aura-x11: Fix touch-calibration for multi-monitor setups.

ui/base/events/event.cc

Index: ui/base/events/event.cc
diff --git a/ui/base/events/event.cc b/ui/base/events/event.cc
index fdc40b42df159137ddc75e34bc5a985e19302fad..f2881072be311dda12aad0d1fc49217967ca8486 100644
--- a/ui/base/events/event.cc
+++ b/ui/base/events/event.cc
@@ -8,6 +8,7 @@
 #include <X11/Xlib.h>
 #endif
 
+#include <cmath>
 #include <cstring>
 
 #include "ui/base/keycodes/keyboard_code_conversion.h"
@@ -37,6 +38,17 @@ base::NativeEvent CopyNativeEvent(const base::NativeEvent& event) {
 #endif
 }
 
+gfx::Point CalibratePoint(const gfx::Point& point,
+                          const gfx::Size& from,
+                          const gfx::Size& to) {
+  float calibrated_x =
+      static_cast<float>(point.x()) * to.width() / from.width();
+  float calibrated_y =
+      static_cast<float>(point.y()) * to.height() / from.height();
+  return gfx::Point(static_cast<int>(floorf(calibrated_x + 0.5f)),
+                    static_cast<int>(floorf(calibrated_y + 0.5f)));
+}
+
 }  // namespace
 
 namespace ui {
@@ -291,6 +303,11 @@ TouchEvent::TouchEvent(EventType type,
 TouchEvent::~TouchEvent() {
 }
 
+void TouchEvent::CalibrateLocation(const gfx::Size& from, const gfx::Size& to) {
+  location_ = CalibratePoint(location_, from, to);
+  root_location_ = CalibratePoint(root_location_, from, to);
+}
+
 void TouchEvent::UpdateForRootTransform(const Transform& root_transform) {
   LocatedEvent::UpdateForRootTransform(root_transform);
   gfx::Point3f scale;