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..5ea6a3e3325a088609d106a7af8eec8501e1c45f 100644
--- a/extensions/browser/api/cast_channel/cast_auth_util.cc
+++ b/extensions/browser/api/cast_channel/cast_auth_util.cc
@@ -20,7 +20,7 @@ namespace {
 
 const char* const kParseErrorPrefix = "Failed to parse auth message: ";
 
-const unsigned char kAudioOnlyPolicy[] =
+const char kAudioOnlyPolicy[] =

[mark a. foltz, 2015/01/29 19:43:08]

This has to remain unsigned right?  It breaks compilation on Windows.

FAILED: ninja -t msvc -e environment.x86 -- E:\b\build\goma/gomacc
"E:\b\depot_tools\win_toolchain\vs2013_files\VC\bin\amd64_x86\cl.exe" /nologo
/showIncludes /FC
@obj\extensions\browser\api\cast_channel\extensions_browser.cast_auth_util.obj.rsp
/c ..\..\extensions\browser\api\cast_channel\cast_auth_util.cc
/Foobj\extensions\browser\api\cast_channel\extensions_browser.cast_auth_util.obj
/Fdobj\extensions\extensions_browser.cc.pdb 
e:\b\build\slave\win\build\src\extensions\browser\api\cast_channel\cast_auth_util.cc(24)
: error C2220: warning treated as error - no 'object' file generated
e:\b\build\slave\win\build\src\extensions\browser\api\cast_channel\cast_auth_util.cc(24)
: warning C4309: 'initializing' : truncation of constant value
ninja: build stopped: subcommand failed.

[Kevin M, 2015/01/30 00:11:10]

Done.

     {0x06, 0x0A, 0x2B, 0x06, 0x01, 0x04, 0x01, 0xD6, 0x79, 0x02, 0x05, 0x02};
 
 namespace cast_crypto = ::extensions::core_api::cast_crypto;
@@ -137,8 +137,9 @@ AuthResult AuthenticateChallengeReply(const CastMessage& challenge_reply,
     return result;
   }
 
-  if (response.client_auth_certificate().find(reinterpret_cast<const char*>(
-          kAudioOnlyPolicy)) != std::string::npos) {
+  if (response.client_auth_certificate().find(std::string(

[mark a. foltz, 2015/01/29 19:43:08]

For readability, consider declaring a separate const std::string& audioPolicy. 
Don't feel strongly though.

[Kevin M, 2015/01/30 00:11:10]

Done.

+          kAudioOnlyPolicy, (arraysize(kAudioOnlyPolicy) /

[mark a. foltz, 2015/01/29 19:43:08]

Extra ()

[Kevin M, 2015/01/30 00:11:10]

Done.

+                             sizeof(unsigned char)))) != std::string::npos) {
     result.channel_policies |= AuthResult::POLICY_AUDIO_ONLY;
   }