Create a mechanism for reporting rappor metrics from non-UMA

components/rappor/rappor_parameters.h

Index: components/rappor/rappor_parameters.h
diff --git a/components/rappor/rappor_parameters.h b/components/rappor/rappor_parameters.h
index ca625ba4d8e3216969d5efe2b545aabb91878029..7f04bd0a316cb0606040a44607b42f6088650d0d 100644
--- a/components/rappor/rappor_parameters.h
+++ b/components/rappor/rappor_parameters.h
@@ -43,6 +43,10 @@ struct RapporParameters {
   Probability one_coin_prob;
   // The probability that a zero bit in the redacted data reports as one.
   Probability zero_coin_prob;
+
+  // When true, this metric will be reported even when most rappor metric
+  // reporting is disabled.
+  bool always_enabled;
 };
 
 }  // namespace rappor