Initialize the shared memory to appease Valgrind.

content/renderer/media/audio_device.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/renderer/media/audio_device.h"
 
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time.h"
@@ skipping 255 matching lines @@
   TRACE_EVENT0("audio", "AudioDevice::FireRenderCallback");
 
   // Update the audio-delay measurement then ask client to render audio.
   size_t num_frames = render_callback_->Render(audio_data_,
       audio_parameters_.frames_per_buffer(), audio_delay_milliseconds);
 
   // Interleave, scale, and clip to int.
   // TODO(crogers/vrk): Figure out a way to avoid the float -> int -> float
   // conversions that happen in the <audio> and WebRTC scenarios.
   media::InterleaveFloatToInt(audio_data_, shared_memory_.memory(),
-      audio_parameters_.frames_per_buffer(),
-      audio_parameters_.bits_per_sample() / 8);
+      num_frames, audio_parameters_.bits_per_sample() / 8);
 
   // Let the host know we are done.
   media::SetActualDataSizeInBytes(&shared_memory_, memory_length_,
       num_frames * audio_parameters_.GetBytesPerFrame());
 }