Introduce AudioDiscardHelper. Refactor audio decoders to use it.

media/base/test_helpers.cc

 // Copyright (c) 2012 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/base/test_helpers.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/pickle.h"
@@ skipping 167 matching lines @@
   //   start + increment
   //   start + 2 * increment, ...
   // While, values in channel 1 will be:
   //   start + frames * increment
   //   start + (frames + 1) * increment
   //   start + (frames + 2) * increment, ...
   const size_t output_size =
       output->channel_data().size() == 1 ? frames * channels : frames;
   for (size_t ch = 0; ch < output->channel_data().size(); ++ch) {
     T* buffer = reinterpret_cast<T*>(output->channel_data()[ch]);
+    const T v = static_cast<T>(start + ch * output_size * increment);
     for (size_t i = 0; i < output_size; ++i) {
-      buffer[i] = start;
-      start += increment;
+      buffer[i] = static_cast<T>(v + i * increment);
     }
   }
   return output;
 }
 
 // Instantiate all the types of MakeAudioBuffer() and
 // MakeAudioBuffer() needed.
 #define DEFINE_MAKE_AUDIO_BUFFER_INSTANCE(type)              \
   template scoped_refptr<AudioBuffer> MakeAudioBuffer<type>( \
       SampleFormat format,                                   \
@@ skipping 40 matching lines @@
   int width = 0;
   int height = 0;
   bool success = pickle.ReadString(&header) && pickle.ReadInt(&width) &&
                  pickle.ReadInt(&height);
   return (success && header == kFakeVideoBufferHeader &&
           width == config.coded_size().width() &&
           height == config.coded_size().height());
 }
 
 }  // namespace media