Implement value printer to prevent Valgrind errors in AudioPowerMonitor unit tests.

media/audio/audio_power_monitor_unittest.cc

 // Copyright 2013 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.
 
 #include "media/audio/audio_power_monitor.h"
 
 #include <limits>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 64 matching lines @@
                sizeof(float) * num_to_copy);
       }
     }
   }
 
   float expected_power_;
   bool expected_clipped_;
   scoped_ptr<AudioBus> bus_;
 };
 
+// Value printer for TestScenario.  Required to prevent Valgrind "access to
+// uninitialized memory" errors (http://crbug.com/263315).
+::std::ostream& operator<<(::std::ostream& os, const TestScenario& ts) {
+  return os << "{" << ts.data().channels() << "-channel signal} --> {"
+            << ts.expected_power() << " dBFS, "
+            << (ts.expected_clipped() ? "clipped" : "not clipped")
+            << "}";
+}
+
 // An observer that receives power measurements.  Each power measurement should
 // should make progress towards the goal value.
 class MeasurementObserver {
  public:
   MeasurementObserver(float goal_power_measurement, bool goal_clipped)
       : goal_power_measurement_(goal_power_measurement),
         goal_clipped_(goal_clipped), measurement_count_(0),
         last_power_measurement_(AudioPowerMonitor::zero_power()),
         last_clipped_(false) {}
 
@@ skipping 206 matching lines @@
              WithABadSample(std::numeric_limits<float>::quiet_NaN()),
          TestScenario(kStereoSilentNoise, 2, 2, -46, false),
          TestScenario(kStereoMaxAmplitude, 2, 2,
                       AudioPowerMonitor::max_power(), false),
          TestScenario(kRightChannelMaxAmplitude, 2, 4, -3, false),
          TestScenario(kLeftChannelHalfMaxAmplitude, 2, 4, -9, false),
          TestScenario(kStereoMixed, 2, 4, -2, false),
          TestScenario(kStereoMixed2, 2, 8, -3, false)));
 
 }  // namespace media