Added incident report for variations seed signature mismatch.

chrome/browser/metrics/variations/variations_service.h

Index: chrome/browser/metrics/variations/variations_service.h
diff --git a/chrome/browser/metrics/variations/variations_service.h b/chrome/browser/metrics/variations/variations_service.h
index 108d621dbde88993ef1fd273fd7d5a3b7d5c0ce5..8c4d795047c831119312fa1d9588f750a4eb9721 100644
--- a/chrome/browser/metrics/variations/variations_service.h
+++ b/chrome/browser/metrics/variations/variations_service.h
@@ -133,6 +133,10 @@ class VariationsService
     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.