Add a hook to inject trusted Cast roots for testing purposes.

extensions/common/cast/cast_cert_validator.h

Index: extensions/common/cast/cast_cert_validator.h
diff --git a/extensions/common/cast/cast_cert_validator.h b/extensions/common/cast/cast_cert_validator.h
index c435ebb8776f312edfb7c6bee440f028175c6d4f..dfc945ee7ba2ac93c30479fc4359d9de32d9e648 100644
--- a/extensions/common/cast/cast_cert_validator.h
+++ b/extensions/common/cast/cast_cert_validator.h
@@ -86,6 +86,14 @@ bool VerifyDeviceCert(const std::vector<std::string>& certs,
 scoped_ptr<CertVerificationContext> CertVerificationContextImplForTest(
     const base::StringPiece& spki);
 
+// Exposed only for testing, not for use in production code.
+//
+// Injects trusted root certificates into the CastTrustStore.
+// |data| must remain valid throughout the lifetime of the program.

[eroman, 2016/04/22 20:03:19]

nit: "and not be mutated"

[ryanchung, 2016/04/22 22:06:02]

Done.

+// Warning: Using this function concurrently with VerifyDeviceCert()
+//          is not thread safe.
+bool AddTrustAnchorForTest(const uint8_t* data,
+                           size_t length) WARN_UNUSED_RESULT;
 
 }  // namespace cast_crypto
 }  // namespace api