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

content/browser/web_contents/web_contents_impl.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 "content/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 462 matching lines @@
       command_line.HasSwitch(switches::kEnableAcceleratedScrollableFrames);
   prefs.composited_scrolling_for_frames_enabled =
       command_line.HasSwitch(switches::kEnableCompositedScrollingForFrames);
   prefs.show_paint_rects =
       command_line.HasSwitch(switches::kShowPaintRects);
   prefs.render_vsync_enabled =
       !command_line.HasSwitch(switches::kDisableGpuVsync);
   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 =
       command_line.HasSwitch(switches::kForceCompositingMode) &&
       !command_line.HasSwitch(switches::kDisableForceCompositingMode);
+#endif
   prefs.fixed_position_compositing_enabled =
       command_line.HasSwitch(switches::kEnableCompositingForFixedPosition);
   prefs.accelerated_2d_canvas_enabled =
       GpuProcessHost::gpu_enabled() &&
       !command_line.HasSwitch(switches::kDisableAccelerated2dCanvas);
   prefs.deferred_2d_canvas_enabled =
       !command_line.HasSwitch(switches::kDisableDeferred2dCanvas);
   prefs.antialiased_2d_canvas_disabled =
       command_line.HasSwitch(switches::kDisable2dCanvasAntialiasing);
   prefs.accelerated_painting_enabled =
@@ skipping 102 matching lines @@
   }
 
   if (ChildProcessSecurityPolicyImpl::GetInstance()->HasWebUIBindings(
           rvh->GetProcess()->GetID())) {
     prefs.loads_images_automatically = true;
     prefs.javascript_enabled = true;
   }
 
   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:, about: and
   // chrome-devtools: pages (unless it's specifically allowed).
   if ((url.SchemeIs(chrome::kChromeDevToolsScheme) ||
       url.SchemeIs(chrome::kChromeUIScheme) ||
       (url.SchemeIs(chrome::kAboutScheme) &&
        url.spec() != chrome::kAboutBlankURL)) &&
       !command_line.HasSwitch(switches::kAllowWebUICompositing)) {
     prefs.accelerated_compositing_enabled = false;
     prefs.accelerated_2d_canvas_enabled = false;
   }
-
+#endif
   if (command_line.HasSwitch(switches::kDefaultTileWidth))
     prefs.default_tile_width =
         GetSwitchValueAsInt(command_line, switches::kDefaultTileWidth, 1);
   if (command_line.HasSwitch(switches::kDefaultTileHeight))
     prefs.default_tile_height =
         GetSwitchValueAsInt(command_line, switches::kDefaultTileHeight, 1);
   if (command_line.HasSwitch(switches::kMaxUntiledLayerWidth))
     prefs.max_untiled_layer_width =
         GetSwitchValueAsInt(command_line, switches::kMaxUntiledLayerWidth, 1);
   if (command_line.HasSwitch(switches::kMaxUntiledLayerHeight))
@@ skipping 2772 matching lines @@
 
 BrowserPluginGuest* WebContentsImpl::GetBrowserPluginGuest() {
   return browser_plugin_guest_.get();
 }
 
 BrowserPluginEmbedder* WebContentsImpl::GetBrowserPluginEmbedder() {
   return browser_plugin_embedder_.get();
 }
 
 }  // namespace content