Refactor Udev device support in Ozone and add a DRM hotplug monitor

ui/events/ozone/evdev/event_factory_evdev.cc

Index: ui/events/ozone/evdev/event_factory_evdev.cc
diff --git a/ui/events/ozone/evdev/event_factory_evdev.cc b/ui/events/ozone/evdev/event_factory_evdev.cc
index a36d9e7118708cad33828dbb680adeababbc7a04..0ab15228042e1ff8637d6c72715ee343f3f10b45 100644
--- a/ui/events/ozone/evdev/event_factory_evdev.cc
+++ b/ui/events/ozone/evdev/event_factory_evdev.cc
@@ -16,10 +16,6 @@
 #include "ui/events/ozone/evdev/key_event_converter_evdev.h"
 #include "ui/events/ozone/evdev/touch_event_converter_evdev.h"
 
-#if defined(USE_UDEV)
-#include "ui/events/ozone/evdev/device_manager_udev.h"
-#endif
-
 #if defined(USE_EVDEV_GESTURES)
 #include "ui/events/ozone/evdev/libgestures_glue/event_reader_libevdev_cros.h"
 #include "ui/events/ozone/evdev/libgestures_glue/gesture_interpreter_libevdev_cros.h"
@@ -141,8 +137,11 @@ EventFactoryEvdev::EventFactoryEvdev()
                      base::Unretained(this))),
       weak_ptr_factory_(this) {}
 
-EventFactoryEvdev::EventFactoryEvdev(CursorDelegateEvdev* cursor)
-    : ui_task_runner_(base::MessageLoopProxy::current()),
+EventFactoryEvdev::EventFactoryEvdev(
+    CursorDelegateEvdev* cursor,
+    scoped_ptr<DeviceManagerEvdev> device_manager)
+    : device_manager_(device_manager.Pass()),
+      ui_task_runner_(base::MessageLoopProxy::current()),
       file_task_runner_(base::MessageLoopProxy::current()),
       cursor_(cursor),
       dispatch_callback_(
@@ -217,18 +216,13 @@ void EventFactoryEvdev::OnDeviceRemoved(const base::FilePath& path) {
 void EventFactoryEvdev::StartProcessingEvents() {
   CHECK(ui_task_runner_->RunsTasksOnCurrentThread());
 
-#if defined(USE_UDEV)
-  // Scan for input devices using udev.
-  device_manager_ = CreateDeviceManagerUdev();
-#else
-  // No udev support. Scan devices manually in /dev/input.
-  device_manager_ = CreateDeviceManagerManual();
-#endif
-
-  // Scan & monitor devices.
-  device_manager_->ScanAndStartMonitoring(
-      base::Bind(&EventFactoryEvdev::OnDeviceAdded, base::Unretained(this)),
-      base::Bind(&EventFactoryEvdev::OnDeviceRemoved, base::Unretained(this)));
+  if (device_manager_) {
+    // Scan & monitor devices.
+    device_manager_->ScanAndStartMonitoring(
+        base::Bind(&EventFactoryEvdev::OnDeviceAdded, base::Unretained(this)),
+        base::Bind(&EventFactoryEvdev::OnDeviceRemoved,
+                   base::Unretained(this)));
+  }
 }
 
 void EventFactoryEvdev::SetFileTaskRunner(