Revert 112147 - Did not get LGTM from all reviewers.

media/audio/audio_util.cc

 // 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.
 
 // Software adjust volume of samples, allows each audio stream its own
 // volume without impacting master volume for chrome and other applications.
 
 // Implemented as templates to allow 8, 16 and 32 bit implementations.
 // 8 bit is unsigned and biased by 128.
 
@@ skipping 275 matching lines @@
   // The sizes here were determined by experimentation and are roughly
   // the lowest value (for low latency) that still allowed glitch-free
   // audio under high loads.
   //
   // For Mac OS X and Windows the chromium audio backend uses a low-latency
   // Core Audio API, so a low buffer size is possible. For Linux, further
   // tuning may be needed.
 #if defined(OS_MACOSX)
   return 128;
 #elif defined(OS_WIN)
-  if (base::win::GetVersion() <= base::win::VERSION_XP) {
-    // Fall back to Windows Wave implementation on Windows XP or lower
-    // and assume 48kHz as default sample rate.
-    return 2048;
-  }
   // This call must be done on a COM thread configured as MTA.
   // TODO(tommi): http://code.google.com/p/chromium/issues/detail?id=103835.
   int mixing_sample_rate =
       static_cast<int>(WASAPIAudioOutputStream::HardwareSampleRate(eConsole));
   if (mixing_sample_rate == 48000)
     return 480;
   else if (mixing_sample_rate == 44100)
     return 448;
   else
     return 960;
@@ skipping 46 matching lines @@
   char* ptr = static_cast<char*>(shared_memory->memory()) + shared_memory_size;
   DCHECK_EQ(0u, reinterpret_cast<size_t>(ptr) & 3);
 
   // Actual data size stored at the end of the buffer.
   uint32 actual_data_size =
       base::subtle::Acquire_Load(reinterpret_cast<volatile Atomic32*>(ptr));
   return actual_data_size == kUnknownDataSize;
 }
 
 }  // namespace media