Add unit tests for sub-components of CaptureScheduler.

remoting/base/running_average.h

 // Copyright (c) 2011 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.
 
-// RunningAverage defined in this file is used to generate statistics for
-// bandwidth, latency and other performance metrics for remoting. Usually
-// this data comes in as a stream and fluctuates a lot. They are processed by
-// this class to generate a more stable value by taking average within a
-// window of data points.
-
-// All classes defined are thread-safe.
-
 #ifndef REMOTING_BASE_RUNNING_AVERAGE_H_
 #define REMOTING_BASE_RUNNING_AVERAGE_H_
 
 #include <deque>
 
 #include "base/basictypes.h"
-#include "base/synchronization/lock.h"
+#include "base/threading/non_thread_safe.h"
 
 namespace remoting {
 
-class RunningAverage {
+// Calculates the average of the most recent N recorded samples.
+// This is typically used to smooth out random variation in point samples
+// over bandwidth, frame rate, etc.
+class RunningAverage : public base::NonThreadSafe {
  public:
-  // Construct a running average counter for a specific window size. The
-  // |windows_size| most recent values are kept and the average is reported.
+  // Constructs a helper to average over the |window_size| most recent samples.
   explicit RunningAverage(int window_size);
-
   virtual ~RunningAverage();
 
-  // Record the provided data point.
+  // Records a point sample.
   void Record(int64 value);
 
-  // Return the average of data points in the last window.
-  double Average();
+  // Returns the average over up to |window_size| of the most recent samples.
+  double Average() const;
 
  private:
-  // Size of the window. This is of type size_t to avoid casting when comparing
+  // Stores the desired window size, as size_t to avoid casting when comparing
   // with the size of |data_points_|.
-  size_t window_size_;
+  const size_t window_size_;
 
-  // Protects |data_points_| and |sum_|.
-  base::Lock lock_;
-
-  // Keep the values of all the data points.
+  // Stores the |window_size| most recently recorded samples.
   std::deque<int64> data_points_;
 
-  // Sum of values in |data_points_|.
+  // Holds the sum of the samples in |data_points_|.
   int64 sum_;
 
   DISALLOW_COPY_AND_ASSIGN(RunningAverage);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_BASE_RUNNING_AVERAGE_H_