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

ui/aura/root_window.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 "ui/aura/root_window.h"
 
 #include <vector>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 653 matching lines @@
   mouse_pressed_handler_ = NULL;
   mouse_moved_handler_ = NULL;
   mouse_event_dispatch_target_ = NULL;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RootWindow, private:
 
 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) {
   if (target == mouse_moved_handler_)
     return;
 
   DispatchMouseEnterOrExit(event, ui::ET_MOUSE_EXITED);
 
   if (mouse_event_dispatch_target_ != target) {
     mouse_moved_handler_ = NULL;
@@ skipping 469 matching lines @@
 
 gfx::Transform RootWindow::GetRootTransform() const {
   float scale = ui::GetDeviceScaleFactor(layer());
   gfx::Transform transform;
   transform.Scale(scale, scale);
   transform *= layer()->transform();
   return transform;
 }
 
 }  // namespace aura