Minimize headless code that refers to aura.

headless/lib/browser/headless_browser_main_parts.cc

 // Copyright 2015 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 "headless/lib/browser/headless_browser_main_parts.h"
 
 #include "headless/lib/browser/headless_browser_context_impl.h"
 #include "headless/lib/browser/headless_browser_impl.h"
 #include "headless/lib/browser/headless_devtools.h"
 #include "headless/lib/browser/headless_screen.h"
-#include "ui/aura/env.h"
-#include "ui/display/screen.h"
 
 namespace headless {
 
-namespace {
-
-void PlatformInitialize(const gfx::Size& screen_size) {
-  HeadlessScreen* screen = HeadlessScreen::Create(screen_size);
-  display::Screen::SetScreenInstance(screen);
-}
-
-void PlatformExit() {
-}
-
-}  // namespace
-
 HeadlessBrowserMainParts::HeadlessBrowserMainParts(HeadlessBrowserImpl* browser)
     : browser_(browser)
     , devtools_http_handler_started_(false) {}
 
 HeadlessBrowserMainParts::~HeadlessBrowserMainParts() {}
 
 void HeadlessBrowserMainParts::PreMainMessageLoopRun() {
   if (browser_->options()->devtools_endpoint.address().IsValid()) {
     StartLocalDevToolsHttpHandler(browser_->options());
     devtools_http_handler_started_ = true;
   }
-  PlatformInitialize(browser_->options()->window_size);
+  browser_->PlatformInitialize();
 }
 
 void HeadlessBrowserMainParts::PostMainMessageLoopRun() {
   if (devtools_http_handler_started_) {
     StopLocalDevToolsHttpHandler();
     devtools_http_handler_started_ = false;
   }
-  PlatformExit();
 }
 
 }  // namespace headless