Extract touchscreen device management into a generic manager

ui/ozone/ozone_platform.cc

Index: ui/ozone/ozone_platform.cc
diff --git a/ui/ozone/ozone_platform.cc b/ui/ozone/ozone_platform.cc
index 358556497938d2e4f7b04106c446b755b8d5cae8..ab21af9992c2efd1e2cd8afa2e427de99db157cc 100644
--- a/ui/ozone/ozone_platform.cc
+++ b/ui/ozone/ozone_platform.cc
@@ -5,6 +5,7 @@
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
+#include "ui/events/device_data_manager.h"
 #include "ui/ozone/ozone_platform.h"
 #include "ui/ozone/ozone_switches.h"
 #include "ui/ozone/platform_object.h"
@@ -38,6 +39,9 @@ void OzonePlatform::InitializeForUI() {
     return;
   g_platform_initialized_ui = true;
   instance_->InitializeUI();
+  // This is deliberately created after initializing so that the platform can
+  // create its own version of DDM.
+  DeviceDataManager::CreateInstance();
 }
 
 // static