Don't crash when splices are in the past due to bad media.

media/base/audio_splicer.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.
 
 #include "media/base/audio_splicer.h"
 
 #include <cstdlib>
 #include <deque>
 
 #include "base/logging.h"
@@ skipping 284 matching lines @@
   // Ensure |output_sanitizer_| has a valid base timestamp so we can use it for
   // timestamp calculations.
   if (output_ts_helper.base_timestamp() == kNoTimestamp()) {
     output_sanitizer_->ResetTimestampState(
         0, pre_splice_sanitizer_->timestamp_helper().base_timestamp());
   }
 
   // If a splice frame was incorrectly marked due to poor demuxed timestamps, we
   // may not actually have a splice.  Here we check if any frames exist before
   // the splice.  In this case, just transfer all data to the output sanitizer.
-  if (pre_splice_sanitizer_->GetFrameCount() <=

[wolenetz, 2014/08/05 01:00:28]

I'm trying to grok which part of this condition previously led to the CHECK, but
doesn't in your patch set. What were the previous values of r
pre_splice_sanitizer_->GetFrameCount() and
output_ts_helper.GetFramesToTarget(splice_timestamp_) that led to the CHECK?

[DaleCurtis, 2014/08/05 01:03:10]

If frames_before_splice is negative this condition will never be true since
GetFrameCount() > 0.  See the other incorrect splice test cases in the unittest
for context on the rest of this condition.

[wolenetz, 2014/08/07 23:12:12]

Acknowledged.

-      output_ts_helper.GetFramesToTarget(splice_timestamp_)) {
+  const int frames_before_splice =
+      output_ts_helper.GetFramesToTarget(splice_timestamp_);
+  if (frames_before_splice < 0 ||
+      pre_splice_sanitizer_->GetFrameCount() <= frames_before_splice) {
     CHECK(pre_splice_sanitizer_->DrainInto(output_sanitizer_.get()));
 
     // If the file contains incorrectly muxed timestamps, there may be huge gaps
     // between the demuxed and decoded timestamps.
     if (!post_splice_sanitizer_->DrainInto(output_sanitizer_.get()))
       return false;
 
     reset_splice_timestamps();
     return true;
   }
@@ skipping 181 matching lines @@
     AccurateTrimStart(frames_to_trim, remainder, output_ts_helper);
     CHECK(output_sanitizer_->AddInput(remainder));
   }
 
   // Transfer all remaining buffers out and reset once empty.
   CHECK(post_splice_sanitizer_->DrainInto(output_sanitizer_.get()));
   post_splice_sanitizer_->Reset();
 }
 
 }  // namespace media