gfx: Use unsigned strides for gpu memory buffers.

ui/ozone/platform/drm/gpu/gbm_buffer.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/drm/gpu/gbm_buffer.h"
 
 #include <drm.h>
 #include <fcntl.h>
 #include <gbm.h>
 #include <xf86drm.h>
@@ skipping 134 matching lines @@
 // static
 scoped_refptr<GbmBuffer> GbmBuffer::CreateBufferFromFds(
     const scoped_refptr<GbmDevice>& gbm,
     gfx::BufferFormat format,
     const gfx::Size& size,
     std::vector<base::ScopedFD>&& fds,
     const std::vector<gfx::NativePixmapPlane>& planes) {
   TRACE_EVENT2("drm", "GbmBuffer::CreateBufferFromFD", "device",
                gbm->device_path().value(), "size", size.ToString());
   DCHECK_LE(fds.size(), planes.size());
-  DCHECK_EQ(planes[0].offset, 0);
+  DCHECK_EQ(planes[0].offset, 0u);
 
   uint32_t fourcc_format = GetFourCCFormatFromBufferFormat(format);
 
   // Use scanout if supported.
   bool use_scanout = gbm_device_is_format_supported(
       gbm->device(), fourcc_format, GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
 
   gbm_bo* bo = nullptr;
   if (use_scanout) {
     struct gbm_import_fd_data fd_data;
@@ skipping 136 matching lines @@
   DCHECK(!processing_callback_.is_null());
   if (!processing_callback_.Run(this, processed_pixmap_)) {
     LOG(ERROR) << "Failed processing NativePixmap";
     return nullptr;
   }
 
   return processed_pixmap_->buffer();
 }
 
 }  // namespace ui