Fix the unnecessary sleep when no back to back OnData call.

media/audio/pulse/pulse_input.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/audio/pulse/pulse_input.h"
 
 #include <pulse/pulseaudio.h>
 
 #include "base/logging.h"
 #include "media/audio/pulse/audio_manager_pulse.h"
@@ skipping 263 matching lines @@
     pa_stream_drop(handle_);
   } while (pa_stream_readable_size(handle_) > 0);
 
   while (fifo_.available_blocks()) {
     const AudioBus* audio_bus = fifo_.Consume();
 
     // Compensate the audio delay caused by the FIFO.
     hardware_delay += fifo_.GetAvailableFrames() * params_.GetBytesPerFrame();
     callback_->OnData(this, audio_bus, hardware_delay, normalized_volume);
 
-    base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(5));
+    // Sleep 5ms to wait until render consumes the data in order to avoid
+    // back to back OnData() method.
+    if (fifo_.available_blocks())
+      base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(5));
   }
 
   pa_threaded_mainloop_signal(pa_mainloop_, 0);
 }
 
 }  // namespace media