PerfProvider: Get collection parameters from Finch

chrome/browser/metrics/perf/random_selector.h

 // Copyright 2015 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_PERF_RANDOM_SELECTOR_H_
 #define CHROME_BROWSER_METRICS_PERF_RANDOM_SELECTOR_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 17 matching lines @@
 //
 // The above line should return "a" with a probability of 50%,
 // "b" with a probability of 40%, and "c" with a probability of 10%:
 class RandomSelector {
  public:
   struct WeightAndValue {
     WeightAndValue(double weight, const std::string& value)
       : weight(weight), value(value) {
     }
 
+    bool operator==(const WeightAndValue& other) const {
+      return weight == other.weight && value == other.value;
+    }
+
     // Probability weight for selecting this value.
     double weight;
     // Value to be returned by Select(), if selected.
     std::string value;
   };
 
   RandomSelector();
   virtual ~RandomSelector();
 
-  // Set the probabilities for various strings.
-  void SetOdds(const std::vector<WeightAndValue>& odds);
+  // Set the probabilities for various strings. Returns false and doesn't
+  // modify the values if odds contains any invalid weights (<=0.0) or if
+  // odds is empty.
+  bool SetOdds(const std::vector<WeightAndValue>& odds);
 
   // Randomly select one of the values from the set.
   const std::string& Select();
 
   // Returns the number of string entries.
   size_t num_values() const {
     return odds_.size();
   }
 
-  // Sum of the |weight| fields in the vector.
+  const std::vector<WeightAndValue>& odds() const { return odds_; }
+
+  // Sum of the |weight| fields in the vector. Returns -1.0 if odds contains any
+  // weight <= 0.0.
   static double SumWeights(const std::vector<WeightAndValue>& odds);
 
  private:
   // Get a floating point number between 0.0 and |max|.
   virtual double RandDoubleUpTo(double max);
 
   // Get a string corresponding to |random| that is in the odds vector.
   // |random| must be a number between zero and the sum of the probability
   // weights.
   const std::string& GetValueFor(double random);
 
   // A dictionary representing the strings to choose from and associated odds.
   std::vector<WeightAndValue> odds_;
 
   // Sum of the probability weights.
   double sum_of_weights_;
 
   DISALLOW_COPY_AND_ASSIGN(RandomSelector);
 };
 
+::std::ostream& operator<<(
+    ::std::ostream& os, const RandomSelector::WeightAndValue& value);
+
 #endif  // CHROME_BROWSER_METRICS_PERF_RANDOM_SELECTOR_H_