Fix the uses of T* conversion operator from scoped_refptr<T> which is now removed.

ui/ozone/platform/dri/screen_manager.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/screen_manager.h"
 
 #include <xf86drmMode.h>
 
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/rect.h"
@@ skipping 157 matching lines @@
 
 bool ScreenManager::ModesetDisplayController(
     HardwareDisplayController* controller,
     const gfx::Point& origin,
     const drmModeModeInfo& mode) {
   controller->set_origin(origin);
   // Create a surface suitable for the current controller.
   scoped_refptr<ScanoutBuffer> buffer =
       buffer_generator_->Create(gfx::Size(mode.hdisplay, mode.vdisplay));
 
-  if (!buffer) {
+  if (!buffer.get()) {
     LOG(ERROR) << "Failed to create scanout buffer";
     return false;
   }
 
   if (!controller->Modeset(OverlayPlane(buffer), mode)) {
     LOG(ERROR) << "Failed to modeset controller";
     return false;
   }
 
   return true;
@@ skipping 14 matching lines @@
 
   // When things go wrong revert back to the previous configuration since
   // it is expected that the configuration would not have changed if
   // things fail.
   (*original)->AddCrtc((*mirror)->RemoveCrtc(crtc));
   (*original)->Enable();
   return false;
 }
 
 }  // namespace ui