Pass camera facing to WebKit

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 029b0638c4e3ced5da47532ccb1c32e5b6504b51..14889a8385160a1144f2b0076ba847fef4e2f2fb 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -25,6 +25,7 @@
 #include "base/task_runner_util.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_local.h"
+#include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/renderer_host/media/audio_input_device_manager.h"
@@ -59,6 +60,7 @@
 
 #if defined(OS_CHROMEOS)
 #include "chromeos/audio/cras_audio_handler.h"
+#include "media/capture/video/linux/camera_facing_chromeos.h"
 #endif
 
 namespace content {
@@ -67,6 +69,12 @@ base::LazyInstance<base::ThreadLocalPointer<MediaStreamManager>>::Leaky
     g_media_stream_manager_tls_ptr = LAZY_INSTANCE_INITIALIZER;
 
 namespace {
+
+#if defined(OS_CHROMEOS)
+base::LazyInstance<media::CameraFacingChromeOS>::Leaky g_camera_facing =
+    LAZY_INSTANCE_INITIALIZER;

[hta - Chromium, 2017/01/12 19:36:41]

If this is a singleton, does it make the assumption that a ChromeOS device has
only one camera?

If not, how is a ChromeOS device with two cameras represented?
Remember that ChromeOS devices have USB ports; cameras attached there will have
to have facing = "none".

[shenghao, 2017/01/13 11:09:34]

No.
g_camera_facing is a helper class that takes in model_id and/or usb_id and tell
you what facing the device is. Facing information for each device is stored in
MediaStreamDevice. If one chromebook has 2 cameras, then there will be 2
MediaStreamDevice. I rename g_camera_facing to g_camera_facing_helper to make it
more clear.

For externally plugged in cameras,
g_camera_facing_helper.Get().GetCameraFacing() would return NONE.

+#endif
+
 // Creates a random label used to identify requests.
 std::string RandomLabel() {
   // An earlier PeerConnection spec [1] defined MediaStream::label alphabet as
@@ -207,12 +215,34 @@ MediaDeviceType ConvertToMediaDeviceType(MediaStreamType stream_type) {
   return NUM_MEDIA_DEVICE_TYPES;
 }
 
+VideoFacingMode GetVideoFacing(std::string device_id,
+                               std::string model_id,
+                               MediaStreamType stream_type) {
+#if defined(OS_CHROMEOS)
+  media::CameraFacingChromeOS::LensFacing facing =
+      g_camera_facing.Get().GetCameraFacing(device_id, model_id);
+  switch (facing) {
+    case media::CameraFacingChromeOS::LensFacing::FRONT:
+      return VideoFacingMode::MEDIA_VIDEO_FACING_USER;
+    case media::CameraFacingChromeOS::LensFacing::BACK:
+      return VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT;
+  }
+#endif
+  if (IsScreenCaptureMediaType(stream_type)) {
+    return VideoFacingMode::MEDIA_VIDEO_FACING_ENVIRONMENT;

[hta - Chromium, 2017/01/12 19:36:41]

How does this choice make sense?

I'd have thought not saying anything (ie none) would be more correct.

[shenghao, 2017/01/13 11:09:34]

done

+  }
+  return VideoFacingMode::MEDIA_VIDEO_FACING_NONE;
+}
+
 MediaStreamDevices ConvertToMediaStreamDevices(
     MediaStreamType stream_type,
     const MediaDeviceInfoArray& device_infos) {
+  base::ThreadRestrictions::SetIOAllowed(true);

[jochen (gone - plz use gerrit), 2017/01/12 11:54:41]

why is this required? how long will the operation block? Should this be done on
a background thread?

[shenghao, 2017/01/13 11:09:34]

Because we need to access camera config file when g_camera_facing is created.
Now I moved it to when VideoCaptureDeviceDescriptor is created, so no need to
access IO here anymore.

   MediaStreamDevices devices;
   for (const auto& info : device_infos) {
-    devices.emplace_back(stream_type, info.device_id, info.label);
+    devices.emplace_back(
+        stream_type, info.device_id, info.label,
+        GetVideoFacing(info.device_id, info.model_id, stream_type));
   }
 
   return devices;