Fix the aec dump crash when users disable aec dump without closing the "Save File" overlay.

content/renderer/media/webrtc_audio_device_impl.cc

 // Copyright 2013 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 "content/renderer/media/webrtc_audio_device_impl.h"
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
 #include "base/win/windows_version.h"
@@ skipping 506 matching lines @@
   if (capturers_.empty() || capturers_.size() > 1)
     return false;
 
   return GetDefaultCapturer()->GetPairedOutputParameters(
       session_id, output_sample_rate, output_frames_per_buffer);
 }
 
 void WebRtcAudioDeviceImpl::EnableAecDump(base::File aec_dump_file) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(aec_dump_file.IsValid());
-  DCHECK(!aec_dump_file_.IsValid());
+
+  // Close the previous AEC dump file description if it has not been consumed.
+  // This can happen if no getUserMedia has been made yet.
+  // TODO(xians): DCHECK(!aec_dump_file_.IsValid()) after the browser
+  // guarantees it won't call EnableAecDump() more than once in a row.
+  if (aec_dump_file_.IsValid())
+    aec_dump_file_.Close();
+
   aec_dump_file_ = aec_dump_file.Pass();
   MaybeStartAecDump();
 }
 
 void WebRtcAudioDeviceImpl::DisableAecDump() {
   DCHECK(thread_checker_.CalledOnValidThread());
   // Simply invalidate the |aec_dump_file_| if we have not pass the ownership
   // to WebRtc.
   if (aec_dump_file_.IsValid()) {
     aec_dump_file_.Close();
@@ skipping 14 matching lines @@
 
   // Start the Aec dump on the current default capturer.
   scoped_refptr<WebRtcAudioCapturer> default_capturer(GetDefaultCapturer());
   if (!default_capturer)
     return;
 
   default_capturer->StartAecDump(aec_dump_file_.Pass());
 }
 
 }  // namespace content