Always wait for DataReady() on Windows WaveOut.

content/browser/renderer_host/media/audio_sync_reader.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 "content/browser/renderer_host/media/audio_sync_reader.h"
 
 #include <algorithm>
 
 #include "base/process_util.h"
 #include "base/shared_memory.h"
-#include "base/threading/platform_thread.h"
 #include "media/audio/audio_buffers_state.h"
 #include "media/audio/audio_parameters.h"
 #include "media/audio/shared_memory_util.h"
 
-#if defined(OS_WIN)
-const int kMinIntervalBetweenReadCallsInMs = 10;
-#endif
-
 using media::AudioBus;
 
 namespace content {
 
 AudioSyncReader::AudioSyncReader(base::SharedMemory* shared_memory,
                                  const media::AudioParameters& params,
                                  int input_channels)
     : shared_memory_(shared_memory),
       input_channels_(input_channels) {
   packet_size_ = media::PacketSizeInBytes(shared_memory_->created_size());
@@ skipping 25 matching lines @@
     // can find out if data became available.
     media::SetUnknownDataSize(shared_memory_, packet_size_);
   }
 
   if (socket_.get()) {
     socket_->Send(&bytes, sizeof(bytes));
   }
 }
 
 int AudioSyncReader::Read(AudioBus* source, AudioBus* dest) {
-#if defined(OS_WIN)
-  // HACK: yield if reader is called too often.
-  // Problem is lack of synchronization between host and renderer. We cannot be
-  // sure if renderer already filled the buffer, and due to all the plugins we
-  // cannot change the API, so we yield if previous call was too recent.
-  // Optimization: if renderer is "new" one that writes length of data we can
-  // stop yielding the moment length is written -- not ideal solution,
-  // but better than nothing.
-  while (!DataReady() &&
-         ((base::Time::Now() - previous_call_time_).InMilliseconds() <
-          kMinIntervalBetweenReadCallsInMs)) {
-    base::PlatformThread::YieldCurrentThread();
-  }
-  previous_call_time_ = base::Time::Now();
-#endif
-
   // Copy optional synchronized live audio input for consumption by renderer
   // process.
   if (source && input_bus_.get()) {
     DCHECK_EQ(source->channels(), input_bus_->channels());
     DCHECK_LE(source->frames(), input_bus_->frames());
     source->CopyTo(input_bus_.get());
   }
 
   // Retrieve the actual number of bytes available from the shared memory.  If
   // the renderer has not completed rendering this value will be invalid (still
@@ skipping 62 matching lines @@
     base::FileDescriptor* foreign_handle) {
   foreign_handle->fd = foreign_socket_->handle();
   foreign_handle->auto_close = false;
   if (foreign_handle->fd != -1)
     return true;
   return false;
 }
 #endif
 
 }  // namespace content