WIP: have aura-mus convert to dips before sending out events

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index b71391bc5bab8f5977235c55f7e570fe3f791b1c..27200233613e7a7091088f10cfba238a263947e8 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -44,6 +44,7 @@
 #include "ui/aura/window_delegate.h"
 #include "ui/aura/window_tracker.h"
 #include "ui/base/ui_base_types.h"
+#include "ui/compositor/compositor.h"
 #include "ui/display/display.h"
 #include "ui/display/screen.h"
 #include "ui/events/event.h"
@@ -1132,6 +1133,25 @@ void WindowTreeClient::OnWindowInputEvent(uint32_t event_id,
     return;
   }
 
+  // Mus sends screen coordinates, need to convert to DIPs.
+  if (event->IsLocatedEvent() && !roots_.empty()) {
+    // TODO: this isn't right, we need to find the matching host and use it's
+    // scale.
+    const float scale_factor = (*roots_.begin())
+                                   ->GetWindow()
+                                   ->GetHost()
+                                   ->compositor()
+                                   ->device_scale_factor();
+    if (scale_factor != 1) {
+      gfx::Point host_location = gfx::ConvertPointToDIP(
+          scale_factor, event->AsLocatedEvent()->location());
+      event->AsLocatedEvent()->set_location(host_location);
+      gfx::Point root_location = gfx::ConvertPointToDIP(
+          scale_factor, event->AsLocatedEvent()->root_location());
+      event->AsLocatedEvent()->set_root_location(root_location);
+    }
+  }
+
   if (matches_pointer_watcher && has_pointer_watcher_) {
     DCHECK(event->IsPointerEvent());
     delegate_->OnPointerEventObserved(*event->AsPointerEvent(),