VmCameraMicManager calls ShouldUseCrosCameraService in thread pool

See the bug for details. This also changes the behavior a little bit
--- VmCameraMicManager now will subscribe to cras even if the camera
service is not available.

Fixed: 167491603
Change-Id: I7d6852cfe64badc0b8a791f91f24a3ffff150173
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2598532
Commit-Queue: Jason Lin <lxj@google.com>
Reviewed-by: Joel Hockey <joelhockey@chromium.org>
Cr-Commit-Position: refs/heads/master@{#838802}

chrome/browser/chromeos/camera_mic/vm_camera_mic_manager.cc

@@ -79,6 +79,8 @@ VmCameraMicManager::VmCameraMicManager()
                               base::Unretained(this))) {}
 
 void VmCameraMicManager::OnPrimaryUserSessionStarted(Profile* primary_profile) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
   primary_profile_ = primary_profile;
   crostini_vm_notification_observer_.Initialize(
       primary_profile_, base::BindRepeating(OpenCrostiniSettings));
@@ -90,14 +92,12 @@ void VmCameraMicManager::OnPrimaryUserSessionStarted(Profile* primary_profile) {
   }
 
   // Only do the subscription in real ChromeOS environment.
-  if (base::SysInfo::IsRunningOnChromeOS() &&
-      media::ShouldUseCrosCameraService()) {
-    auto* camera = media::CameraHalDispatcherImpl::GetInstance();
-    // OnActiveClientChange() will be called automatically after the
-    // subscription, so there is no need to get the current status here.
-    camera->AddActiveClientObserver(this);
-    OnCameraPrivacySwitchStatusChanged(
-        camera->AddCameraPrivacySwitchObserver(this));
+  if (base::SysInfo::IsRunningOnChromeOS()) {
+    base::ThreadPool::PostTaskAndReplyWithResult(
+        FROM_HERE, {base::MayBlock()},
+        base::BindOnce(media::ShouldUseCrosCameraService),
+        base::BindOnce(&VmCameraMicManager::MaybeSubscribeToCameraService,
+                       base::Unretained(this)));
 
     CrasAudioHandler::Get()->AddAudioObserver(this);
     // Fetch the current value.
@@ -113,6 +113,22 @@ void VmCameraMicManager::OnPrimaryUserSessionStarted(Profile* primary_profile) {
 // we do not do clean up (e.g. deregister as observers) here.
 VmCameraMicManager::~VmCameraMicManager() = default;
 
+void VmCameraMicManager::MaybeSubscribeToCameraService(
+    bool should_use_cros_camera_service) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  if (!should_use_cros_camera_service) {
+    return;
+  }
+
+  auto* camera = media::CameraHalDispatcherImpl::GetInstance();
+  // OnActiveClientChange() will be called automatically after the
+  // subscription, so there is no need to get the current status here.
+  camera->AddActiveClientObserver(this);
+  OnCameraPrivacySwitchStatusChanged(
+      camera->AddCameraPrivacySwitchObserver(this));
+}
+
 void VmCameraMicManager::UpdateVmInfoAndNotifications(
     VmType vm,
     void (VmInfo::*updator)(bool),

chrome/browser/chromeos/camera_mic/vm_camera_mic_manager.h

@@ -130,6 +130,8 @@ class VmCameraMicManager : public media::CameraActiveClientObserver,
     base::WeakPtrFactory<VmNotificationObserver> weak_ptr_factory_{this};
   };
 
+  void MaybeSubscribeToCameraService(bool should_use_cros_camera_service);
+
   // media::CameraActiveClientObserver
   void OnActiveClientChange(cros::mojom::CameraClientType type,
                             bool is_active) override;