Remove IsDIPEnabled from Screen

ui/gfx/screen_ios.mm

 // Copyright (c) 2012 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 "ui/gfx/screen.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "ui/gfx/display.h"
 
 namespace {
 
 class ScreenIos : public gfx::Screen {
-  virtual bool IsDIPEnabled() override {
-    return true;
-  }
-
   virtual gfx::Point GetCursorScreenPoint() override {
     NOTIMPLEMENTED();
     return gfx::Point(0, 0);
   }
 
   virtual gfx::NativeWindow GetWindowUnderCursor() override {
     NOTIMPLEMENTED();
     return gfx::NativeWindow();
   }
 
@@ skipping 58 matching lines @@
 
 }  // namespace
 
 namespace gfx {
 
 Screen* CreateNativeScreen() {
   return new ScreenIos;
 }
 
 }  // namespace gfx