Added incident report for variations seed signature mismatch.

chrome/browser/metrics/variations/variations_seed_store.h

 // Copyright 2014 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 CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_
 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 37 matching lines @@
   void UpdateSeedDateAndLogDayChange(const base::Time& server_date_fetched);
 
   // Returns the serial number of the last loaded or stored seed.
   const std::string& variations_serial_number() const {
     return variations_serial_number_;
   }
 
   // Registers Local State prefs used by this class.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
+  // If the loaded signature is invalid, returns true and sets
+  // |invalid_signature| to the loaded signature. Otherwise returns false and

[Alexei Svitkine (slow), 2014/10/14 18:15:06]

I would mention that the content of |invalid_signature| is actually the
base64-encoded serialized seed data. (Otherwise it's not clear if it's just the
serialized proto bytes, which are also commonly stored in std::string). Maybe
even rename the param to make that clear - e.g. |invalid_baset64_signature| -
and do it throughout.

[Georges Khalil, 2014/10/15 14:41:47]

Done.

+  // |invalid_signature| is not modified.
+  bool GetInvalidSignature(std::string* invalid_signature) const;
+
  protected:
   // Note: UMA histogram enum - don't re-order or remove entries.
   enum VerifySignatureResult {
     VARIATIONS_SEED_SIGNATURE_MISSING,
     VARIATIONS_SEED_SIGNATURE_DECODE_FAILED,
     VARIATIONS_SEED_SIGNATURE_INVALID_SIGNATURE,
     VARIATIONS_SEED_SIGNATURE_INVALID_SEED,
     VARIATIONS_SEED_SIGNATURE_VALID,
     VARIATIONS_SEED_SIGNATURE_ENUM_SIZE,
   };
@@ skipping 13 matching lines @@
 
   // Clears all prefs related to variations seed storage.
   void ClearPrefs();
 
   // The pref service used to persist the variations seed.
   PrefService* local_state_;
 
   // Cached serial number from the most recently fetched variations seed.
   std::string variations_serial_number_;
 
+  // Keeps track of an invalid signature.
+  bool is_invalid_signature_;
+  std::string invalid_signature_;
+
   DISALLOW_COPY_AND_ASSIGN(VariationsSeedStore);
 };
 
 }  // namespace chrome_variations
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_