Randomly enable leak detector based on probability parameter

chrome/browser/metrics/leak_detector/leak_detector_controller.h

 // Copyright 2016 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_LEAK_DETECTOR_LEAK_DETECTOR_CONTROLLER_H_
 #define CHROME_BROWSER_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 17 matching lines @@
 
   // Retrieves all reports in |stored_reports_|, moving them to |*reports|.
   // |stored_reports_| is empty afterwards.
   void GetLeakReports(std::vector<MemoryLeakReportProto>* reports);
 
  protected:
   // LeakDetector::Observer:
   void OnLeaksFound(const std::vector<MemoryLeakReportProto>& reports) override;
 
   // LeakDetectorRemoteController::LocalController:
-  MemoryLeakReportProto::Params GetParams() const override;
+  MemoryLeakReportProto::Params GetParamsAndRecordRequest() override;
   void SendLeakReports(
       const std::vector<MemoryLeakReportProto>& reports) override;
   void OnRemoteProcessShutdown() override;
 
  private:
+  // Returns true to indicate that LeakDetector should be enabled on a renderer
+  // process. This is determined as follows:
+  // 1. If the number of processes running LeakDetector is not at max, returns
+  //    true with a probability of |per_process_enable_probability_|.
+  // 2. If the number of processes running LeakDetector has reached the max,
+  //    returns false.
+  bool ShouldRandomlyEnableLeakDetectorOnRendererProcess() const;
+
   // Stores a given array of leak reports in |stored_reports_|. |process_type|
   // is the type of process that generated these reports. The reports must all
   // come from the same process type.
   void StoreLeakReports(const std::vector<MemoryLeakReportProto>& reports,
                         MemoryLeakReportProto::ProcessType process_type);
 
   // All leak reports received through OnLeakFound() are stored in protobuf
   // format.
   std::vector<MemoryLeakReportProto> stored_reports_;
 
   // Contains all the parameters passed to LeakDetector. Store them in a single
   // protobuf message instead of in separate member variables.
   const MemoryLeakReportProto::Params params_;
 
   // The build ID of the current Chrome binary.
   std::vector<uint8_t> build_id_;
 
+  // The probability that each process will have the leak detector enabled on
+  // it. For remote processes, this is determined by sending |params_| for
+  // initialization. If the remote process is not to have leak detector enabled,
+  // |params_.sampling_rate()| will be set to 0. Whether or not to enable for a
+  // particular process is independent of the decision for all other processes.
+  double browser_process_enable_probability_;
+  double renderer_process_enable_probability_;
+
+  // The maximum allowed number of renderer processes with leak detector running
+  // simultaneously.
+  int max_renderer_processes_with_leak_detector_enabled_;
+
+  // The number of renderer processes on which the leak detector has been
+  // enabled and is running.
+  int num_renderer_processes_with_leak_detector_enabled_;
+
   // For thread safety.
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(LeakDetectorController);
 };
 
 }  // namespace metrics
 
 #endif  // CHROME_BROWSER_METRICS_LEAK_DETECTOR_LEAK_DETECTOR_CONTROLLER_H_