Enforce non-negative BitstreamBuffer id

content/common/gpu/media/video_decode_accelerator_unittest.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.
 //
 // The bulk of this file is support code; sorry about that.  Here's an overview
 // to hopefully help readers of this code:
 // - RenderingHelper is charged with interacting with X11/{EGL/GLES2,GLX/GL} or
 //   Win/EGL.
 // - ClientState is an enum for the state of the decode client used by the test.
 // - ClientStateNotification is a barrier abstraction that allows the test code
@@ skipping 585 matching lines @@
   size_t next_fragment_size = next_fragment_bytes.size();
 
   // Populate the shared memory buffer w/ the fragments, duplicate its handle,
   // and hand it off to the decoder.
   base::SharedMemory shm;
   CHECK(shm.CreateAndMapAnonymous(next_fragment_size));
   memcpy(shm.memory(), next_fragment_bytes.data(), next_fragment_size);
   base::SharedMemoryHandle dup_handle;
   CHECK(shm.ShareToProcess(base::Process::Current().handle(), &dup_handle));
   media::BitstreamBuffer bitstream_buffer(
-      next_bitstream_buffer_id_++, dup_handle, next_fragment_size);
+      next_bitstream_buffer_id_, dup_handle, next_fragment_size);
+  next_bitstream_buffer_id_ = (next_bitstream_buffer_id_ + 1) & 0x7FFFFFFF;

[Ami GONE FROM CHROMIUM, 2013/01/10 23:13:56]

This is kind of silly (since this is a unittest with controlled inputs) but to
be pedantic: your change relies on wrap-around overflow behavior (n_b_b_i_ is an
int) which is not what the standard gives you.
You could make n_b_b_i_ int64 (like GVD) or uint32 to make this snippet correct.

[sheu, 2013/01/10 23:34:48]

Fine.  :-)

   decoder_->Decode(bitstream_buffer);
   ++outstanding_decodes_;
   encoded_data_next_pos_to_decode_ = end_pos;
 
   if (!remaining_play_throughs_ &&
       -delete_decoder_state_ == next_bitstream_buffer_id_) {
     DeleteDecoder();
   }
 }
 
@@ skipping 318 matching lines @@
                  base::Unretained(&event)));
   event.Wait();
 #elif defined(OS_CHROMEOS) && defined(ARCH_CPU_ARMEL)
   content::OmxVideoDecodeAccelerator::PreSandboxInitialization();
 #elif defined(OS_CHROMEOS) && defined(ARCH_CPU_X86_FAMILY)
   content::VaapiVideoDecodeAccelerator::PreSandboxInitialization();
 #endif
 
   return RUN_ALL_TESTS();
 }