Implement DRM Native Pixmap using prime buffer

ui/ozone/platform/drm/host/drm_display_host_manager.cc

Index: ui/ozone/platform/drm/host/drm_display_host_manager.cc
diff --git a/ui/ozone/platform/drm/host/drm_display_host_manager.cc b/ui/ozone/platform/drm/host/drm_display_host_manager.cc
index 85b94e93fc93d92657000dd84ea872fe41a5191c..458c247ed2b509fe5cb6a0faed3833627e9596b8 100644
--- a/ui/ozone/platform/drm/host/drm_display_host_manager.cc
+++ b/ui/ozone/platform/drm/host/drm_display_host_manager.cc
@@ -9,7 +9,6 @@
 #include <xf86drm.h>
 #include <utility>
 
-#include "base/files/file_enumerator.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/strings/stringprintf.h"
@@ -36,8 +35,6 @@ typedef base::Callback<void(const base::FilePath&,
     OnOpenDeviceReplyCallback;
 
 const char kDefaultGraphicsCardPattern[] = "/dev/dri/card%d";
-const char kVgemDevDriCardPath[] = "/dev/dri/";
-const char kVgemSysCardPath[] = "/sys/bus/platform/devices/vgem/drm/";
 
 const char* kDisplayActionString[] = {
     "ADD", "REMOVE", "CHANGE",
@@ -95,22 +92,6 @@ base::FilePath GetPrimaryDisplayCardPath() {
   return base::FilePath();  // Not reached.
 }
 
-base::FilePath GetVgemCardPath() {
-  base::FileEnumerator file_iter(base::FilePath(kVgemSysCardPath), false,
-                                 base::FileEnumerator::DIRECTORIES,
-                                 FILE_PATH_LITERAL("card*"));
-
-  while (!file_iter.Next().empty()) {
-    // Inspect the card%d directories in the directory and extract the filename.
-    std::string vgem_card_path =
-        kVgemDevDriCardPath + file_iter.GetInfo().GetName().BaseName().value();
-    DVLOG(1) << "VGEM card path is " << vgem_card_path;
-    return base::FilePath(vgem_card_path);
-  }
-  DVLOG(1) << "Don't support VGEM";
-  return base::FilePath();
-}
-
 class FindDrmDisplayHostById {
  public:
   explicit FindDrmDisplayHostById(int64_t display_id)
@@ -152,8 +133,6 @@ DrmDisplayHostManager::DrmDisplayHostManager(
     }
     drm_devices_[primary_graphics_card_path_] =
         primary_graphics_card_path_sysfs;
-
-    vgem_card_path_ = GetVgemCardPath();
   }
 
   device_manager_->AddObserver(this);
@@ -264,8 +243,6 @@ void DrmDisplayHostManager::ProcessEvent() {
             << " for " << event.path.value();
     switch (event.action_type) {
       case DeviceEvent::ADD:
-        if (event.path == vgem_card_path_)
-          continue;
         if (drm_devices_.find(event.path) == drm_devices_.end()) {
           task_pending_ = base::WorkerPool::PostTask(
               FROM_HERE,
@@ -285,7 +262,6 @@ void DrmDisplayHostManager::ProcessEvent() {
       case DeviceEvent::REMOVE:
         DCHECK(event.path != primary_graphics_card_path_)
             << "Removing primary graphics card";
-        DCHECK(event.path != vgem_card_path_) << "Removing VGEM device";
         auto it = drm_devices_.find(event.path);
         if (it != drm_devices_.end()) {
           task_pending_ = base::ThreadTaskRunnerHandle::Get()->PostTask(