Pass camera facing to WebKit

content/browser/renderer_host/media/media_devices_manager.cc

 // Copyright 2016 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_devices_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 367 matching lines @@
                  is_input),
       base::Bind(&MediaDevicesManager::DevicesEnumerated,
                  weak_factory_.GetWeakPtr(), type));
 }
 
 void MediaDevicesManager::VideoInputDevicesEnumerated(
     const media::VideoCaptureDeviceDescriptors& descriptors) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   MediaDeviceInfoArray snapshot;
   for (const auto& descriptor : descriptors) {
-    snapshot.emplace_back(descriptor.device_id, descriptor.GetNameAndModel(),
-                          std::string());
+    snapshot.emplace_back(descriptor);

[miu, 2017/01/05 21:55:33]

nit: push_back() would be more appropriate here.

[shenghao, 2017/01/06 09:43:01]

Why? If using push_back(), I will need to create a temporary MediaDeviceInfo
object and incur one extra copy.

[miu, 2017/01/10 22:14:23]

push_back() takes a const-ref argument (or an rvalue). You are giving it a
const-ref type. std::vector will copy-construct in-place. There is no extra
copy. ;-)

emplace_back() takes arguments to a constructor of the class. So, C++ will take
your const-ref and invoke the copy-constructor in-place. Same thing as
push_back, but the compiler may have to do more work to parse/analyze the
varargs and choose a constructor.

http://en.cppreference.com/w/cpp/container/vector/emplace_back
http://en.cppreference.com/w/cpp/container/vector/push_back

Like I said, a nit point, but since your intention is to insert a copy of an
existing object (as opposed to constructing a different object and inserting
it), push_back() is slightly more appropriate.

[shenghao, 2017/01/11 12:00:53]

Actually, |snapshot| is a vector of MediaDeviceInfo and |descriptor| is a
VideoCaptureDeviceDescriptor, so I am creating the MediaDeviceInfo object
through emplace_back(). ;)

[miu, 2017/01/11 21:08:44]

OIC! Okay then, sounds good to me. :)

   }

[mcasas, 2017/01/05 20:26:37]

No {} for one-line bodies.

[shenghao, 2017/01/06 09:43:01]

Done.

   DevicesEnumerated(MEDIA_DEVICE_TYPE_VIDEO_INPUT, snapshot);
 }
 
 void MediaDevicesManager::DevicesEnumerated(
     MediaDeviceType type,
     const MediaDeviceInfoArray& snapshot) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(IsValidMediaDeviceType(type));
   UpdateSnapshot(type, snapshot);
   cache_infos_[type].UpdateCompleted();
@@ skipping 119 matching lines @@
     const MediaDeviceInfoArray& snapshot) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(IsValidMediaDeviceType(type));
 
   for (const auto& subscriber : device_change_subscribers_[type]) {
     subscriber->OnDevicesChanged(type, snapshot);
   }
 }
 
 }  // namespace content