ozone: Switch some DRM-related warnings to VLOG(1).

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

 // Copyright 2015 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 "ui/ozone/platform/drm/gpu/drm_device_manager.h"
 
 #include <utility>
 
 #include "base/file_descriptor_posix.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 32 matching lines @@
   auto it =
       std::find_if(devices_.begin(), devices_.end(), FindByDevicePath(path));
   if (it != devices_.end()) {
     VLOG(2) << "Got request to add existing device: " << path.value();
     return false;
   }
 
   scoped_refptr<DrmDevice> device = drm_device_generator_->CreateDevice(
       path, std::move(file), !primary_device_);
   if (!device) {
-    LOG(WARNING) << "Could not initialize DRM device for " << path.value();
+    // This is expected for non-modesetting devices like VGEM.
+    VLOG(1) << "Could not initialize DRM device for " << path.value();
     return false;
   }
 
   if (!primary_device_)
     primary_device_ = device;
 
   devices_.push_back(device);
   return true;
 }
 
@@ skipping 39 matching lines @@
 
 scoped_refptr<DrmDevice> DrmDeviceManager::GetPrimaryDrmDevice() {
   return primary_device_;
 }
 
 const DrmDeviceVector& DrmDeviceManager::GetDrmDevices() const {
   return devices_;
 }
 
 }  // namespace ui