Check buffer index in shared memory for input audio.

media/audio/audio_parameters.h

Index: media/audio/audio_parameters.h
diff --git a/media/audio/audio_parameters.h b/media/audio/audio_parameters.h
index 3820d8cc3c91de2f3f7168d58074d2b25f8a4072..025f1cd31487d1128b19763668e3828b062920c9 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -5,21 +5,31 @@
 #ifndef MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 #define MEDIA_AUDIO_AUDIO_PARAMETERS_H_
 
+#include <stdint.h>
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/compiler_specific.h"
 #include "base/time/time.h"
+#include "media/base/audio_bus.h"
 #include "media/base/channel_layout.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
-struct MEDIA_EXPORT AudioInputBufferParameters {
+struct ALIGNAS(AudioBus::kChannelAlignment) MEDIA_EXPORT
+    AudioInputBufferParameters {
   double volume;
   uint32 size;
+  uint32_t hardware_delay_bytes;
+  uint32_t id;
   bool key_pressed;
 };
 
+COMPILE_ASSERT(
+    sizeof(AudioInputBufferParameters) % AudioBus::kChannelAlignment == 0,
+           AudioInputBufferParameters_not_aligned);

[tommi (sloooow) - chröme, 2015/08/18 12:44:37]

I think we should apply the alignas attribute on the variable that actually
needs it, which is the 'audio' member variable of AudioInputBuffer.  Then we can
have a compile assert (and I think we use static_assert now), that the offset of
the audio member within AudioInputBuffer, is == kChannelAlignment.

The compiler should inject whatever padding is required before the member
variable, to get that alignment done right.

[Henrik Grunell, 2015/08/19 14:28:38]

Did that and hit dcheck in AudioBus::WrapMemory. As discussing and debugging
offline the problem is we rely on calculating required size by using
sizeof(AudioInputBufferParameters) + size for AudioBus data. This is done in
several places. So sticking with this seems like the best way.

+
 // Use a struct-in-struct approach to ensure that we can calculate the required
 // size as sizeof(AudioInputBufferParameters) + #(bytes in audio buffer) without
 // using packing.