Tighten up media::DecoderBuffer API contract for end of stream buffers.

media/base/data_buffer.h

Index: media/base/data_buffer.h
diff --git a/media/base/data_buffer.h b/media/base/data_buffer.h
index 76215c8beb66042921cbdd2b8971ce935a5f726c..5c02dd6a5a21c07e33d5f558e8ec1da2740fde78 100644
--- a/media/base/data_buffer.h
+++ b/media/base/data_buffer.h
@@ -17,6 +17,8 @@ namespace media {
 //
 // Unlike DecoderBuffer, allocations are assumed to be allocated with the
 // default memory allocator (i.e., new uint8[]).
+//
+// NOTE: It is illegal to call any method when IsEndOfStream() is true.
 class MEDIA_EXPORT DataBuffer : public base::RefCountedThreadSafe<DataBuffer> {
  public:
   // Allocates buffer of size |buffer_size| >= 0.