trial_token_unittest: Document how to use or update the public key.

content/common/origin_trials/trial_token_unittest.cc

 // Copyright 2015 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.
 
 #include "content/common/origin_trials/trial_token.h"
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/strings/string_piece.h"
@@ skipping 10 matching lines @@
 
 // This is a sample public key for testing the API. The corresponding private
 // key (use this to generate new samples for this test file) is:
 //
 //  0x83, 0x67, 0xf4, 0xcd, 0x2a, 0x1f, 0x0e, 0x04, 0x0d, 0x43, 0x13,
 //  0x4c, 0x67, 0xc4, 0xf4, 0x28, 0xc9, 0x90, 0x15, 0x02, 0xe2, 0xba,
 //  0xfd, 0xbb, 0xfa, 0xbc, 0x92, 0x76, 0x8a, 0x2c, 0x4b, 0xc7, 0x75,
 //  0x10, 0xac, 0xf9, 0x3a, 0x1c, 0xb8, 0xa9, 0x28, 0x70, 0xd2, 0x9a,
 //  0xd0, 0x0b, 0x59, 0xe1, 0xac, 0x2b, 0xb7, 0xd5, 0xca, 0x1f, 0x64,
 //  0x90, 0x08, 0x8e, 0xa8, 0xe0, 0x56, 0x3a, 0x04, 0xd0
+//
+//  This private key can also be found in tools/origin_trials/eftest.key in
+//  binary form. Please update that if changing the key.
+//
+//  To use this with a real browser, use --origin-trial-public-key with the
+//  public key, base-64-encoded:
+//  --origin-trial-public-key=dRCs+TocuKkocNKa0AtZ4awrt9XKH2SQCI6o4FY6BNA=
 const uint8_t kTestPublicKey[] = {
     0x75, 0x10, 0xac, 0xf9, 0x3a, 0x1c, 0xb8, 0xa9, 0x28, 0x70, 0xd2,
     0x9a, 0xd0, 0x0b, 0x59, 0xe1, 0xac, 0x2b, 0xb7, 0xd5, 0xca, 0x1f,
     0x64, 0x90, 0x08, 0x8e, 0xa8, 0xe0, 0x56, 0x3a, 0x04, 0xd0,
 };
 
 // This is a valid, but incorrect, public key for testing signatures against.
 // The corresponding private key is:
 //
 //  0x21, 0xee, 0xfa, 0x81, 0x6a, 0xff, 0xdf, 0xb8, 0xc1, 0xdd, 0x75,
@@ skipping 278 matching lines @@
 
 TEST_F(TrialTokenTest, ExtractMalformedToken) {
   blink::WebOriginTrialTokenStatus status;
   std::unique_ptr<TrialToken> token =
       TrialToken::From(kIncorrectLengthToken, correct_public_key(), &status);
   EXPECT_FALSE(token);
   EXPECT_EQ(blink::WebOriginTrialTokenStatus::Malformed, status);
 }
 
 }  // namespace content