Revert of Remove AudioBuffer::set_duration(), instead base on frames.

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 9fae4175f032408eb94e3a5be3ed810972a790c4..b83765e76066bda8e93840f703371959344a6524 100644
--- a/media/base/audio_splicer.cc
+++ b/media/base/audio_splicer.cc
@@ -35,6 +35,20 @@
                               const AudioTimestampHelper& timestamp_helper) {
   buffer->TrimStart(frames_to_trim);
   buffer->set_timestamp(timestamp_helper.GetTimestamp());
+  buffer->set_duration(
+      timestamp_helper.GetFrameDuration(buffer->frame_count()));
+}
+
+// AudioBuffer::TrimEnd() is not as accurate as the timestamp helper, so
+// manually adjust the duration after trimming.
+static void AccurateTrimEnd(int frames_to_trim,
+                            const scoped_refptr<AudioBuffer> buffer,
+                            const AudioTimestampHelper& timestamp_helper) {
+  DCHECK_LT(std::abs(timestamp_helper.GetFramesToTarget(buffer->timestamp())),
+            kMinGapSize);
+  buffer->TrimEnd(frames_to_trim);
+  buffer->set_duration(
+      timestamp_helper.GetFrameDuration(buffer->frame_count()));
 }
 
 // Returns an AudioBus whose frame buffer is backed by the provided AudioBuffer.
@@ -163,12 +177,13 @@
 
     // Create a buffer with enough silence samples to fill the gap and
     // add it to the output buffer.
-    scoped_refptr<AudioBuffer> gap =
-        AudioBuffer::CreateEmptyBuffer(input->channel_layout(),
-                                       input->channel_count(),
-                                       input->sample_rate(),
-                                       frames_to_fill,
-                                       expected_timestamp);
+    scoped_refptr<AudioBuffer> gap = AudioBuffer::CreateEmptyBuffer(
+        input->channel_layout(),
+        input->channel_count(),
+        input->sample_rate(),
+        frames_to_fill,
+        expected_timestamp,
+        output_timestamp_helper_.GetFrameDuration(frames_to_fill));
     AddOutputBuffer(gap);
 
     // Add the input buffer now that the gap has been filled.
@@ -428,7 +443,9 @@
     // If only part of the buffer was consumed, trim it appropriately and stick
     // it into the output queue.
     if (frames_before_splice) {
-      preroll->TrimEnd(preroll->frame_count() - frames_before_splice);
+      AccurateTrimEnd(preroll->frame_count() - frames_before_splice,
+                      preroll,
+                      output_ts_helper);
       CHECK(output_sanitizer_->AddInput(preroll));
       frames_before_splice = 0;
     }
@@ -449,6 +466,8 @@
   const AudioTimestampHelper& output_ts_helper =
       output_sanitizer_->timestamp_helper();
   crossfade_buffer->set_timestamp(output_ts_helper.GetTimestamp());
+  crossfade_buffer->set_duration(
+      output_ts_helper.GetFrameDuration(pre_splice_bus->frames()));
 
   // AudioBuffer::ReadFrames() only allows output into an AudioBus, so wrap
   // our AudioBuffer in one so we can avoid extra data copies.