEY_HEARTBEAT_URL =
     'http://test.externalclearkey.chromium.org/';
@@ -105,7 +107,8 @@ function loadEncryptedMedia(video, mediaFile, keySystem, key, useMSE,
 
   function verifyHeartbeatMessage(e) {
     // Only External Clear Key sends a HEARTBEAT message.
-    if (e.keySystem != EXTERNAL_CLEAR_KEY_KEY_SYSTEM) {
+    if (e.keySystem != EXTERNAL_CLEAR_KEY_KEY_SYSTEM &&
+        e.keySystem != DECRYPT_ONLY_EXTERNAL_CLEAR_KEY_KEY_SYSTEM) {

[ddorwin, 2013/11/21 04:10:58]

Just check the beginning.

[xhwang, 2013/11/22 01:47:36]

Done.

       failTest('Unexpected heartbeat from ' + e.keySystem);
       return;
     }