Move the device enumerate/open/close work to device thread from IO thread

content/browser/renderer_host/media/media_stream_device_settings.cc

 // Copyright (c) 2012 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/browser/renderer_host/media/media_stream_device_settings.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 119 matching lines @@
   host->GetDelegate()->RequestMediaAccessPermission(&request, callback);
 }
 
 }  // namespace
 
 MediaStreamDeviceSettings::MediaStreamDeviceSettings(
     SettingsRequester* requester)
     : requester_(requester),
       use_fake_ui_(false) {
   DCHECK(requester_);
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 }
 
 MediaStreamDeviceSettings::~MediaStreamDeviceSettings() {
   STLDeleteValues(&requests_);
 }
 
 void MediaStreamDeviceSettings::RequestCaptureDeviceUsage(
     const std::string& label, int render_process_id, int render_view_id,
     const StreamOptions& request_options, const GURL& security_origin) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
@@ skipping 215 matching lines @@
   content::MediaResponseCallback callback =
       base::Bind(&ResponseCallbackHelper::PostResponse,
                  helper.get(), label);
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
       base::Bind(&DoDeviceRequest, *request, callback));
 }
 
 }  // namespace media_stream