Enable hidpi on Linux, refactor a bit on Windows to share

ui/compositor/test/test_suite.cc

 // 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/compositor/test/test_suite.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "ui/compositor/compositor.h"
 #include "ui/compositor/compositor_switches.h"
+#include "ui/gfx/dpi.h"
 #include "ui/gfx/gfx_paths.h"
 #include "ui/gl/gl_surface.h"
 
-#if defined(OS_WIN)
-#include "ui/gfx/win/dpi.h"
-#endif
 
 namespace ui {
 namespace test {
 
 CompositorTestSuite::CompositorTestSuite(int argc, char** argv)
     : TestSuite(argc, argv) {}
 
 CompositorTestSuite::~CompositorTestSuite() {}
 
 void CompositorTestSuite::Initialize() {
   base::TestSuite::Initialize();
   gfx::GLSurface::InitializeOneOffForTests();
 
   gfx::RegisterPathProvider();
 
-#if defined(OS_WIN)
+#if defined(OS_WIN) || (defined(OS_LINUX) && !defined(OS_CHROMEOS))
   gfx::InitDeviceScaleFactor(1.0f);
 #endif
 
   message_loop_.reset(new base::MessageLoopForUI);
 }
 
 void CompositorTestSuite::Shutdown() {
   message_loop_.reset();
 
   base::TestSuite::Shutdown();
 }
 
 }  // namespace test
 }  // namespace ui