Added incident report for variations seed signature mismatch.

chrome/browser/metrics/variations/variations_seed_store.h

Index: chrome/browser/metrics/variations/variations_seed_store.h
diff --git a/chrome/browser/metrics/variations/variations_seed_store.h b/chrome/browser/metrics/variations/variations_seed_store.h
index c81b15e3e0967def607055df822dd13cd7ed7371..834bf2521dcabf070bfe02ef1d157b92fc7e1baf 100644
--- a/chrome/browser/metrics/variations/variations_seed_store.h
+++ b/chrome/browser/metrics/variations/variations_seed_store.h
@@ -55,6 +55,11 @@ class VariationsSeedStore {
   // 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 {
@@ -88,6 +93,10 @@ class VariationsSeedStore {
   // 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);
 };