Simplify OriginTrialContext and the way it validates tokens.

content/renderer/origin_trials/web_trial_token_validator_impl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_RENDERER_ORIGIN_TRIALS_WEB_TRIAL_TOKEN_VALIDATOR_IMPL_H_
 #define CONTENT_RENDERER_ORIGIN_TRIALS_WEB_TRIAL_TOKEN_VALIDATOR_IMPL_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/platform/WebTrialTokenValidator.h"
 
 namespace content {
 
 // The TrialTokenValidator is called by the Origin Trials Framework code in
 // Blink to validate tokens to enable experimental features.
 //
 // This class is thread-safe.
 class CONTENT_EXPORT WebTrialTokenValidatorImpl
     : public NON_EXPORTED_BASE(blink::WebTrialTokenValidator) {
  public:
   WebTrialTokenValidatorImpl();
   ~WebTrialTokenValidatorImpl() override;
 
   // blink::WebTrialTokenValidator implementation
   blink::WebOriginTrialTokenStatus validateToken(
       const blink::WebString& token,
       const blink::WebSecurityOrigin& origin,
-      const blink::WebString& featureName) override;
+      blink::WebString* feature_name) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WebTrialTokenValidatorImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_ORIGIN_TRIALS_WEB_TRIAL_TOKEN_VALIDATOR_IMPL_H_