Revert of Cast device revocation checking.

components/cast_certificate/cast_cert_validator_test_helpers.h

Index: components/cast_certificate/cast_cert_validator_test_helpers.h
diff --git a/components/cast_certificate/cast_cert_validator_test_helpers.h b/components/cast_certificate/cast_cert_validator_test_helpers.h
index 72cb5034a19649deeb17cc7e3fe00c2f8487f770..d5281a70707518f5dd68035897d96e58aed5d79c 100644
--- a/components/cast_certificate/cast_cert_validator_test_helpers.h
+++ b/components/cast_certificate/cast_cert_validator_test_helpers.h
@@ -35,10 +35,6 @@
 // |file_name| should be relative to //components/test/data/cast_certificate
 SignatureTestData ReadSignatureTestData(const base::StringPiece& file_name);
 
-// Reads a file from the test data directory
-// (//src/components/test/data/cast_certificate)
-std::string ReadTestFileToString(const base::StringPiece& file_name);
-
 }  // namespace testing
 
 }  // namespace cast_certificate