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

media/base/audio_splicer.cc

Index: media/base/audio_splicer.cc
diff --git a/media/base/audio_splicer.cc b/media/base/audio_splicer.cc
index 7fafc8bbbaca976eec83394d05847363c43afba0..0c8ac343324efa8720241e322d42b222318ac7bc 100644
--- a/media/base/audio_splicer.cc
+++ b/media/base/audio_splicer.cc
@@ -302,8 +302,10 @@ bool AudioSplicer::AddInput(const scoped_refptr<AudioBuffer>& input) {
   // 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