Move cursor when it's hidden so that UX can update correctly

ui/aura/env.cc

Index: ui/aura/env.cc
diff --git a/ui/aura/env.cc b/ui/aura/env.cc
index b00dd89a6b84095150c75649b599ca292c4dd9e0..90f3fbff4e20e2bfc4508d813d81ef9d32e25947 100644
--- a/ui/aura/env.cc
+++ b/ui/aura/env.cc
@@ -28,6 +28,7 @@ Env* Env::instance_ = NULL;
 
 Env::Env()
     : mouse_button_flags_(0),
+      is_cursor_hidden_(false),
       is_touch_down_(false),
       render_white_bg_(true),
       stacking_client_(NULL) {
@@ -69,6 +70,19 @@ void Env::SetLastMouseLocation(const Window& window,
     client->ConvertPointToScreen(&window, &last_mouse_location_);
 }
 
+void Env::SetCursorShown(bool cursor_shown) {
+  if (cursor_shown) {
+    // Protect against restoring a position that hadn't been saved.
+    if (is_cursor_hidden_)
+      last_mouse_location_ = hidden_cursor_location_;
+    is_cursor_hidden_ = false;
+  } else {
+    hidden_cursor_location_ = last_mouse_location_;
+    last_mouse_location_ = gfx::Point(-10000, -10000);

[sky, 2012/08/14 16:01:00]

Won't this cause all sorts of weirdness if the hide occurs during a mouse drag
or something?

+    is_cursor_hidden_ = true;
+  }
+}
+
 void Env::SetDisplayManager(DisplayManager* display_manager) {
   display_manager_.reset(display_manager);
 #if defined(USE_X11)