Fix "unreachable code" warnings (MSVC warning 4702) in content/.

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/platform_file.h"
 #include "base/strings/string_util.h"
@@ skipping 444 matching lines @@
   DCHECK(capturer.get());
   base::AutoLock auto_lock(lock_);
   capturers_.remove(capturer);
 }
 
 scoped_refptr<WebRtcAudioCapturer>
 WebRtcAudioDeviceImpl::GetDefaultCapturer() const {
   base::AutoLock auto_lock(lock_);
   // Use the last |capturer| which is from the latest getUserMedia call as
   // the default capture device.
-  for (CapturerList::const_reverse_iterator iter = capturers_.rbegin();
-       iter != capturers_.rend(); ++iter) {
-    return *iter;
-  }
-
-  return NULL;
+  return capturers_.empty() ? NULL : capturers_.back();
 }
 
 void WebRtcAudioDeviceImpl::AddPlayoutSink(
     WebRtcPlayoutDataSource::Sink* sink) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(sink);
   base::AutoLock auto_lock(lock_);
   DCHECK(std::find(playout_sinks_.begin(), playout_sinks_.end(), sink) ==
       playout_sinks_.end());
   playout_sinks_.push_back(sink);
@@ skipping 58 matching lines @@
     return;
 
   default_capturer->StartAecDump(aec_dump_file_);
 
   // Invalidate the |aec_dump_file_| since the ownership of the file has been
   // passed to WebRtc.
   aec_dump_file_ = base::kInvalidPlatformFileValue;
 }
 
 }  // namespace content