Add basic resample support to WASAPIAudioInputStream.

media/base/audio_block_fifo.h

Index: media/base/audio_block_fifo.h
diff --git a/media/base/audio_block_fifo.h b/media/base/audio_block_fifo.h
index a90a3dfe65661a3b089f517703c53d9de6c18f78..8c0d5f5cccdc8f660078c94ef21ce00f8504ba42 100644
--- a/media/base/audio_block_fifo.h
+++ b/media/base/audio_block_fifo.h
@@ -29,6 +29,9 @@ class MEDIA_EXPORT AudioBlockFifo {
   // Push() will crash if the allocated space is insufficient.
   void Push(const void* source, int frames, int bytes_per_sample);
 
+  // Pushes zeroed out frames to the FIFO.
+  void PushSilence(int frames);
+
   // Consumes a block of audio from the FIFO.  Returns an AudioBus which
   // contains the consumed audio data to avoid copying.
   // Consume() will crash if the FIFO does not contain a block of data.
@@ -50,6 +53,11 @@ class MEDIA_EXPORT AudioBlockFifo {
   void IncreaseCapacity(int blocks);
 
  private:
+  // Common implementation for Push() and PushSilence.  if |source| is nullptr,
+  // silence will be pushed. To push silence, set source and bytes_per_sample to
+  // nullptr and 0 respectively.
+  void PushInternal(const void* source, int frames, int bytes_per_sample);
+
   // The actual FIFO is a vector of audio buses.
   ScopedVector<AudioBus> audio_blocks_;