[Ozone-Dri] Gracefully handle DRM devices with no resources

ui/ozone/platform/dri/native_display_delegate_dri.cc

 // Copyright 2014 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/dri/native_display_delegate_dri.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_descriptor_posix.h"
 #include "base/files/file.h"
@@ skipping 208 matching lines @@
   auto it =
       std::find_if(devices_.begin(), devices_.end(), FindByDevicePath(path));
   if (it != devices_.end()) {
     LOG(WARNING) << "Got request to add existing device '" << path.value()
                  << "'";
     return;
   }
 
   scoped_refptr<DriWrapper> device =
       drm_device_generator_->CreateDevice(path, file.Pass());
+  if (!device) {
+    LOG(WARNING) << "Could not initialize DRM device for '" << path.value()

[alexst (slow to review), 2015/02/23 21:46:32]

Would this log every time there is a vgem device?

[dnicoara, 2015/02/23 21:49:10]

Yes.

+                 << "'";
+    return;
+  }
+
   devices_.push_back(device);
   if (io_task_runner_)
     device->InitializeTaskRunner(io_task_runner_);
 }
 
 void NativeDisplayDelegateDri::RemoveGraphicsDevice(
     const base::FilePath& path) {
   auto it =
       std::find_if(devices_.begin(), devices_.end(), FindByDevicePath(path));
   if (it == devices_.end()) {
@@ skipping 169 matching lines @@
 
     if (it == old_displays.end()) {
       screen_manager_->AddDisplayController(new_displays[i]->drm(),
                                             new_displays[i]->crtc(),
                                             new_displays[i]->connector());
     }
   }
 }
 
 }  // namespace ui