Added incident report for variations seed signature mismatch.

chrome/browser/metrics/variations/variations_service.h

 // Copyright (c) 2012 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_SERVICE_H_
 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 115 matching lines @@
       PrefService* local_state,
       metrics::MetricsStateManager* state_manager);
 
   // Set the PrefService responsible for getting policy-related preferences,
   // such as the restrict parameter.
   void set_policy_pref_service(PrefService* service) {
     DCHECK(service);
     policy_pref_service_ = service;
   }
 
+  // Returns true if the variations seed signature is invalid, in which case
+  // it also sets invalid_signature to that value.
+  bool IsVariationsSeedSignatureInvalid(std::string* invalid_signature) const;

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

Would it also make sense to log the seed signature, in addition to the seed?

That way, we could maybe detect which cases are from e.g. just a bit-flip in the
signature, vs. tampering.

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

It could be interesting eventually. For now, we'll only log the signature.

+
  protected:
   // Starts the fetching process once, where |OnURLFetchComplete| is called with
   // the response.
   virtual void DoActualFetch();
 
   // Stores the seed to prefs. Set as virtual and protected so that it can be
   // overridden by tests.
   virtual void StoreSeed(const std::string& seed_data,
                          const std::string& seed_signature,
                          const base::Time& date_fetched);
@@ skipping 84 matching lines @@
 #endif
 
   base::WeakPtrFactory<VariationsService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VariationsService);
 };
 
 }  // namespace chrome_variations
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SERVICE_H_