Fix high-DPI on Windows to make use of DIP scaling in WebKit.

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 8b1f8e985466a3194a7968a1ae47141fa6bdb2d3..28c4d748175edbe8ca5d928d93d24d9d47af408c 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -497,9 +497,13 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
   prefs.accelerated_compositing_enabled =
       GpuProcessHost::gpu_enabled() &&
       !command_line.HasSwitch(switches::kDisableAcceleratedCompositing);
+#if defined(OS_WIN) && defined(ENABLE_HIDPI)
+  prefs.force_compositing_mode = true;
+#else
   prefs.force_compositing_mode =
       content::IsForceCompositingModeEnabled() &&
       !command_line.HasSwitch(switches::kDisableForceCompositingMode);
+#endif
   prefs.fixed_position_compositing_enabled =
       command_line.HasSwitch(switches::kEnableCompositingForFixedPosition);
   prefs.accelerated_2d_canvas_enabled =
@@ -621,6 +625,10 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
 
   prefs.is_online = !net::NetworkChangeNotifier::IsOffline();
 
+#if defined(OS_WIN) && defined(ENABLE_HIDPI)
+  prefs.accelerated_compositing_enabled = true;
+  prefs.accelerated_2d_canvas_enabled = true;
+#else
   // Force accelerated compositing and 2d canvas off for chrome: and about:
   // pages (unless it's specifically allowed).
   if ((url.SchemeIs(chrome::kChromeUIScheme) ||
@@ -630,6 +638,7 @@ WebPreferences WebContentsImpl::GetWebkitPrefs(RenderViewHost* rvh,
     prefs.accelerated_compositing_enabled = false;
     prefs.accelerated_2d_canvas_enabled = false;
   }
+#endif
 
   if (url.SchemeIs(chrome::kChromeDevToolsScheme))
     prefs.show_fps_counter = false;