Fix a teardown hang caused by an Abort() call while there is a pending read.

media/base/pipeline_impl.cc

Index: media/base/pipeline_impl.cc
diff --git a/media/base/pipeline_impl.cc b/media/base/pipeline_impl.cc
index d039664d27604b9c0a532793513e16a082954e44..e096b2236d2502e3c807971835c5c43151a2eba7 100644
--- a/media/base/pipeline_impl.cc
+++ b/media/base/pipeline_impl.cc
@@ -377,7 +377,9 @@ PipelineImpl::State PipelineImpl::FindNextState(State current) {
   } else if (current == kFlushing) {
     // We will always honor Seek() before Stop(). This is based on the
     // assumption that we never accept Seek() after Stop().
-    DCHECK(IsPipelineSeeking() || IsPipelineStopPending());
+    DCHECK(IsPipelineSeeking() ||
+           IsPipelineStopPending() ||
+           IsPipelineTearingDown());
     return IsPipelineSeeking() ? kSeeking : kStopping;
   } else if (current == kSeeking) {
     return kStarting;