Fix buffer overflow due to unbounded strlen over a non-null terminated string. Detected by asan.

extensions/browser/api/cast_channel/cast_auth_util.cc

Index: extensions/browser/api/cast_channel/cast_auth_util.cc
diff --git a/extensions/browser/api/cast_channel/cast_auth_util.cc b/extensions/browser/api/cast_channel/cast_auth_util.cc
index e2beca1870179241a76f4a2aab586859b8fca55b..3377a2fb129ba5cf2bc1b5b6910a75e026a88137 100644
--- a/extensions/browser/api/cast_channel/cast_auth_util.cc
+++ b/extensions/browser/api/cast_channel/cast_auth_util.cc
@@ -137,8 +137,11 @@ AuthResult AuthenticateChallengeReply(const CastMessage& challenge_reply,
     return result;
   }
 
-  if (response.client_auth_certificate().find(reinterpret_cast<const char*>(
-          kAudioOnlyPolicy)) != std::string::npos) {
+  std::string audio_policy =

[mark a. foltz, 2015/01/30 00:22:42]

const std::string& 

[Kevin M, 2015/01/30 22:15:47]

I didn't know this was legal. Cool.

+      std::string(reinterpret_cast<const char*>(kAudioOnlyPolicy),
+                  (arraysize(kAudioOnlyPolicy) / sizeof(unsigned char)));
+  if (response.client_auth_certificate().find(audio_policy) !=
+      std::string::npos) {
     result.channel_policies |= AuthResult::POLICY_AUDIO_ONLY;
   }