WebRTCCertificateGenerator should not use std::string.

third_party/WebKit/public/platform/WebRTCCertificateGenerator.h

 /*
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebRTCCertificateGenerator_h
 #define WebRTCCertificateGenerator_h
 
 #include "public/platform/WebCallbacks.h"
 #include "public/platform/WebRTCCertificate.h"
 #include "public/platform/WebRTCKeyParams.h"
+#include "public/platform/WebString.h"
 
 #include <memory>
 
 namespace blink {
 
 using WebRTCCertificateCallback = WebCallbacks<std::unique_ptr<WebRTCCertificate>, void>;
 
 // Interface defining a class that can generate WebRTCCertificates asynchronously.
 class WebRTCCertificateGenerator {
 public:
     virtual ~WebRTCCertificateGenerator() {}
 
     // Start generating a certificate asynchronously. |observer| is invoked on the
     // same thread that called generateCertificate when the operation is completed.
     virtual void generateCertificate(
         const WebRTCKeyParams&,
         std::unique_ptr<WebRTCCertificateCallback> observer) = 0;
     virtual void generateCertificateWithExpiration(
         const WebRTCKeyParams&,
         uint64_t expiresMs,
         std::unique_ptr<WebRTCCertificateCallback> observer) = 0;
 
     // Determines if the parameters are supported by |generateCertificate|.
     // For example, if the number of bits of some parameter is too small or too large we
     // may want to reject it for security or performance reasons.
     virtual bool isSupportedKeyParams(const WebRTCKeyParams&) = 0;
 
     // Creates a certificate from the PEM strings. See also |WebRTCCertificate::toPEM|.
     virtual std::unique_ptr<WebRTCCertificate> fromPEM(
-        const std::string& pemPrivateKey,
-        const std::string& pemCertificate) = 0;
+        blink::WebString pemPrivateKey,
+        blink::WebString pemCertificate) = 0;
 };
 
 } // namespace blink
 
 #endif // WebRTCCertificateGenerator_h