[8/8][Ozone-Dri] Pass DRM FD to GPU process on hotplug event

ui/ozone/common/gpu/ozone_gpu_messages.h

 // 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.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <vector>
 
+#include "base/file_descriptor_posix.h"
 #include "ipc/ipc_message_macros.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/ipc/gfx_param_traits.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/ozone/common/gpu/ozone_gpu_message_params.h"
 #include "ui/ozone/ozone_export.h"
 
 #undef IPC_MESSAGE_EXPORT
@@ skipping 64 matching lines @@
 
 // Configure a display with the specified mode at the specified location.
 IPC_MESSAGE_CONTROL3(OzoneGpuMsg_ConfigureNativeDisplay,
                      int64_t,  // display ID
                      ui::DisplayMode_Params,  // display mode
                      gfx::Point)  // origin for the display
 
 IPC_MESSAGE_CONTROL1(OzoneGpuMsg_DisableNativeDisplay,
                      int64_t)  // display ID
 
-IPC_MESSAGE_CONTROL1(OzoneGpuMsg_AddGraphicsDevice,
-                     base::FilePath /* device_path */)
+IPC_MESSAGE_CONTROL2(OzoneGpuMsg_AddGraphicsDevice,
+                     base::FilePath /* device_path */,

[jln (very slow on Chromium), 2015/02/19 01:28:58]

What is the reason for still sending the device path and not on the device_fd?

[dnicoara, 2015/02/19 02:42:52]

To uniquely identify the device. These events are a result of hotplug events and
the event provides a file path (no FD).

+                     base::FileDescriptor /* device_fd */)
 
 IPC_MESSAGE_CONTROL1(OzoneGpuMsg_RemoveGraphicsDevice,
                      base::FilePath /* device_path */)
 
 // Take control of the display
 IPC_MESSAGE_CONTROL0(OzoneGpuMsg_TakeDisplayControl)
 
 // Let other entity control the display
 IPC_MESSAGE_CONTROL0(OzoneGpuMsg_RelinquishDisplayControl)
 
 //------------------------------------------------------------------------------
 // Browser Messages
 // These messages are from the GPU to the browser process.
 
 // Updates the list of active displays.
 IPC_MESSAGE_CONTROL1(OzoneHostMsg_UpdateNativeDisplays,
                      std::vector<ui::DisplaySnapshot_Params>)
 
 IPC_MESSAGE_CONTROL2(OzoneHostMsg_DisplayConfigured,
                      int64_t /* display_id */,
                      bool /* status */)