[Mojo Video Capture] Fix VideoCaptureManager exposing implementation details to clients

media/capture/video/video_capture_system.cc

-// Copyright 2017 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 "media/capture/video/video_capture_system.h"
-
-#include "media/base/bind_to_current_loop.h"
-
-namespace {
-
-// Compares two VideoCaptureFormat by checking smallest frame_size area, then
-// by _largest_ frame_rate. Used to order a VideoCaptureFormats vector so that
-// the first entry for a given resolution has the largest frame rate, as needed
-// by the ConsolidateCaptureFormats() method.
-bool IsCaptureFormatSmaller(const media::VideoCaptureFormat& format1,
-                            const media::VideoCaptureFormat& format2) {
-  DCHECK(format1.frame_size.GetCheckedArea().IsValid());
-  DCHECK(format2.frame_size.GetCheckedArea().IsValid());
-  if (format1.frame_size.GetCheckedArea().ValueOrDefault(0) ==
-      format2.frame_size.GetCheckedArea().ValueOrDefault(0)) {
-    return format1.frame_rate > format2.frame_rate;
-  }
-  return format1.frame_size.GetCheckedArea().ValueOrDefault(0) <
-         format2.frame_size.GetCheckedArea().ValueOrDefault(0);
-}
-
-bool IsCaptureFormatSizeEqual(const media::VideoCaptureFormat& format1,
-                              const media::VideoCaptureFormat& format2) {
-  DCHECK(format1.frame_size.GetCheckedArea().IsValid());
-  DCHECK(format2.frame_size.GetCheckedArea().IsValid());
-  return format1.frame_size.GetCheckedArea().ValueOrDefault(0) ==
-         format2.frame_size.GetCheckedArea().ValueOrDefault(0);
-}
-
-// This function receives a list of capture formats, removes duplicated
-// resolutions while keeping the highest frame rate for each, and forcing I420
-// pixel format.
-void ConsolidateCaptureFormats(media::VideoCaptureFormats* formats) {
-  if (formats->empty())
-    return;
-  std::sort(formats->begin(), formats->end(), IsCaptureFormatSmaller);
-  // Due to the ordering imposed, the largest frame_rate is kept while removing
-  // duplicated resolutions.
-  media::VideoCaptureFormats::iterator last =
-      std::unique(formats->begin(), formats->end(), IsCaptureFormatSizeEqual);
-  formats->erase(last, formats->end());
-  // Mark all formats as I420, since this is what the renderer side will get
-  // anyhow: the actual pixel format is decided at the device level.
-  // Don't do this for Y16 format as it is handled separatelly.
-  for (auto& format : *formats) {
-    if (format.pixel_format != media::PIXEL_FORMAT_Y16)
-      format.pixel_format = media::PIXEL_FORMAT_I420;
-  }
-}
-
-}  // anonymous namespace
-
-namespace media {
-
-VideoCaptureSystem::VideoCaptureSystem(
-    std::unique_ptr<VideoCaptureDeviceFactory> factory)
-    : factory_(std::move(factory)) {
-  thread_checker_.DetachFromThread();
-}
-
-VideoCaptureSystem::~VideoCaptureSystem() = default;
-
-void VideoCaptureSystem::GetDeviceInfosAsync(
-    const DeviceInfoCallback& result_callback) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  // Use of Unretained() is safe assuming that |result_callback| has ownership
-  // of |this|.
-  factory_->EnumerateDeviceDescriptors(media::BindToCurrentLoop(
-      base::Bind(&VideoCaptureSystem::OnDescriptorsReceived,
-                 base::Unretained(this), result_callback)));
-}
-
-// Creates a VideoCaptureDevice object. Returns NULL if something goes wrong.
-std::unique_ptr<VideoCaptureDevice> VideoCaptureSystem::CreateDevice(
-    const std::string& device_id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  const VideoCaptureDeviceInfo* device_info = LookupDeviceInfoFromId(device_id);
-  if (!device_info)
-    return nullptr;
-  return factory_->CreateDevice(device_info->descriptor);
-}
-
-void VideoCaptureSystem::OnDescriptorsReceived(
-    const DeviceInfoCallback& result_callback,
-    std::unique_ptr<VideoCaptureDeviceDescriptors> descriptors) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  // For devices for which we already have an entry in |devices_info_cache_|,
-  // we do not want to query the |factory_| for supported formats again. We
-  // simply copy them from |devices_info_cache_|.
-  std::vector<VideoCaptureDeviceInfo> new_devices_info_cache;
-  new_devices_info_cache.reserve(descriptors->size());
-  for (const auto& descriptor : *descriptors) {
-    if (auto* cached_info = LookupDeviceInfoFromId(descriptor.device_id)) {
-      new_devices_info_cache.push_back(*cached_info);
-    } else {
-      // Query for supported formats in order to create the entry.
-      VideoCaptureDeviceInfo device_info(descriptor);
-      factory_->GetSupportedFormats(descriptor, &device_info.supported_formats);
-      ConsolidateCaptureFormats(&device_info.supported_formats);
-      new_devices_info_cache.push_back(device_info);
-    }
-  }
-
-  devices_info_cache_.swap(new_devices_info_cache);
-  result_callback.Run(devices_info_cache_);
-}
-
-const VideoCaptureDeviceInfo* VideoCaptureSystem::LookupDeviceInfoFromId(
-    const std::string& device_id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  auto iter = std::find_if(
-      devices_info_cache_.begin(), devices_info_cache_.end(),
-      [&device_id](const media::VideoCaptureDeviceInfo& device_info) {
-        return device_info.descriptor.device_id == device_id;
-      });
-  if (iter == devices_info_cache_.end())
-    return nullptr;
-  return &(*iter);
-}
-
-}  // namespace media