mac: Basic HighDPI implementation for web contents.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index e470c5c880dbdb7b4293e947082aeedc01fbd681..e776b41aa4aa06d8aa6f2caebf84e71e097c57c3 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -550,12 +550,6 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
     prefs.accelerated_compositing_enabled = false;
     prefs.accelerated_2d_canvas_enabled = false;
   }
-#if defined(OS_MACOSX)
-  // Mac doesn't have gfx::Screen::GetMonitorNearestWindow impl.
-  // crbug.com/125690.
-  prefs.default_device_scale_factor =
-      gfx::Monitor::GetDefaultDeviceScaleFactor();
-#else
   if (rvh->GetView()) {
     gfx::Monitor monitor = gfx::Screen::GetMonitorNearestWindow(
         rvh->GetView()->GetNativeView());
@@ -565,7 +559,6 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
     prefs.default_device_scale_factor =
         gfx::Monitor::GetDefaultDeviceScaleFactor();;
   }
-#endif
 
   if (command_line.HasSwitch(switches::kDefaultTileWidth))
     prefs.default_tile_width =