Account for device scale factor in AppWindow.setShape(), under Windows.

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

Index: ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index 877e8d1ccb3e30491c326022d939acfcb466e75c..2fc4cd976afd533180b25dd44cffd48bd8535870 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -280,7 +280,30 @@ gfx::Rect DesktopWindowTreeHostWin::GetWorkAreaBoundsInScreen() const {
 
 void DesktopWindowTreeHostWin::SetShape(gfx::NativeRegion native_region) {
   if (native_region) {
-    message_handler_->SetRegion(gfx::CreateHRGNFromSkRegion(*native_region));
+

[sky, 2014/09/04 13:23:05]

nit: no newline here.

[Wez, 2014/09/04 17:50:50]

Done.

+    // TODO(wez): This would be a lot simpler if we were passed an SkPath.
+    // See crbug.com/410593.
+    gfx::NativeRegion shape = native_region;
+    SkRegion device_region;
+    if (gfx::IsInHighDPIMode()) {
+      shape = &device_region;
+      const float& scale = gfx::win::GetDeviceScaleFactor();

[sky, 2014/09/04 13:23:05]

I think you want GetDPIScale() and no &, just const float scale. If you don't
think you want GetDPI, how come you want the scale factor?

[sky, 2014/09/04 17:40:09]

Actually, both are the same, so it shouldn't matter.

[Wez, 2014/09/04 17:50:50]

Re GetDPIScale: Done.

Re const float&: We want to use const& when complex types are returned, IIUC, to
help the compiler optimize out a potential copy, so it seems preferable to use
it consistently for both complex and POD types - that OK?

+      std::vector<SkIRect> rects;
+      for (SkRegion::Iterator it(*native_region); !it.done(); it.next()) {
+        const SkIRect& rect = it.rect();
+        SkRect scaled_rect =
+            SkRect::MakeLTRB(rect.left() * scale, rect.top() * scale,
+                             rect.right() * scale, rect.bottom() * scale);
+        SkIRect rounded_scaled_rect;
+        scaled_rect.roundOut(&rounded_scaled_rect);
+        rects.push_back(rounded_scaled_rect);
+      }
+      if (!rects.empty()) {

[sky, 2014/09/04 13:23:05]

nit: no {}

[Wez, 2014/09/04 17:50:50]

Done.

+        device_region.setRects(&rects[0], rects.size());
+      }
+    }
+
+    message_handler_->SetRegion(gfx::CreateHRGNFromSkRegion(*shape));
   } else {
     message_handler_->SetRegion(NULL);
   }