Short term workaround to deal with calculation error caused by inverted matrix.

ui/aura/root_window.cc

Index: ui/aura/root_window.cc
diff --git a/ui/aura/root_window.cc b/ui/aura/root_window.cc
index 7c95443b8a92cad7ce7b2ec2bb60d9b145fb4be2..89db56dd9e55cc6b91b063f79925662cccf829e2 100644
--- a/ui/aura/root_window.cc
+++ b/ui/aura/root_window.cc
@@ -671,6 +671,24 @@ void RootWindow::ClearMouseHandlers() {
 
 void RootWindow::TransformEventForDeviceScaleFactor(ui::LocatedEvent* event) {
   event->UpdateForRootTransform(GetRootTransform());
+#if defined(OS_CHROMEOS)

[oshima, 2013/03/20 20:52:53]

I put inside ifdef to avoid potential issues on windows,
and this is short term workaround.

+  const gfx::Rect& root_bounds = bounds();
+  if (host_->GetBounds().Contains(event->system_location()) &&
+      !root_bounds.Contains(event->root_location())) {
+    // Make sure that the mouse location inside the host window gets
+    // translated inside root window.
+    // TODO(oshima): This is (hopefully) short term bandaid to deal
+    // with calculation error in inverted matrix. We'll try better
+    // alternative (crbug.com/222483) for m28.
+    int x = event->location().x();
+    int y = event->location().y();
+    x = std::min(std::max(x, root_bounds.x()), root_bounds.right());
+    y = std::min(std::max(y, root_bounds.y()), root_bounds.bottom());
+    const gfx::Point new_location(x, y);
+    event->set_location(new_location);
+    event->set_root_location(new_location);
+  }
+#endif  // defined(OS_CHROMEOS)
 }
 
 void RootWindow::HandleMouseMoved(const ui::MouseEvent& event, Window* target) {