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

BUG=378713
TEST=manual test:
1Launch chrome and navigate to chrome://webrtc-internals/. 
2.Expand "Create Dump" option >> Check the checkbox option of "enable Diagnostic audio recordings". 
3.With "Save File" overlay opened, again uncheck the same checkbox.

Review URL: https://codereview.chromium.org/310463002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@274523 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/media/webrtc_internals.cc

@@ -246,6 +246,10 @@ void WebRTCInternals::EnableAecDump(content::WebContents* web_contents) {
 void WebRTCInternals::DisableAecDump() {
 #if defined(ENABLE_WEBRTC)
   aec_dump_enabled_ = false;
+
+  // Tear down the dialog since the user has unchecked the AEC dump box.
+  select_file_dialog_ = NULL;
+
   for (RenderProcessHost::iterator i(
            content::RenderProcessHost::AllHostsIterator());
        !i.IsAtEnd(); i.Advance()) {

content/renderer/media/webrtc/peer_connection_dependency_factory.cc

@@ -643,7 +643,9 @@ void PeerConnectionDependencyFactory::OnAecDumpFile(
 
 void PeerConnectionDependencyFactory::OnDisableAecDump() {
   if (MediaStreamAudioProcessor::IsAudioTrackProcessingEnabled()) {
-    GetWebRtcAudioDevice()->DisableAecDump();
+    // Do nothing if OnAecDumpFile() has never been called.
+    if (GetWebRtcAudioDevice())
+      GetWebRtcAudioDevice()->DisableAecDump();
     return;
   }
 

content/renderer/media/webrtc_audio_device_impl.cc

@@ -524,7 +524,14 @@ bool WebRtcAudioDeviceImpl::GetAuthorizedDeviceInfoForAudioRenderer(
 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();
 }