[2/4]Allow hotplugging of primary DRM device

ui/ozone/platform/drm/gpu/drm_device.cc

Index: ui/ozone/platform/drm/gpu/drm_device.cc
diff --git a/ui/ozone/platform/drm/gpu/drm_device.cc b/ui/ozone/platform/drm/gpu/drm_device.cc
index 4d2bcbfe9894496e5c73d91c8282691f8d15d898..fe95a622ca04eb01255310bb612255d75a3a831e 100644
--- a/ui/ozone/platform/drm/gpu/drm_device.cc
+++ b/ui/ozone/platform/drm/gpu/drm_device.cc
@@ -100,14 +100,6 @@ bool CanQueryForResources(int fd) {
   return !drmIoctl(fd, DRM_IOCTL_MODE_GETRESOURCES, &resources);
 }
 
-bool Authenticate(int fd) {
-  drm_magic_t magic;
-  memset(&magic, 0, sizeof(magic));
-  // We need to make sure the DRM device has enough privilege. Use the DRM
-  // authentication logic to figure out if the device has enough permissions.
-  return !drmGetMagic(fd, &magic) && !drmAuthMagic(fd, magic);
-}
-
 }  // namespace
 
 class DrmDevice::IOWatcher
@@ -212,28 +204,6 @@ bool DrmDevice::Initialize() {
     return false;
   }
 
-  bool print_warning = true;
-  // TODO(dnicoara) Ugly hack to block until getting master. This is needed
-  // since DRM devices from an old GPU process may be getting deallocated while
-  // the new GPU process tries to take them.
-  // Move ownership of devices in the Browser process and just have the GPU
-  // processes authenticate.
-  while (!Authenticate(file_.GetPlatformFile())) {
-    PLOG_IF(WARNING, print_warning) << "Failed to take master on "
-                                    << device_path_.value();
-    print_warning = false;
-
-    usleep(100000);
-    file_ =
-        base::File(device_path_, base::File::FLAG_OPEN | base::File::FLAG_READ |
-                                     base::File::FLAG_WRITE);
-    LOG_IF(FATAL, !file_.IsValid())
-        << "Failed to open '" << device_path_.value()
-        << "': " << base::File::ErrorToString(file_.error_details());
-  }
-
-  VLOG(1) << "Succeeded in taking master on " << device_path_.value();
-
 #if defined(USE_DRM_ATOMIC)
   plane_manager_.reset(new HardwareDisplayPlaneManagerAtomic());
 #else