Added DCHECK() to prevent NULL-pointer dereference

media/audio/win/wavein_input_win.cc

Index: media/audio/win/wavein_input_win.cc
diff --git a/media/audio/win/wavein_input_win.cc b/media/audio/win/wavein_input_win.cc
index 7eb778d061c927198283c03ad0ff33e9c9fff712..e9a310d480d391e7d512111181ab597ff32c001e 100644
--- a/media/audio/win/wavein_input_win.cc
+++ b/media/audio/win/wavein_input_win.cc
@@ -98,6 +98,7 @@ void PCMWaveInAudioInputStream::SetupBuffers() {
     last = buffer_;
     ::waveInPrepareHeader(wavein_, buffer_, sizeof(WAVEHDR));
   }
+  DCHECK(first);

[Tyler Breisacher (Chromium), 2012/07/25 21:18:15]

This can only be NULL if num_buffers_ is 0, I think. Let's make sure that it's
impossible for num_buffers_ to be 0 rather than just adding a DCHECK?

[Kyle Horimoto, 2012/07/25 21:56:40]

num_buffers_ is only assigned to within the constructor. Thus, we can't be sure
what its value is.

   // Fix the first buffer to point to the last one.
   first->dwUser = reinterpret_cast<DWORD_PTR>(last);
 }